Re: [PATCH 4.18 74/88] drm/atomic: Use drm_drv_uses_atomic_modeset() for debugfs creation

From: Holger HoffstÃtte
Date: Thu Sep 27 2018 - 10:18:31 EST


On 09/27/18 16:05, Sean Paul wrote:
On Thu, Sep 27, 2018 at 03:53:26PM +0200, Holger HoffstÃtte wrote:
On 09/27/18 15:26, Holger HoffstÃtte wrote:
On 09/27/18 14:37, Greg Kroah-Hartman wrote:
On Thu, Sep 27, 2018 at 12:43:33PM +0200, Holger HoffstÃtte wrote:
On 09/27/18 11:03, Greg Kroah-Hartman wrote:
4.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Lyude Paul <lyude@xxxxxxxxxx>

commit 3c499ea0c662e2f38aafbd4f516b08aab8cfa0e5 upstream.

As pointed out by Daniel Vetter, we should be usinng
drm_drv_uses_atomic_modeset() for determining whether or not we want to
make the debugfs nodes for atomic instead of checking DRIVER_ATOMIC, as
the former isn't an accurate representation of whether or not the driver
is actually using atomic modesetting internally (even though it might
not be exposing atomic capabilities).

Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20180917173733.21293-1-lyude@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

This patch breaks switching the console to high resolution during boot on my
workstation with a Radeon card; it worked fine with 4.18.10 and reverting it
fixes the problem:

Is 4.19-rc5 also a problem?


No, 4.19-rc5 with the same config works fine and properly switches the
console during boot.

Interestingly another machine with i915 chip seemed to work fine with this
patch included (rebooted that one first), so it might well be related to
different motherboard/chipset or the Radeon card (an admittedly old, but
otherwise completely functional fanless r600).

I'll try to find more clues, but for now that's all I got.

Looking at mainline include/drm I see several recent movements and cleanups
related to drm_drv_uses_atomic_modeset(), moving it out of drmP.h and into
drm, changes to atomic modesetting and such, all part of the 4.19 merge
window. I'm reasonably sure some relatred changes went missing here wrt.
this patch.

Hey all,
Thanks for testing, Holger.

This was fixed with https://patchwork.freedesktop.org/patch/250350/ which is not
Cc stable.

That's what I just looked at, it's in mainline as well. I briefly considered
backporting that fix manually, but was not sure why radeon is apparently not
a "modesetting driver" and figured I'd rather wait for someone who understands
drm better than me.

I think it'd be best to just drop the initial patch from stable, it
doesn't need to go back afaict.

Agreed - using 4.18.11 just fine right now without it. :)

cheers,
Holger