On Sun, Jun 25, 2023 at 12:01:12PM +0800, Guiting Shen wrote:

On Fri, Jun 23, 2023 at 23:52:53PM GMT+8, Alan Stern wrote:

quoted

quoted

The comment which was added with commit-id 0365ee0a8f745 may be outdated
because ohci_suspend() and ohci_at91_port_suspend() is used to suspend
instead of setting ohci->rh_state to OHCI_RH_HALTED.

The comment says nothing about ohci->rh_state; it talks about the 
integrated transceivers and the 48 MHz clock.  I don't see why you would 
think the comment is outdated.

The comment says the reason to discard connection state by reset, but I
don't see any reset operation at ohci-at91 suspend/resume routine in
source code.And ohci_suspend() disable irq emission and mark HW
unaccessible  maybe do the same effect as set ohci->rh_state to
OHCI_RH_HALTED to discard connection state which I think the comment is
outdated.

No, it doesn't do the same.  An actual reset is needed.

quoted

quoted

What's more, I found that only ohci-at91 driver to set the ohci->rh_state
which may be unnessory because the ohci_suspend() disable irq emission and
mark HW unaccessible and ohci_at91_port_suspend() suspend the controller.

Is it really need to set ohci->rh_state in ohci_hcd_at91_drv_suspend()?

It maybe confused to set ohci->rh_state to OHCI_RH_SUSPEND in resume
routine.

I'm not really sure what that assignment was intended to accomplish, but 
maybe it was meant to force a reset when the controller resumes.

You could get the same result by leaving ohci->rh_state set to 
OHCI_RH_SUSPENDED but changing ohci_hcd_at91_drv_resume().  Instead of 
calling ohci_resume(hcd, false), have it call:

	ohci_resume(hcd, !ohci_at91->wakeup);

That way, if the wakeup flag is clear and the clock was stopped, 
ohci_resume() will call ohci_usb_reset().  You should also add a comment 
explaining the reason.

I can't test this because I don't have the AT91 hardware.

It works by your methods to force a reset in my sama5d3 soc hardware.
And I found that the ohci->rh_state was already OHCI_RH_SUSPEND before
set it OHCI_RH_HALTED in suspend.So the question is whether to set it
OHCI_RH_HALETED in ohci-at91 suspend routine.

It also works by comment the ohci->rh_state = OHCI_RH_HALTED in suspend
routine.But I think it is safer to use your methods.

Do you have any suggestion on it before I send v2 patch latter.

No suggestions now.  Submit your v2 patch and then maybe I'll have 
something more to say.

Alan Stern

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