linux-kernel - Re: [PATCH] usb: host: xhci: Do not re-initialize the XHCI HC if being removed

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Message-ID: <f34927c3-7f23-3971-9f16-88cb5773f973@omp.ru>
Date:   Tue, 23 May 2023 11:45:27 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Wesley Cheng <quic_wcheng@...cinc.com>, <mathias.nyman@...el.com>,
        <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <quic_jackp@...cinc.com>
Subject: Re: [PATCH] usb: host: xhci: Do not re-initialize the XHCI HC if
 being removed

Hello!

On 5/23/23 4:53 AM, Wesley Cheng wrote:

> During XHCI resume, if there was a host controller error detected the
> routine will attempt to re-initialize the XHCI HC, so that it can return
> back to an operational state.  If the XHCI host controller is being
> removed, this sequence would be already handled within the XHCI halt path,
> leading to a duplicate set of reg ops/calls.  In addition, since the XHCI
> bus is being removed, the overhead added in restarting the HCD is
> unnecessary.  Check for the XHC state before setting the reinit_xhc
> parameter, which is responsible for triggering the restart.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
>  drivers/usb/host/xhci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index b81313ffeb76..2017ed3ae4a7 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -1028,7 +1028,8 @@ int xhci_resume(struct xhci_hcd *xhci, pm_message_t msg)
>  	temp = readl(&xhci->op_regs->status);
>  
>  	/* re-initialize the HC on Restore Error, or Host Controller Error */
> -	if (temp & (STS_SRE | STS_HCE)) {
> +	if ((temp & (STS_SRE | STS_HCE)) &&
> +		!(xhci->xhc_state & XHCI_STATE_REMOVING)) {

  Please add one more tab here in order not to blend it with the following lines.

>  		reinit_xhc = true;
>  		if (!xhci->broken_suspend)
>  			xhci_warn(xhci, "xHC error in resume, USBSTS 0x%x, Reinit\n", temp);

MBR, Sergey