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

["Murthy, Arun R" <arun.r.murthy@intel.com>]

On 18-03-2026 20:35, Xaver Hugl wrote:
> Hi,
>
> I now have an implementation in KWin:
> https://invent.kde.org/plasma/kwin/-/merge_requests/8991
>
> One thing I noticed is still missing is the catch-all case / unspecified
> error; the "invalid API usage" enum value would be quite misleading for
> that.

Have added the remaining error codes to the enum 
drm_mode_atomic_err_code, will push as part of patchset 11.
/**
  * enum drm_mode_atomic_failure_codes -  error codes for failures in 
atomic_ioctl
  * @DRM_MODE_ATOMIC_INVALID_API_USAGE: invallid API usage(DRM_ATOMIC not
  *                                     enabled, invalid falg, page_flip 
event
  *                                     with test-only, etc)
  * @DRM_MODE_ATOMIC_NEED_FULL_MODESET: Need full modeset on all 
connected crtc's
  * @DRM_MODE_ATOMIC_ASYNC_PROP_CHANGED: Property changed in async flip
  * @DRM_MODE_ATOMIC_SCANOUT_BW: For a given resolution, refresh rate 
and the
  *                              color depth cannot be accomodated. 
Resolution is
  *                              to lower the refresh rate or color depth.
  * @DRM_MODE_ATOMIC_CONNECTOR_BW: Refers to the limitation on the link 
rate on
  *                                a given connector.
  * @DRM_MODE_ATOMIC_PIPE_BW: Limitation on the pipe, either pipe not 
available
  *                           or the pipe scaling factor limitation.
  * @DRM_MODE_ATOMIC_MEMORY_DOMAIN: Any other memory/bandwidth related 
limitation
  *                                 other then the ones specified above.
  * @DRM_MODE_ATOMIC_SPEC_VIOLOATION: Limitation of a particular feature 
on that
  *                                   hardware. To get to know the 
feature, the
  *                                   property/object causing this is 
being sent
  *                                   back to user @failure_objs_ptr in the
  *                                   struct drm_mode_atomic_err_code
  */
enum drm_mode_atomic_failure_codes {
         DRM_MODE_ATOMIC_INVALID_API_USAGE,
         DRM_MODE_ATOMIC_NEED_FULL_MODESET,
         DRM_MODE_ATOMIC_ASYNC_PROP_CHANGED,
         DRM_MODE_ATOMIC_SCANOUT_BW,
         DRM_MODE_ATTOMIC_CONNECTOR_BW,
         DRM_MODE_ATTOMIC_PIPE_BW,
         DRM_MODE_ATOMIC_MEMORY_DOMAIN,
         DRM_MODE_ATOMIC_SPEC_VIOLOATION,
};


As far as the enum INVALID_API_USAGE is concerned, there is a certain 
understanding on the
usage of the atomic_ioctl,  any miss in that would fall in this 
category. Some of them include
     - Driver doesnt support atomic, but still atomic_ioctl being used
     - Invalid/Junk flags
     - Async flip not supported
     - Flag page flip event along with test only is not supported
If changing this INVALID_API_USAGE to UNSPECIFIED_ERROR makes more 
sense, I can change that.

Thanks and Regards,
Arun R Murthy
-------------------

> - Xaver
>