Re: [PATCH v2 1/2] drm/atomic: track individual colorop updates

[Melissa Wen <mwen@igalia.com>]

On 25/03/2026 06:08, Borah, Chaitanya Kumar wrote:
> Hi Melissa,
>
> On 3/23/2026 6:45 PM, Melissa Wen wrote:
>> As we do for CRTC color mgmt properties, use color_mgmt_changed flag to
>> track any value changes in the color pipeline of a given plane, so that
>> drivers can update color blocks as soon as plane color pipeline or
>> individual colorop values change.
>>
>> Reviewed-by: Harry Wentland <harry.wentland@amd.com> #v1
>> Signed-off-by: Melissa Wen <mwen@igalia.com>
>> ---
>>
>>   v2: add linux types to provide bool for MSM driver (kernel bot)
>> ---
>>   drivers/gpu/drm/drm_atomic_uapi.c | 53 ++++++++++++++++++++++++-------
>>   include/drm/drm_atomic_uapi.h     |  4 ++-
>>   2 files changed, 45 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c 
>> b/drivers/gpu/drm/drm_atomic_uapi.c
>> index 87de41fb4459..713fa9e81732 100644
>> --- a/drivers/gpu/drm/drm_atomic_uapi.c
>> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
>> @@ -265,13 +265,19 @@ EXPORT_SYMBOL(drm_atomic_set_fb_for_plane);
>>    *
>>    * Helper function to select the color pipeline on a plane by setting
>>    * it to the first drm_colorop element of the pipeline.
>> + *
>> + * Return: true if plane color pipeline value changed, false otherwise.
>>    */
>> -void
>> +bool
>>   drm_atomic_set_colorop_for_plane(struct drm_plane_state *plane_state,
>>                    struct drm_colorop *colorop)
>>   {
>>       struct drm_plane *plane = plane_state->plane;
>>   +    /* Color pipeline didn't change */
>> +    if (plane_state->color_pipeline == colorop)
>> +        return false;
>> +
>>       if (colorop)
>>           drm_dbg_atomic(plane->dev,
>>                      "Set [COLOROP:%d] for [PLANE:%d:%s] state %p\n",
>> @@ -283,6 +289,8 @@ drm_atomic_set_colorop_for_plane(struct 
>> drm_plane_state *plane_state,
>>                      plane->base.id, plane->name, plane_state);
>>         plane_state->color_pipeline = colorop;
>> +
>> +    return true;
>>   }
>>   EXPORT_SYMBOL(drm_atomic_set_colorop_for_plane);
>>   @@ -600,7 +608,7 @@ static int drm_atomic_plane_set_property(struct 
>> drm_plane *plane,
>>           if (val && !colorop)
>>               return -EACCES;
>>   -        drm_atomic_set_colorop_for_plane(state, colorop);
>> +        state->color_mgmt_changed |= 
>> drm_atomic_set_colorop_for_plane(state, colorop);
>>       } else if (property == config->prop_fb_damage_clips) {
>>           ret = drm_property_replace_blob_from_id(dev,
>>                       &state->fb_damage_clips,
>> @@ -709,11 +717,11 @@ drm_atomic_plane_get_property(struct drm_plane 
>> *plane,
>>   static int drm_atomic_color_set_data_property(struct drm_colorop 
>> *colorop,
>>                             struct drm_colorop_state *state,
>>                             struct drm_property *property,
>> -                          uint64_t val)
>> +                          uint64_t val,
>> +                          bool *replaced)
>>   {
>>       ssize_t elem_size = -1;
>>       ssize_t size = -1;
>> -    bool replaced = false;
>>         switch (colorop->type) {
>>       case DRM_COLOROP_1D_LUT:
>> @@ -735,28 +743,39 @@ static int 
>> drm_atomic_color_set_data_property(struct drm_colorop *colorop,
>>                            &state->data,
>>                            val,
>>                            -1, size, elem_size,
>> -                         &replaced);
>> +                         replaced);
>>   }
>>     static int drm_atomic_colorop_set_property(struct drm_colorop 
>> *colorop,
>>                          struct drm_colorop_state *state,
>>                          struct drm_file *file_priv,
>>                          struct drm_property *property,
>> -                       uint64_t val)
>> +                       uint64_t val,
>> +                       bool *replaced)
>>   {
>>       if (property == colorop->bypass_property) {
>> -        state->bypass = val;
>> +        if (state->bypass != val) {
>> +            state->bypass = val;
>> +            *replaced = true;
>> +        }
>>       } else if (property == colorop->lut1d_interpolation_property) {
>>           colorop->lut1d_interpolation = val;
>>       } else if (property == colorop->curve_1d_type_property) {
>> -        state->curve_1d_type = val;
>> +        if (state->curve_1d_type != val) {
>> +            state->curve_1d_type = val;
>> +            *replaced = true;
>> +        }
>>       } else if (property == colorop->multiplier_property) {
>> -        state->multiplier = val;
>> +        if (state->multiplier != val) {
>> +            state->multiplier = val;
>> +            *replaced = true;
>> +        }
>>       } else if (property == colorop->lut3d_interpolation_property) {
>>           colorop->lut3d_interpolation = val;
>
> I think it would be prudent to add this logic for both the 1dlut and 
> 3dlut interpolation properties. Even though they have just one value 
> exposed right now, that might change in future.

