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

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Date:   Tue, 23 May 2023 19:42:15 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Greg KH <gregkh@...uxfoundation.org>
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 5/23/23 7:33 PM, Greg KH 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.

   Don't we usually use 2 tabs to indent the continuation lines in the USB code?

> greg k-h

MBR, Sergey