linux-kernel - Re: [PATCH v2] usb: xhci: quirk for data loss in ISOC transfers

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Message-ID: <2024111330-crusher-alike-a88d@gregkh>
Date: Wed, 13 Nov 2024 07:05:59 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: "Rangoju, Raju" <raju.rangoju@....com>
Cc: linux-usb@...r.kernel.org, mathias.nyman@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: xhci: quirk for data loss in ISOC transfers

On Tue, Nov 12, 2024 at 07:02:40PM +0530, Rangoju, Raju wrote:
> 
> 
> On 11/12/2024 5:54 PM, Greg KH wrote:
> > On Tue, Nov 12, 2024 at 05:51:04PM +0530, Raju Rangoju wrote:
> > > During the High-Speed Isochronous Audio transfers, xHCI
> > > controller on certain AMD platforms experiences momentary data
> > > loss. This results in Missed Service Errors (MSE) being
> > > generated by the xHCI.
> > > 
> > > The root cause of the MSE is attributed to the ISOC OUT endpoint
> > > being omitted from scheduling. This can happen either when an IN
> > > endpoint with a 64ms service interval is pre-scheduled prior to
> > > the ISOC OUT endpoint or when the interval of the ISOC OUT
> > > endpoint is shorter than that of the IN endpoint. Consequently,
> > > the OUT service is neglected when an IN endpoint with a service
> > > interval exceeding 32ms is scheduled concurrently (every 64ms in
> > > this scenario).
> > > 
> > > This issue is particularly seen on certain older AMD platforms.
> > > To mitigate this problem, it is recommended to adjust the service
> > > interval of the IN endpoint to not exceed 32ms (interval 8). This
> > > adjustment ensures that the OUT endpoint will not be bypassed,
> > > even if a smaller interval value is utilized.
> > > 
> > > Signed-off-by: Raju Rangoju <Raju.Rangoju@....com>
> > 
> > You don't want this backported to any older kernels?  Why not?
> 
> Hi Greg, Yes, backporting is needed, but some of products were released back
> in 2018, not sure of the exact commit id to quote here for backporting as
> there were no precise commits that added this initial support in the first
> place.
> 
> Would you mind tagging it to all stable kernels. Let me know if the patch
> needs to be respinned.

Yes, please resend it with the proper tag, don't ask maintainers to
hand-edit changes for you, that does not scale at all.

thanks,

greg k-h