Re: [RFC PATCH] USB:XHCI:Modify XHCI driver for USB2.0 controller
From: Mathias Nyman
Date: Fri Feb 26 2021 - 04:24:38 EST
On 26.2.2021 10.21, Longfang Liu wrote:
>
Our current XHCI hardware controller has been customized to only
>
support USB 2.0 ports. When using the current xhci driver, an xhci
>
controller device and an ehci controller device will be created
>
automatically. We want the driver to create only one ehci controller.
>
After modifying the driver as follows, an error will occur.
>
Is there any other modification method?
The xhci driver relies on the existence of both a main and a shared hcd.
One hcd for handing USB 2 (and slower) and the other for USB 3 devices.
As one example xhci_run(hcd) needs to be called for both hcds, first call
sets up things, second one calls xhci_start() that makes the controller run.
It's probably possible to modify the driver to support xHCI hosts with only
USB 2 ports, but requires a lot more work.
>
>
Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx>
>
---
>
drivers/usb/host/xhci-pci.c | 15 ++-------------
>
1 file changed, 2 insertions(+), 13 deletions(-)
>
>
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
>
index ef513c2..7296aad 100644
>
--- a/drivers/usb/host/xhci-pci.c
>
+++ b/drivers/usb/host/xhci-pci.c
>
@@ -364,26 +364,15 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>
/* USB 2.0 roothub is stored in the PCI device now. */
>
hcd = dev_get_drvdata(&dev->dev);
>
xhci = hcd_to_xhci(hcd);
>
- xhci->shared_hcd = usb_create_shared_hcd(&xhci_pci_hc_driver, &dev->dev,
>
- pci_name(dev), hcd);
>
- if (!xhci->shared_hcd) {
>
- retval = -ENOMEM;
>
- goto dealloc_usb2_hcd;
>
- }
>
-
>
+ xhci->shared_hcd = NULL;
>
retval = xhci_ext_cap_init(xhci);
>
if (retval)
>
goto put_usb3_hcd;
>
>
- retval = usb_add_hcd(xhci->shared_hcd, dev->irq,
>
+ retval = usb_add_hcd(xhci->main_hcd, dev->irq,
>
IRQF_SHARED);
>
if (retval)
>
goto put_usb3_hcd;
>
- /* Roothub already marked as USB 3.0 speed */
>
-
>
- if (!(xhci->quirks & XHCI_BROKEN_STREAMS) &&
>
- HCC_MAX_PSA(xhci->hcc_params) >= 4)
>
- xhci->shared_hcd->can_do_streams = 1;
>
>
/* USB-2 and USB-3 roothubs initialized, allow runtime pm suspend */
>
pm_runtime_put_noidle(&dev->dev);
>
Something like the above could of course not be accepted upstream. We can't break existing
functionality to support one modified xHCI.
Thanks
Mathias