I didn't include interpolations in the color_mgmt_changed logic because 
there is a comment in `include/drm/drm_colorop.h` saying that they are 
read-only.
But thinking better about it, and I think we should not allow 
`drm_atomic_colorop_set_property()` calls to change values of these 
properties if they are read-only.
I didn't track the discussions about what are the plans for these 
properties, how the userspace knows they are read-only properties and 
shouldn't set any value?

>
>>       } else if (property == colorop->data_property) {
>>           return drm_atomic_color_set_data_property(colorop, state,
>> -                              property, val);
>> +                              property, val,
>> +                              replaced);
>>       } else {
>>           drm_dbg_atomic(colorop->dev,
>>                      "[COLOROP:%d:%d] unknown property [PROP:%d:%s]\n",
>> @@ -1273,6 +1292,8 @@ int drm_atomic_set_property(struct 
>> drm_atomic_state *state,
>>       case DRM_MODE_OBJECT_COLOROP: {
>>           struct drm_colorop *colorop = obj_to_colorop(obj);
>>           struct drm_colorop_state *colorop_state;
>> +        struct drm_plane_state *plane_state;
>> +        bool replaced = false;
>>             colorop_state = drm_atomic_get_colorop_state(state, 
>> colorop);
>>           if (IS_ERR(colorop_state)) {
>> @@ -1281,7 +1302,17 @@ int drm_atomic_set_property(struct 
>> drm_atomic_state *state,
>>           }
>>             ret = drm_atomic_colorop_set_property(colorop, 
>> colorop_state,
>> -                              file_priv, prop, prop_value);
>> +                              file_priv, prop, prop_value,
>> +                              &replaced);
>> +        if (ret || !replaced)
>> +            break;
>> +
>> +        plane_state = drm_atomic_get_plane_state(state, 
>> colorop->plane);
>> +        if (IS_ERR(plane_state)) {
>> +            ret = PTR_ERR(plane_state);
>> +            break;
>> +        }
>> +        plane_state->color_mgmt_changed = true;
>
> I am not sure if it was the intention of the uapi design but as I 
> understand there are no guardrails for setting a colorop in an 
> "inactive" pipeline.
>
> So, color_mgmt_changed  is set to true even if a colorop from a color 
> pipeline that is not currently selected(or set to Bypass) by the 
> user-space is changed.
> I guess, the driver needs to be intelligent enough to ignore those 
> colorop but should we reject it at drm core?
>

Thanks for pointing it out, makes sense!
I agree that drm core should reject changes in inactive pipelines.

Melissa


> ==
> Chaitanya
>
>>           break;
>>       }
>>       default:
>> diff --git a/include/drm/drm_atomic_uapi.h 
>> b/include/drm/drm_atomic_uapi.h
>> index 436315523326..4e7e78f711e2 100644
>> --- a/include/drm/drm_atomic_uapi.h
>> +++ b/include/drm/drm_atomic_uapi.h
>> @@ -29,6 +29,8 @@
>>   #ifndef DRM_ATOMIC_UAPI_H_
>>   #define DRM_ATOMIC_UAPI_H_
>>   +#include <linux/types.h>
>> +
>>   struct drm_crtc_state;
>>   struct drm_display_mode;
>>   struct drm_property_blob;
>> @@ -50,7 +52,7 @@ drm_atomic_set_crtc_for_plane(struct 
>> drm_plane_state *plane_state,
>>                     struct drm_crtc *crtc);
>>   void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
>>                    struct drm_framebuffer *fb);
>> -void drm_atomic_set_colorop_for_plane(struct drm_plane_state 
>> *plane_state,
>> +bool drm_atomic_set_colorop_for_plane(struct drm_plane_state 
>> *plane_state,
>>                         struct drm_colorop *colorop);
>>   int __must_check
>>   drm_atomic_set_crtc_for_connector(struct drm_connector_state 
>> *conn_state,
>