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ASPM on rpi 400

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User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

ASPM on rpi 400

Sun Apr 06, 2025 3:43 pm

I learned that in 2019 the VIA VL805 PCIe USB 3.0 controller firmware was updated to support ASPM on the Raspberry Pi 4B / 400. I was surprised when running lspci -vvv under Raspberry Pi OS to see ASPM enabled on the USB controller but disbled on that the Root Complex.

From my (admittedly limited) understanding, ASPM power savings require both ends of the PCIe link to have compatible ASPM settings enabled, otherwise the link remains in L0.

I’m curious how ASPM power savings could still be in effect in this configuration – is there something I’m missing, or is there platform-specific behaviour at play here?

My lspci dump is here: https://github.com/spectrum4/notes/blob ... ecoded.txt

Lines 25/26 for the Root Complex show:

Code: Select all

		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-

whereas lines 89/90 for USB controller show:

Code: Select all

		LnkCtl:	ASPM L0s L1 Enabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-

Note, other publicly posted lspci dumps I have found online seem to match mine, e.g. https://pastebin.com/SS71pBD6

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Sun Apr 06, 2025 4:27 pm

It does indeed require both ends to be enabled.

There was an upstream bug that incorrectly set overrides for L0s which broke L1 as well. Please report the output of uname -a.

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Sun Apr 06, 2025 5:36 pm

Thanks jdb for the quick reply on a Sunday evening! I wasn't expecting that, that really is very kind.

I'm actually running a custom 5.15 kernel of my own (https://github.com/petemoore/linux/comm ... -pcie-usb/) which is just a few commits on top of https://github.com/raspberrypi/linux/tree/rpi-5.15.y. The extra commits just provide additional MMIO tracing to help me understand the pcie initialisation process. Raspberry Pi OS version is https://downloads.raspberrypi.com/raspi ... 023-02-22/.

Thanks!

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Sun Apr 06, 2025 6:31 pm

Hm, a kernel that old doesn't have the bug I was thinking about. But, no guarantee that there isn't another, either. As you're using something that's basically EOL and custom, I'm not going to spend time chasing this.

I will confirm that recent packaged kernels don't have this issue, then it will be up to you to update the version you base your additions on.

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Sun Apr 06, 2025 9:49 pm

Many thanks jdb! Mostly out of curiosity, is this the fix you were thinking about?
https://github.com/raspberrypi/linux/co ... f59782c131

I'll see if I can adapt my patches for a newer kernel, or replace with this new kernel tracing: https://lore.kernel.org/lkml/466449a1-3 ... inc.com/t/

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Mon Apr 07, 2025 8:33 am

There's a bug in the LPAE BCM2711 defconfig (32-bit kernel with 36-bit addressing). CONFIG_PCIE_ASPM isn't set which means the kernel doesn't set the default policy. The VL805 turns on ASPM by itself, but this means you only get L0s at one end of the link.

Edit: this kernel is effectively deprecated - use bcm2711_defconfig from arch/arm64 instead.

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Tue Apr 08, 2025 5:40 pm

I've taken the latest Raspberry Pi OS 64 bit release, run `sudo apt-get update` and `sudo apt-get upgrade`, run `sudo rpi-eeprom-update` and rebooted to pick up all the changes. However, when I run `lspci` I am still getting ASPM as disabled on the root complex.

