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

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Message-ID: <2023052303-dreaded-professed-d259@gregkh>
Date:   Tue, 23 May 2023 17:33:22 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Sergey Shtylyov <s.shtylyov@....ru>
Cc:     Wesley Cheng <quic_wcheng@...cinc.com>, mathias.nyman@...el.com,
        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

On Tue, May 23, 2023 at 11:45:27AM +0300, Sergey Shtylyov wrote:
> 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.

Ick, no, please do not do that, it needs to move left instead.

greg k-h