[PATCH] drm/atomic: clarify the rules around drm_atomic_state->allow_modeset

[Dmitry Baryshkov]

On Wed, Jan 08, 2025 at 06:24:16PM +0100, Simona Vetter wrote:
> msm is automagically upgrading normal commits to full modesets, and
> that's a big no-no:
> 
> - for one this results in full on->off->on transitions on all these
>   crtc, at least if you're using the usual helpers. Which seems to be
>   the case, and is breaking uapi
> 
> - further even if the ctm change itself would not result in flicker,
>   this can hide modesets for other reasons. Which again breaks the
>   uapi
> 
> v2: I forgot the case of adding unrelated crtc state. Add that case
> and link to the existing kerneldoc explainers. This has come up in an
> irc discussion with Manasi and Ville about intel's bigjoiner mode.
> Also cc everyone involved in the msm irc discussion, more people
> joined after I sent out v1.
> 
> v3: Wording polish from Pekka and Thomas
> 
> Acked-by: Pekka Paalanen <pekka.paalanen at collabora.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Maxime Ripard <mripard at kernel.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: David Airlie <airlied at gmail.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Pekka Paalanen <pekka.paalanen at collabora.com>
> Cc: Rob Clark <robdclark at gmail.com>
> Cc: Simon Ser <contact at emersion.fr>
> Cc: Manasi Navare <navaremanasi at google.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Abhinav Kumar <quic_abhinavk at quicinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> Signed-off-by: Simona Vetter <simona.vetter at intel.com>
> Signed-off-by: Simona Vetter <simona.vetter at ffwll.ch>
> ---
>  include/drm/drm_atomic.h | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 

Acked-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>

-- 
With best wishes
Dmitry