Code: Select all

pmoore@rpi400:~ $ sudo lspci -vvvvv
00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2711 PCIe Bridge (rev 20) (prog-if 00 [Normal decode])
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 27
	Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
	Memory behind bridge: 00000000-000fffff [size=1M] [32-bit]
	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled] [64-bit]
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR- NoISA- VGA- VGA16- MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [48] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
		Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=1 PME-
	Capabilities: [ac] Express (v2) Root Port (Slot-), MSI 00
		DevCap:	MaxPayload 512 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	CorrErr- NonFatalErr- FatalErr- UnsupReq-
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr+ NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
			ClockPM+ Surprise- LLActRep- BwNot+ ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk+ <-------------------- HERE
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt+ ABWMgmt+
		RootCap: CRSVisible+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp- 10BitTagReq- OBFF Via WAKE#, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd-
			 AtomicOpsCap: Routing- 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled, ARIFwd-
			 AtomicOpsCtl: ReqEn- EgressBlck-
		LnkCap2: Supported Link Speeds: 2.5-5GT/s, Crosslink- Retimer- 2Retimers- DRS+
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported, DRS-
			 DownstreamComp: Link Down - Not Determined
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
		RootCmd: CERptEn+ NFERptEn+ FERptEn+
		RootSta: CERcvd- MultCERcvd- UERcvd- MultUERcvd-
			 FirstFatal- NonFatalMsg- FatalMsg- IntMsg 0
		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
	Capabilities: [180 v1] Vendor Specific Information: ID=0000 Rev=0 Len=028 <?>
	Capabilities: [240 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			 PortCommonModeRestoreTime=8us PortTPowerOnTime=10us
		L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
			 T_CommonMode=1us LTR1.2_Threshold=0ns
		L1SubCtl2: T_PwrOn=10us
	Kernel driver in use: pcieport
01:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01) (prog-if 30 [XHCI])
	Subsystem: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0/usb@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 30
	Region 0: Memory at 600000000 (64-bit, non-prefetchable) [size=4K]
	Capabilities: [80] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot-,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [90] MSI: Enable+ Count=1/4 Maskable- 64bit+
		Address: 00000000fffffffc Data: 6540
	Capabilities: [c4] Express (v2) Endpoint, MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
			ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 0W
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr+ NonFatalErr- FatalErr- UnsupReq+ AuxPwr+ TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <2us, L1 <16us
			ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp-
		LnkCtl:	ASPM L0s L1 Enabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
		DevCap2: Completion Timeout: Range B, TimeoutDis+ NROPrPrP- LTR-
			 10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- TPHComp- ExtTPHComp-
			 AtomicOpsCap: 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled,
			 AtomicOpsCtl: ReqEn-
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis+
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
	Kernel driver in use: xhci_hcd

Here is my system version:

Code: Select all

pmoore@rpi400:~ $ uname -a
Linux rpi400 6.6.51+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.6.51-1+rpt3 (2024年10月08日) aarch64 GNU/Linux

Here is my bootloader version:

Code: Select all

pmoore@rpi400:~ $ sudo vcgencmd bootloader_version
2025年02月11日 17:00:13
version 75c1e570e99e14684e79e6ab8f5355d831440c71 (release)
timestamp 1739293213
update-time 1744133052
capabilities 0x0000007f

The VL805 firmware appears to be up-to-date:

Code: Select all

pmoore@rpi400:~ $ sudo rpi-eeprom-update
BOOTLOADER: up to date
 CURRENT: Tue 11 Feb 17:00:13 UTC 2025 (1739293213)
 LATEST: Tue 11 Feb 17:00:13 UTC 2025 (1739293213)
 RELEASE: default (/usr/lib/firmware/raspberrypi/bootloader-2711/default)
 Use raspi-config to change the release.
 VL805_FW: Using bootloader EEPROM
 VL805: up to date
 CURRENT: 000138c0
 LATEST: 000138c0
pmoore@rpi400:~ $

jdb, any ideas what might be wrong?

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Tue Apr 08, 2025 6:50 pm

Run sudo modprobe configs then do zgrep PCI /proc/config.gz. What lines are displayed?

Edit: you're still on 6.6.51 - you need to run sudo apt full-upgrade and reboot first.

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Tue Apr 08, 2025 7:45 pm

Many thanks jdb.

Unfortunately, this didn't resolve it for me... Is there anything else I can try?

Code: Select all

pmoore@rpi400:~ $ uname -a
Linux rpi400 6.12.20+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.20-1+rpt1~bpo12+1 (2025年03月19日) aarch64 GNU/Linux

