linux-kernel - Re: nouveau 0000:01:00.0: drm_WARN_ON(!found

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Date:   Wed, 13 Dec 2023 18:37:22 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     Borislav Petkov <bp@...en8.de>, Paul Dufresne <dufresnep@...o.com>,
        Danilo Krummrich <me@...r.org>
Cc:     nouveau <nouveau@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: nouveau 0000:01:00.0: drm_WARN_ON(!found_head)

agh - thank you for repeatedly poking on this, I've been busy enough with GSP
work I totally missed this. Yes - I'm quite surprised that this is blowing up,
but considering that looks to be a GT218 I guess display state readback must
just work a bit differently there since that's really early on into the NV50
days.

The reason that was a drm_WARN_ON() was because it indicates that we're not
reading back OR -> head assignments properly. But, I'm confused how we're even
getting that far on a non-GSP platform. I'm going to dig into this now, but if
I don't figure out a good fix by the end of the day I'll just send a patch to
silent the warning.

Thanks again for bugging me about this!

On Wed, 2023-12-13 at 13:49 +0100, Borislav Petkov wrote:
> On Wed, Dec 13, 2023 at 12:39:36PM +0100, Borislav Petkov wrote:
> > We're getting close to releasing so I guess we either debug this or shut
> > up the WARN.
> 
> Not only that - panic_on_warn turns this into an explosion so you don't
> want that in a released kernel.
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat