Re: [PATCH v2 1/4] drm: Define user readable error codes for atomic ioctl

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

On 30-07-2025 16:52, Biju Das wrote:
> Hi Arun,
>
>> -----Original Message-----
>> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of Arun R Murthy
>> Sent: 30 July 2025 11:17
>> Subject: [PATCH v2 1/4] drm: Define user readable error codes for atomic ioctl
>>
>> There can be multiple reasons for a failure in atomic_ioctl. Most often in these error conditions -
>> EINVAL is returned. User/Compositor would have to blindly take a call on failure of this ioctl so as
>> to use ALLOW_MODESET or any. It would be good if user/compositor gets a readable error code on failure
>> so they can take proper corrections in the next commit.
>> The struct drm_mode_atomic is being passed by the user/compositor which holds the properties for
>> modeset/flip. Reusing the same struct for returning the error code in case of failure can save by
>> creating a new uapi/interface for returning the error code.
>> The element 'reserved' in the struct drm_mode_atomic is used for returning the user readable error
>> code.Its a 64bit variable and should suffice 64 error codes that should be sufficient.
>>
>> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
>> ---
>>   include/uapi/drm/drm_mode.h | 40 ++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 40 insertions(+)
>>
>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h index
>> a122bea2559387576150236e3a88f99c24ad3138..87e8f623bfaaab09135be104db04996f0be4dcb4 100644
>> --- a/include/uapi/drm/drm_mode.h
>> +++ b/include/uapi/drm/drm_mode.h
>> @@ -1157,6 +1157,46 @@ struct drm_mode_destroy_dumb {
>>   		DRM_MODE_ATOMIC_NONBLOCK |\
>>   		DRM_MODE_ATOMIC_ALLOW_MODESET)
>>
>> +/* atomic not set in the drm_file */
>> +#define DRM_MODE_ATOMIC_CAP_NOT_ENABLED			BIT(0)
>> +/* atomic flag passed not in DRM_MODE_ATOMIC_FLAGS list */
>> +#define DRM_MODE_ATOMIC_INVALID_FLAG			BIT(1)
>> +/* DRM_MODE_PAGE_FLIP_LEGACY not supported with atomic ioctl  */
>> +#define DRM_MODE_ATOMIC_PAGE_FLIP_ASYNC			BIT(2)
>> +/* flip event with atomic check only not supported */
>> +#define DRM_MODE_ATOMIC_FLIP_EVENT_WITH_CHECKONLY	BIT(3)
>> +/* atomic property change requested need full crtc modeset */
>> +#define DRM_MODE_ATOMIC_CRTC_NEED_FULL_MODESET		BIT(4)
>> +/* atomic property change requested has impact on all connected crtc */
>> +#define DRM_MODE_ATOMIC_NEED_FULL_MODESET		BIT(5)
>> +/* async flip supported on only primary plane */
>> +#define DRM_MODE_ATOMIC_ASYNC_NOT_PRIMARY		BIT(6)
>> +/* modifier not supported by async flip */
>> +#define DRM_MODE_ATOMIC_ASYNC_MODIFIER_NOT_SUPPORTED	BIT(7)
>> +/* async flip with pipe joiner not allowed */
>> +#define DRM_MODE_ATOMIC_ASYNC_PIPEJOINER_NOTALLOWED	BIT(8)
> For consistency, NOTALLOWED->NOT_ALLOWED ??

Sure, will get it correct!

Thanks and Regards,
Arun R Murthy
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