Code: Select all

pmoore@rpi400:~ $ sudo lspci -vvvvv
00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2711 PCIe Bridge (rev 20) (prog-if 00 [Normal decode])
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 27
	Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
	Memory behind bridge: 00000000-000fffff [size=1M] [32-bit]
	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled] [64-bit]
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR- NoISA- VGA- VGA16- MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [48] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
		Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=1 PME-
	Capabilities: [ac] Express (v2) Root Port (Slot-), MSI 00
		DevCap:	MaxPayload 512 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	CorrErr- NonFatalErr- FatalErr- UnsupReq-
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr+ NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
			ClockPM+ Surprise- LLActRep- BwNot+ ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk+ <----------------- still disabled
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt+
		RootCap: CRSVisible+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp- 10BitTagReq- OBFF Via WAKE#, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd-
			 AtomicOpsCap: Routing- 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled, ARIFwd-
			 AtomicOpsCtl: ReqEn- EgressBlck-
		LnkCap2: Supported Link Speeds: 2.5-5GT/s, Crosslink- Retimer- 2Retimers- DRS+
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported, DRS-
			 DownstreamComp: Link Down - Not Determined
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
		RootCmd: CERptEn+ NFERptEn+ FERptEn+
		RootSta: CERcvd- MultCERcvd- UERcvd- MultUERcvd-
			 FirstFatal- NonFatalMsg- FatalMsg- IntMsg 0
		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
	Capabilities: [180 v1] Vendor Specific Information: ID=0000 Rev=0 Len=028 <?>
	Capabilities: [240 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			 PortCommonModeRestoreTime=8us PortTPowerOnTime=10us
		L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
			 T_CommonMode=1us LTR1.2_Threshold=0ns
		L1SubCtl2: T_PwrOn=10us
	Kernel driver in use: pcieport
01:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01) (prog-if 30 [XHCI])
	Subsystem: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0/usb@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 30
	Region 0: Memory at 600000000 (64-bit, non-prefetchable) [size=4K]
	Capabilities: [80] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot-,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [90] MSI: Enable+ Count=4/4 Maskable- 64bit+
		Address: 00000000fffffffc Data: 6540
	Capabilities: [c4] Express (v2) Endpoint, MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
			ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 0W
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr+ NonFatalErr- FatalErr- UnsupReq+ AuxPwr+ TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <2us, L1 <16us
			ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp-
		LnkCtl:	ASPM L0s L1 Enabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
		DevCap2: Completion Timeout: Range B, TimeoutDis+ NROPrPrP- LTR-
			 10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- TPHComp- ExtTPHComp-
			 AtomicOpsCap: 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled,
			 AtomicOpsCtl: ReqEn-
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis+
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
	Kernel driver in use: xhci_hcd

