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

[Alex Hung <alex.hung@amd.com>]

On 3/25/26 20:13, Melissa Wen wrote:
> 
> 
> 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?

It has been a while but I don't remember that userspace needs to set 
this value, so this can be a mistake. Device driver just need to give a 
supported interpolation that best describes the hardware.

We can remove setting them in drm_atomic_colorop_set_property if 
everybody agrees.

> 
>>
>>>       } 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,
>>
>