Re: [PATCH v10 0/7] User readable error codes on atomic_ioctl failure

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Feb 24, 2026 at 02:24:42PM +0530, Murthy, Arun R wrote:
> On 24-02-2026 14:16, Ville Syrjälä wrote:
> > On Tue, Feb 24, 2026 at 12:46:10PM +0530, Murthy, Arun R wrote:
> >> On 24-02-2026 12:37, Ville Syrjälä wrote:
> >>> On Mon, Feb 23, 2026 at 03:37:39PM +0530, Murthy, Arun R wrote:
> >>>> Any other comments/feedback on this?
> >>> Having random strings as uabi seems like a bad idea.
> >>> How would you make sure those are never changed?
> >> The requirement was to have a string for logging/debugging in the UMD
> >> logs and KMD/display to pass the verbose information.
> >>
> >> Discussions around this.[1][2]
> >>
> >> [1] https://hackmd.io/f3bDn3kyRUalLn4LbMfCVQ#Commit-Failure-Feedback
> >>
> >> [2] https://patchwork.freedesktop.org/patch/666193/?series=152276&rev=1
> > So the enum+obj_id thing there is perhaps the only thing that makes
> > sense for compositors.
> >
> > Although I kinda doubt its actual usefulness to drive useful
> > fallback logic because often the restrictions might be a combination
> > of many things, and the kernel can only realistically report one of
> > those things.
> >
> > Anyways, someone really needs to do the actual compositor
> > implementation so that we could see how any of this would
> > even work in practice.
> Xaver is working on the compositor implementation for KWin and has 
> commented[3] that the API looks good.
> 
> 
> [3] https://patchwork.freedesktop.org/patch/696982/?series=152275&rev=6

Until we see it I don't think there's any point in constantly
spamming this series.

> Thanks and Regards,
> Arun R Murthy
> -------------------
> 
> >> Thanks and Regards,
> >> Arun R Murthy
> >> -------------------
> >>
> >>>> Thanks and Regards,
> >>>> Arun R Murthy
> >>>> -------------------
> >>>>
> >>>> On 23-02-2026 14:45, Arun R Murthy wrote:
> >>>>> EDITME: Imported from f20260210-atomic-v9-5-525c88fd2402@intel.com
> >>>>>            Please review before sending.
> >>>>>
> >>>>> The series focuses on providing a user readable error value on a failure
> >>>>> in drm_atomic_ioctl(). Usually -EINVAL is returned in most of the error
> >>>>> cases and it is difficult for the user to decode the error and get to
> >>>>> know the real cause for the error. If user gets to know the reason for
> >>>>> the error then corrective measurements can be taken up.
> >>>>>
> >>>>> User will have to check for the capability
> >>>>> DRM_CAP_ATOMIC_ERROR_REPORTING before using this feature so as to ensure
> >>>>> that the driver supports failure reporting.
> >>>>>
> >>>>> TODO: driver specific error codes are to be added and will be done in
> >>>>> the follow-up patches.
> >>>>>
> >>>>> TODO: Once the series is merged the element 'reserved' used for sending
> >>>>> the failure code in struct drm_mode_atomic is to changed to err_code.
> >>>>>
> >>>>> The IGT related changes are pushed for review @
> >>>>> https://patchwork.freedesktop.org/series/153330/
> >>>>>
> >>>>> [RFC] changes for libdrm pushed for review @
> >>>>> https://gitlab.freedesktop.org/mesa/libdrm/-/merge_requests/450
> >>>>>
> >>>>>        To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> >>>>>        To: suraj.kandpal@intel.com>
> >>>>>        To: Maxime Ripard <mripard@kernel.org>
> >>>>>        To: Thomas Zimmermann <tzimmermann@suse.de>
> >>>>>        To: David Airlie <airlied@gmail.com>
> >>>>>        To: Simona Vetter <simona@ffwll.ch>
> >>>>>        To: Jani Nikula <jani.nikula@linux.intel.com>
> >>>>>        To: Rodrigo Vivi <rodrigo.vivi@intel.com>
> >>>>>        To: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> >>>>>        To: Tvrtko Ursulin <tursulin@ursulin.net>
> >>>>>        To: xaver.hugl@kde.org
> >>>>>        To: harry.wentland@amd.com
> >>>>>        To: uma.shankar@intel.com
> >>>>>        To: louis.chauvet@bootlin.com
> >>>>>        To: naveen1.kumar@intel.com
> >>>>>        To: ramya.krishna.yella@intel.com
> >>>>>        Cc: dri-devel@lists.freedesktop.org
> >>>>>        Cc: intel-gfx@lists.freedesktop.org
> >>>>>        Cc: intel-xe@lists.freedesktop.org
> >>>>>        Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> >>>>>
> >>>>> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> >>>>> ---
> >>>>> Changes in v9:
> >>>>> - EDITME: describe what is new in this series revision.
> >>>>> - EDITME: use bulletpoints and terse descriptions.
> >>>>> - Link to v8: https://lore.kernel.org/r/20260129-atomic-v8-0-4cb7b0faa051@intel.com
> >>>>>
> >>>>> ---
> >>>>> Arun R Murthy (7):
> >>>>>          drm: Define user readable error codes for atomic ioctl
> >>>>>          drm/atomic: Add error_code element in atomic_state
> >>>>>          drm/atomic: Call complete_signaling only if prepare_signaling is done
> >>>>>          drm/atomic: Allocate atomic_state at the beginning of atomic_ioctl
> >>>>>          drm/atomic: Return user readable error in atomic_ioctl
> >>>>>          drm/i915/display: Error codes for async flip failures
> >>>>>          drm: Introduce DRM_CAP_ATOMIC_ERROR_REPORTING
> >>>>>
> >>>>>     drivers/gpu/drm/drm_atomic.c                 | 31 ++++++++++
> >>>>>     drivers/gpu/drm/drm_atomic_uapi.c            | 89 ++++++++++++++++++++--------
> >>>>>     drivers/gpu/drm/drm_ioctl.c                  |  3 +
> >>>>>     drivers/gpu/drm/i915/display/intel_display.c | 25 ++++----
> >>>>>     include/drm/drm_atomic.h                     | 10 ++++
> >>>>>     include/uapi/drm/drm.h                       |  7 +++
> >>>>>     include/uapi/drm/drm_mode.h                  | 37 ++++++++++++
> >>>>>     7 files changed, 165 insertions(+), 37 deletions(-)
> >>>>> ---
> >>>>> base-commit: cec43d5c2696af219fc2ef71dd7e93db48c80f66
> >>>>> change-id: 20250728-atomic-c9713fd357e4
> >>>>>
> >>>>> Best regards,

-- 
Ville Syrjälä
Intel