Re: [PATCH v2 0/6] drm/vc4: kms: Misc fixes for HVS commits

From: Maxime Ripard <maxime@cerno.tech>
To: Jian-Hong Pan <jhp@endlessos.org>
Cc: Dom Cobley <dom@raspberrypi.com>,
	Tim Gover <tim.gover@raspberrypi.com>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	David Airlie <airlied@linux.ie>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Phil Elwell <phil@raspberrypi.com>
Subject: Re: [PATCH v2 0/6] drm/vc4: kms: Misc fixes for HVS commits
Date: Thu, 18 Nov 2021 11:40:09 +0100	[thread overview]
Message-ID: <20211118104009.jkvkhxi5nh4e4zlp@gilmour> (raw)
In-Reply-To: <CAPpJ_eewp9Z_xdpmB+E_NFH1GGq8oyckVBmS1PD84CvCRUminQ@mail.gmail.com>

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On Thu, Nov 18, 2021 at 02:42:58PM +0800, Jian-Hong Pan wrote:
> Maxime Ripard <maxime@cerno.tech> 於 2021年11月17日 週三 下午5:45寫道：
> > The conversion to DRM commit helpers (f3c420fe19f8, "drm/vc4: kms: Convert to
> > atomic helpers") introduced a number of issues in corner cases, most of them
> > showing themselves in the form of either a vblank timeout or use-after-free
> > error.
> >
> > These patches should fix most of them, some of them still being debugged.
> >
> > Maxime
> >
> > Changes from v1:
> >   - Prevent a null pointer dereference
> >
> > Maxime Ripard (6):
> >   drm/vc4: kms: Wait for the commit before increasing our clock rate
> >   drm/vc4: kms: Fix return code check
> >   drm/vc4: kms: Add missing drm_crtc_commit_put
> >   drm/vc4: kms: Clear the HVS FIFO commit pointer once done
> >   drm/vc4: kms: Don't duplicate pending commit
> >   drm/vc4: kms: Fix previous HVS commit wait
> >
> >  drivers/gpu/drm/vc4/vc4_kms.c | 42 ++++++++++++++++-------------------
> >  1 file changed, 19 insertions(+), 23 deletions(-)
> 
> I tested the v2 patches based on latest mainline kernel with RPi 4B.
> System can boot up into desktop environment.

So the thing that was broken initially isn't anymore?

> Although it still hit the bug [1], which might be under debugging, I
> think these patches LGTM.

The vblank timeout stuff is a symptom of various different bugs. Can you
share your setup, your config.txt, and what you're doing to trigger it?

> [1] https://bugzilla.kernel.org/show_bug.cgi?id=214991
> 
> Tested-by: Jian-Hong Pan <jhp@endlessos.org>

Thanks!
Maxime

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