Code: Select all

pmoore@rpi400:~ $ sudo modprobe configs
pmoore@rpi400:~ $ zgrep PCI /proc/config.gz
CONFIG_BLK_MQ_PCI=y
# CONFIG_BT_INTEL_PCIE is not set
CONFIG_HAVE_PCI=y
CONFIG_GENERIC_PCI_IOMAP=y
CONFIG_PCI=y
CONFIG_PCI_DOMAINS=y
CONFIG_PCI_DOMAINS_GENERIC=y
CONFIG_PCI_SYSCALL=y
CONFIG_PCIEPORTBUS=y
CONFIG_PCIEAER=y
# CONFIG_PCIEAER_INJECT is not set
# CONFIG_PCIE_ECRC is not set
CONFIG_PCIEASPM=y
# CONFIG_PCIEASPM_DEFAULT is not set
CONFIG_PCIEASPM_POWERSAVE=y
# CONFIG_PCIEASPM_POWER_SUPERSAVE is not set
# CONFIG_PCIEASPM_PERFORMANCE is not set
CONFIG_PCIE_PME=y
CONFIG_PCIE_DPC=y
# CONFIG_PCIE_PTM is not set
CONFIG_PCI_MSI=y
CONFIG_PCI_QUIRKS=y
# CONFIG_PCI_DEBUG is not set
# CONFIG_PCI_STUB is not set
# CONFIG_PCI_IOV is not set
# CONFIG_PCI_NPEM is not set
# CONFIG_PCI_PRI is not set
# CONFIG_PCI_PASID is not set
CONFIG_PCI_LABEL=y
# CONFIG_PCI_DYNAMIC_OF_NODES is not set
# CONFIG_PCIE_BUS_TUNE_OFF is not set
CONFIG_PCIE_BUS_DEFAULT=y
# CONFIG_PCIE_BUS_SAFE is not set
# CONFIG_PCIE_BUS_PERFORMANCE is not set
# CONFIG_PCIE_BUS_PEER2PEER is not set
# CONFIG_HOTPLUG_PCI is not set
# PCI controller drivers
# CONFIG_PCIE_ALTERA is not set
CONFIG_PCIE_BRCMSTB=y
# CONFIG_PCI_HOST_THUNDER_PEM is not set
# CONFIG_PCI_HOST_THUNDER_ECAM is not set
# CONFIG_PCI_FTPCI100 is not set
# CONFIG_PCI_HOST_GENERIC is not set
# CONFIG_PCI_XGENE is not set
# CONFIG_PCIE_XILINX is not set
# Cadence-based PCIe controllers
# CONFIG_PCIE_CADENCE_PLAT_HOST is not set
# end of Cadence-based PCIe controllers
# DesignWare-based PCIe controllers
# CONFIG_PCIE_AL is not set
# CONFIG_PCI_MESON is not set
# CONFIG_PCI_HISI is not set
# CONFIG_PCIE_KIRIN is not set
# CONFIG_PCIE_DW_PLAT_HOST is not set
# end of DesignWare-based PCIe controllers
# Mobiveil-based PCIe controllers
# end of Mobiveil-based PCIe controllers
# PLDA-based PCIe controllers
# CONFIG_PCIE_MICROCHIP_HOST is not set
# end of PLDA-based PCIe controllers
# end of PCI controller drivers
# PCI Endpoint
# CONFIG_PCI_ENDPOINT is not set
# end of PCI Endpoint
# PCI switch controller drivers
# CONFIG_PCI_SW_SWITCHTEC is not set
# end of PCI switch controller drivers
# CONFIG_EFI_DISABLE_PCI_DMA is not set
# CONFIG_BLK_DEV_PCIESSD_MTIP32XX is not set
# CONFIG_DW_XDATA_PCIE is not set
# CONFIG_PCI_ENDPOINT_TEST is not set
# CONFIG_MISC_ALCOR_PCI is not set
# CONFIG_MISC_RTSX_PCI is not set
# CONFIG_GP_PCI1XXXX is not set
# CONFIG_SCSI_FDOMAIN_PCI is not set
# CONFIG_PATA_CMD640_PCI is not set
# CONFIG_MACB_PCI is not set
# CONFIG_KSZ884X_PCI is not set
# CONFIG_NE2K_PCI is not set
# CONFIG_CAN_KVASER_PCIEFD is not set
# CONFIG_CAN_CTUCANFD_PCI is not set
# CONFIG_CAN_ESD_402_PCI is not set
# CONFIG_CAN_PEAK_PCIEFD is not set
# CONFIG_ATH5K_PCI is not set
CONFIG_ATH9K_PCI=y
# CONFIG_ATH9K_PCI_NO_EEPROM is not set
CONFIG_B43_PCI_AUTOSELECT=y
CONFIG_B43_PCICORE_AUTOSELECT=y
CONFIG_B43LEGACY_PCI_AUTOSELECT=y
CONFIG_B43LEGACY_PCICORE_AUTOSELECT=y
# CONFIG_BRCMFMAC_PCIE is not set
# CONFIG_P54_PCI is not set
# CONFIG_MWIFIEX_PCIE is not set
# CONFIG_RT2400PCI is not set
# CONFIG_RT2500PCI is not set
# CONFIG_RT61PCI is not set
# CONFIG_RT2800PCI is not set
# CONFIG_QTNFMAC_PCIE is not set
# CONFIG_SERIO_PCIPS2 is not set
CONFIG_SERIAL_8250_PCILIB=y
CONFIG_SERIAL_8250_PCI=y
# CONFIG_SERIAL_8250_PCI1XXXX is not set
CONFIG_XILLYBUS_PCIE=m
# CONFIG_I2C_DESIGNWARE_PCI is not set
# CONFIG_I2C_PCI1XXXX is not set
# CONFIG_SPI_DW_PCI is not set
# CONFIG_SPI_PCI1XXXX is not set
# PCI GPIO expanders
# CONFIG_GPIO_PCI_IDIO_16 is not set
# CONFIG_GPIO_PCIE_IDIO_24 is not set
# end of PCI GPIO expanders
# PCI-based Watchdog Cards
# CONFIG_PCIPCWATCHDOG is not set
# CONFIG_WDTPCI is not set
CONFIG_SSB_PCIHOST_POSSIBLE=y
CONFIG_SSB_PCIHOST=y
CONFIG_SSB_B43_PCI_BRIDGE=y
CONFIG_SSB_DRIVER_PCICORE_POSSIBLE=y
CONFIG_SSB_DRIVER_PCICORE=y
CONFIG_BCMA_HOST_PCI_POSSIBLE=y
CONFIG_BCMA_HOST_PCI=y
CONFIG_BCMA_DRIVER_PCI=y
CONFIG_MEDIA_PCI_SUPPORT=y
# Media digital TV PCI Adapters
# CONFIG_DVB_B2C2_FLEXCOP_PCI is not set
# CONFIG_DVB_SMIPCIE is not set
CONFIG_MEDIA_PCI_HAILO=m
CONFIG_TTPCI_EEPROM=m
CONFIG_SND_PCI=y
# CONFIG_SND_CMIPCI is not set
# CONFIG_SND_YMFPCI is not set
CONFIG_USB_PCI=y
# CONFIG_USB_PCI_AMD is not set
CONFIG_USB_XHCI_PCI=y
CONFIG_USB_XHCI_PCI_RENESAS=m
# CONFIG_USB_DWC2_PCI is not set
# CONFIG_MMC_SDHCI_PCI is not set
# CONFIG_MMC_TOSHIBA_PCI is not set
# CONFIG_DW_DMAC_PCI is not set
# CONFIG_UIO_PCI_GENERIC is not set
# CONFIG_VIRTIO_PCI is not set
# CONFIG_COMMON_CLK_RS9_PCIE is not set
# CONFIG_HISI_PCIE_PMU is not set
# CONFIG_DWC_PCIE_PMU is not set

Code: Select all

pmoore@rpi400:~ $ grep Revision /proc/cpuinfo 
Revision	: c03130

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Wed Apr 09, 2025 6:33 am

You have everything needed for ASPM to be enabled. But it isn't. Has something in userspace disabled it? What's in the file /sys/module/pcie_aspm/parameters/policy?

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Wed Apr 09, 2025 8:58 pm

Hi jdb,

Thanks for the reply. This was a completely fresh installation, I took the latest Raspberry Pi OS 64 bit release and just ran (as root):

Code: Select all

ap-get update
apt-get upgrade
apt full-upgrade
rpi-eeprom-update -a

so there shouldn't be anything bespoke on there.

Code: Select all

pmoore@rpi400:~ $ cat /sys/module/pcie_aspm/parameters/policy 
default performance [powersave] powersupersave 
pmoore@rpi400:~ $

EEPROM options:

Code: Select all

pmoore@rpi400:~ $ sudo rpi-eeprom-config $(sudo rpi-eeprom-update | grep -o '/.*pieeprom.*.bin')
[all]
BOOT_UART=0
WAKE_ON_GPIO=1
POWER_OFF_ON_HALT=0
DHCP_TIMEOUT=45000
DHCP_REQ_TIMEOUT=4000
TFTP_FILE_TIMEOUT=30000
ENABLE_SELF_UPDATE=1
DISABLE_HDMI=0
BOOT_ORDER=0xf421

If you like I can ship my rpi400 and SD card, if it helps...

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Sat Apr 12, 2025 5:06 pm

I dug my own personal Pi 400 out of storage and can confirm - ASPM is "disabled" even on latest rpi-update kernel. Wat.

I can manually enable ASPM with sudo setpci -s 00:00.0 0xbc.B=0x43. But if I write powersave or performance to the pcie_aspm policy sysfs node, I don't see any change in the LnkCtl state.

Rockets are loud.
https://astro-pi.org

jdb: Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator; Posts: 3576; Joined: Thu Jul 11, 2013 2:37 pm

Re: ASPM on rpi 400

Tue Apr 15, 2025 7:41 pm

https://github.com/raspberrypi/linux/pull/6790

I've no idea how long this has been an issue for; if memory serves me right, this is worth about 300mW.

Rockets are loud.
https://astro-pi.org

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Wed Apr 16, 2025 2:30 pm

This is awesome, thanks jdb for the fix! I will try it out tonight.

User avatar pmoore: Posts: 61; Joined: Thu Jun 28, 2018 9:53 am

Re: ASPM on rpi 400

Sat Apr 19, 2025 1:03 pm

Hi jdb,

UPDATE

I have it working, many thanks! I created a fresh installation of the latest 64 bit Raspberry Pi OS and then ran:

Code: Select all

export DEBIAN_FRONTEND=noninteractive
sudo apt-get update
sudo apt-get remove -y realvnc-vnc-server # otherwise it hangs in apt-get upgrade below
sudo apt-get upgrade -y
sudo apt full-upgrade -y
sudo rpi-eeprom-update -a
sudo reboot

After rebooting, I confirmed kernel version is 6.12:

