Re: [RFC PATCH 4/6] USB: ehci-omap: Suspend the controller duringbus suspend
From: Felipe Balbi
Date: Wed Jul 03 2013 - 09:16:02 EST
On Wed, Jul 03, 2013 at 04:06:04PM +0300, Roger Quadros wrote:
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On 07/03/2013 03:57 PM, Felipe Balbi wrote:
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> Hi,
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>
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> On Tue, Jul 02, 2013 at 01:17:58PM -0400, Alan Stern wrote:
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>> A PCI-based EHCI controller has two power sources: the core well (which
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>> is turned off during suspend) and the auxiliary well (which remains
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>> powered). That's how remote wakeup works; it uses the auxiliary well.
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>
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> This, kinda, matches what OMAP tries to do with pad wakeup. Just that
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> pad wakeup sits outside of the device itself. Perhaps we could look into
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> how PCI handles the aux well and take some inspiration from there.
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>
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> Any pointers under drivers/pci/ would be great :-)
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>
>
From what I understood, auxiliary well is just a power source, and it keeps
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the EHCI controller powered even during suspend.
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>
If that is true then it is different from our situation as we power down the
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EHCI controller completely.
right but our "auxiliary well" keeps PRCM powered which can wake EHCI up
;-)
What I'm saying is that from ehci-omap's perspective, there's very
little difference, specially since we route the wakeup through the same
IRQ line anyway. Perhaps we could take some inspiration from the PCI
land to make our hwmod/omap_device a little easier from driver
perspective.
Or maybe it doesn't make sense ;-)
--
balbi
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