linux-kernel - Re: [PATCH v4] usb: ohci: add check for host controller functional states

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Date:   Mon, 20 Dec 2021 16:59:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Yinbo Zhu <zhuyinbo@...ngson.cn>
Cc:     Alan Stern <stern@...land.harvard.edu>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Patchwork Bot <patchwork-bot@...nel.org>
Subject: Re: [PATCH v4] usb: ohci: add check for host controller functional
 states

On Mon, Oct 11, 2021 at 09:02:58PM +0800, Yinbo Zhu wrote:
> The usb states of ohci controller include UsbOperational, UsbReset,
> UsbSuspend and UsbResume. Among them, only the UsbOperational state
> supports launching the start of frame for host controller according
> the ohci protocol spec, but in S3 and S4 (suspend to memory/suspend
> to disk) press test procedure, it may happen that the start of
> frame was launched in other usb states and cause ohci works failed,
> that the phenomenon was hc will allways reproduce the SoF interrupt
> and consider that hc doesn't deal with the ed/td/done list in non-
> UsbOperational, and this patch was to add check for host controller
> functional states and if it is not UsbOperational state that need
> set INTR_SF in intrdisable register to ensure SOF Token generation
> was been disabled so that it can fix ohci SoF abnormally interrupt.

I do not understand this change.  What commit is this fixing?  What
devices today do not work with the code as-is?

> 
> Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
> ---
> Change in v4:
> 		Rework the commit log information.
> 		Remove the extra unnecessary blank line. 
> 
> 
>  drivers/usb/host/ohci-hcd.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
> index 1f5e693..4fd59fa 100644
> --- a/drivers/usb/host/ohci-hcd.c
> +++ b/drivers/usb/host/ohci-hcd.c
> @@ -879,7 +879,7 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
>  {
>  	struct ohci_hcd		*ohci = hcd_to_ohci (hcd);
>  	struct ohci_regs __iomem *regs = ohci->regs;
> -	int			ints;
> +	int			ints, ctl;

New line for a new variable please.

>  
>  	/* Read interrupt status (and flush pending writes).  We ignore the
>  	 * optimization of checking the LSB of hcca->done_head; it doesn't
> @@ -969,9 +969,14 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
>  	 * when there's still unlinking to be done (next frame).
>  	 */
>  	ohci_work(ohci);
> -	if ((ints & OHCI_INTR_SF) != 0 && !ohci->ed_rm_list
> -			&& ohci->rh_state == OHCI_RH_RUNNING)
> +
> +	ctl = ohci_readl(ohci, &regs->control);
> +	if (((ints & OHCI_INTR_SF) != 0 && !ohci->ed_rm_list
> +			&& ohci->rh_state == OHCI_RH_RUNNING) ||
> +			((ctl & OHCI_CTRL_HCFS) != OHCI_USB_OPER)) {
>  		ohci_writel (ohci, OHCI_INTR_SF, &regs->intrdisable);
> +		(void)ohci_readl(ohci, &regs->intrdisable);

No need for (void).

thanks,

greg k-h