Re: [PATCH V8 24/43] drm/amd/display: Skip color pipeline initialization for cursor plane

[Shengyu Qu]

在 2025/4/1 1:42, Alex Hung 写道:

On 3/31/25 11:04, Shengyu Qu wrote:

Or we can add some kind of "linked with" info to plane's COLOR_PIPELINE property, to let userspace know that cursor plane and background plane share the same colorop config. So that userspace could do extra conversion on cursor image data to avoid display wrong cursor color.

That's over-complicate and makes little sense for both device drivers and userspace applications. If any planes share same colorop config, a device driver exposes the same color pipeline with the same colorops. If a plane does not support color pipeline or a driver doesn't want to support it, there is no color pipeline and no color objects.

My understanding is that currently the driver would just report no colorop support on cursor plane and actually implement the background plane's colorop on cursor?

Again it is up to compositors or apps to determine how color pipeline and colorops are used (or not). For example, both primary plane and overlay plane have the same color pipeline, HDR can be enabled only on overlay but not on primary.

Still this is the cleanest way to let compositors know and deal with this special cursor plane behavior. Or if compositors want to use all planes with hw colorop + MPO(for power saving or sth.), they have to detect the gpu they are running on and apply a quirk for this. That's a "dirty" implementation.

在 2025/4/1 0:50, Shengyu Qu 写道:

Thanks, I mistook about the MPO document. Maybe we should also disable colorop on the background plane of the cursor plane? So that compositors would do sw color convertion on both cursor plane and background plane, which should keep cursor display correctly.

Cursor plane has no color pipeline and thus it has no colorop either. It inherits color processing from its parent plane. You can create a color pipeline for cursor plane for your hardware. If none of existing colorop matches your need, new colorop can be defined.

在 2025/4/1 0:34, Alex Hung 写道:

On 3/31/25 10:31, Shengyu Qu wrote:

Sorry for vague expression. I mean that I think we shouldn't register DRM_PLANE_TYPE_CURSOR in the driver, as we don't have actual hardware support.

This is not true. AMD has hardware cursor support.

在 2025/4/1 0:26, Alex Hung 写道:

On 3/31/25 10:12, Shengyu Qu wrote:

So currently we have to hope the compositor won't use DRM_PLANE_TYPE_CURSOR planes at all.... Why do we still register DRM_PLANE_TYPE_CURSOR in the driver?

I am not sure what your question is. A compositor can choose or skip any hardware features, but this discussion is out of the scope.

在 2025/4/1 0:06, Alex Hung 写道:

On 3/31/25 09:43, Shengyu Qu wrote:

Hi,

Thanks for reply. So currently we have to apply color conversion on the background plane of the cursor to do some color space conversion. What would happen if cursor and background plane needs different conversion config? Or we just give the cursor a dedicated plane?

This scenario is not supported on AMD hardware, but software cursors on other plane types won't be affected.

Best regards,
Shengyu

在 2025/3/31 22:28, Alex Hung 写道:

On 3/30/25 06:59, Shengyu Qu wrote:

Hi,

Do we really need to disable cursor plane color pipeline support? I don't think we need to disable that if it is supported, since there might be some user-defined colored cursor icon.

This patch applies to AMD hardware only: https:// elixir.bootlin.com/ linux/v6.13/source/Documentation/gpu/ amdgpu/ display/mpo- overview.rst#L101

Best regards,
Shengyu



在 2025/3/27 7:47, Alex Hung 写道:

For some unknown reason, seems my mail is not shown in the mail list archive, so I resent it.

cursor plane does not need to have color pipeline.

Signed-off-by: Alex Hung <alex.h...@amd.com>
---
v7:
  - Add a commit messages


  1 file changed, 3 insertions(+)


index 9632b8b73e7e..b5b9b0b5da63 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c

      struct drm_prop_enum_list pipelines[MAX_COLOR_PIPELINES];
      int len = 0;
+    if (plane->type == DRM_PLANE_TYPE_CURSOR)
+        return 0;
+
      /* Create COLOR_PIPELINE property and attach */

  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c | 3 +++ diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/ amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/ amdgpu_dm_plane.c @@ -1792,6 +1792,9 @@ dm_plane_init_colorops(struct drm_plane *plane)       drm_plane_create_color_pipeline_property(plane, pipelines, len);

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