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

[Sean Paul]

On Thu, Sep 27, 2018 at 03:53:26PM +0200, Holger Hoffstätte wrote:
> On 09/27/18 15:26, Holger Hoffstätte wrote:
> > On 09/27/18 14:37, Greg Kroah-Hartman wrote:
> > > On Thu, Sep 27, 2018 at 12:43:33PM +0200, Holger Hoffstätte 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.

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

Sean

> 
> -h

-- 
Sean Paul, Software Engineer, Google / Chromium OS