linux-kernel - Re: [PATCH v2] usb: ohci-at91: Fix the unhandle interrupt when resume

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Date:   Sun, 25 Jun 2023 16:04:29 -0400
From:   Alan Stern <stern@...land.harvard.edu>
To:     Guiting Shen <aarongt.shen@...il.com>
Cc:     gregkh@...uxfoundation.org, nicolas.ferre@...rochip.com,
        alexandre.belloni@...tlin.com, claudiu.beznea@...rochip.com,
        linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: ohci-at91: Fix the unhandle interrupt when resume

On Mon, Jun 26, 2023 at 12:15:53AM +0800, Guiting Shen wrote:
> The ohci_hcd_at91_drv_suspend() sets ohci->rh_state to OHCI_RH_HALTED when
> suspend which will let the ohci_irq() skip the interrupt after resume. And
> nobody to handle this interrupt.
> 
> According to the comment in ohci_hcd_at91_drv_suspend(), it need to reset
> when resume from suspend(MEM) to fix.
> 
> Signed-off-by: Guiting Shen <aarongt.shen@...il.com>
> ---
>  drivers/usb/host/ohci-at91.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
> index b9ce8d80f20b..1a0356d9ea15 100644
> --- a/drivers/usb/host/ohci-at91.c
> +++ b/drivers/usb/host/ohci-at91.c
> @@ -672,7 +672,12 @@ ohci_hcd_at91_drv_resume(struct device *dev)
>  	else
>  		at91_start_clock(ohci_at91);
>  
> -	ohci_resume(hcd, false);
> +	/*
> +	 * need to reset according to the comment of suspend routine,
> +	 * otherwise the ohci_irq would skip the interrupt if ohci_state
> +	 * was OHCI_RH_HALTED.
> +	 */
> +	ohci_resume(hcd, !ohci_at91->wakeup);

This comment doesn't say why the code uses !ohci_at91->wakeup.  It 
should explain that.  For example:

	/*
	 * According to the comment in ohci_hcd_at91_drv_suspend()
	 * we need to do a reset if the 48-MHz clock was stopped,
	 * that is, if ohci_at91->wakeup is clear.  Tell ohci_resume()
	 * to reset in this case by setting its "hibernated" flag.
	 */

Alan Stern