Code: Select all

pmoore@rpi400:~ $ uname -a
Linux rpi400 6.12.20+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.20-1+rpt1~bpo12+1 (2025年03月19日) aarch64 GNU/Linux
pmoore@rpi400:~ $

Then I updated firmware to pick up the ASPM fix and rebooted:

Code: Select all

cd ~/Downloads
curl -fsSL https://github.com/raspberrypi/firmware/archive/refs/heads/master.zip > firmware-master.zip
unzip firmware-master.zip
sudo cp -r firmware-master/boot/* /boot/firmware/
sudo cp -r firmware-master/modules/* /usr/lib/modules/
sudo reboot

After rebooting:

Code: Select all

pmoore@rpi400:~ $ sudo lspci -vvv
00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2711 PCIe Bridge (rev 20) (prog-if 00 [Normal decode])
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 27
	Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
	Memory behind bridge: 00000000-000fffff [size=1M] [32-bit]
	Prefetchable memory behind bridge: 00000000fff00000-00000000000fffff [disabled] [64-bit]
	Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR- NoISA- VGA- VGA16- MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
	Capabilities: [48] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
		Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=1 PME-
	Capabilities: [ac] Express (v2) Root Port (Slot-), MSI 00
		DevCap:	MaxPayload 512 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	CorrErr- NonFatalErr- FatalErr- UnsupReq-
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr+ NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
			ClockPM+ Surprise- LLActRep- BwNot+ ASPMOptComp+
		LnkCtl:	ASPM L1 Enabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt+
		RootCap: CRSVisible+
		RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna+ CRSVisible+
		RootSta: PME ReqID 0000, PMEStatus- PMEPending-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp- 10BitTagReq- OBFF Via WAKE#, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- LN System CLS Not Supported, TPHComp- ExtTPHComp- ARIFwd-
			 AtomicOpsCap: Routing- 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled, ARIFwd-
			 AtomicOpsCtl: ReqEn- EgressBlck-
		LnkCap2: Supported Link Speeds: 2.5-5GT/s, Crosslink- Retimer- 2Retimers- DRS+
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported, DRS-
			 DownstreamComp: Link Down - Not Determined
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
		RootCmd: CERptEn+ NFERptEn+ FERptEn+
		RootSta: CERcvd- MultCERcvd- UERcvd- MultUERcvd-
			 FirstFatal- NonFatalMsg- FatalMsg- IntMsg 0
		ErrorSrc: ERR_COR: 0000 ERR_FATAL/NONFATAL: 0000
	Capabilities: [180 v1] Vendor Specific Information: ID=0000 Rev=0 Len=028 <?>
	Capabilities: [240 v1] L1 PM Substates
		L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
			 PortCommonModeRestoreTime=8us PortTPowerOnTime=10us
		L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
			 T_CommonMode=1us LTR1.2_Threshold=0ns
		L1SubCtl2: T_PwrOn=10us
	Kernel driver in use: pcieport
01:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01) (prog-if 30 [XHCI])
	Subsystem: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller
	Device tree node: /sys/firmware/devicetree/base/scb/pcie@7d500000/pci@0,0/usb@0,0
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 30
	Region 0: Memory at 600000000 (64-bit, non-prefetchable) [size=4K]
	Capabilities: [80] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot-,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [90] MSI: Enable+ Count=4/4 Maskable- 64bit+
		Address: 00000000fffffffc Data: 6540
	Capabilities: [c4] Express (v2) Endpoint, MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
			ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 0W
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr+ NonFatalErr- FatalErr- UnsupReq+ AuxPwr+ TransPend-
		LnkCap:	Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <2us, L1 <16us
			ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp-
		LnkCtl:	ASPM L0s L1 Enabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 5GT/s, Width x1
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
		DevCap2: Completion Timeout: Range B, TimeoutDis+ NROPrPrP- LTR-
			 10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS- TPHComp- ExtTPHComp-
			 AtomicOpsCap: 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- 10BitTagReq- OBFF Disabled,
			 AtomicOpsCtl: ReqEn-
		LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis+
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete- EqualizationPhase1-
			 EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap- ECRCGenEn- ECRCChkCap- ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
	Kernel driver in use: xhci_hcd
pmoore@rpi400:~ $

Here I see ASPM L1 Enabled on Root Complex, and L0S disabled, which looks perfect.

Many thanks jdb!

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