Re: [PATCH v2] drm/amd/display: Add pixel encoding info to debugfs

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+ Simon

On 5/22/2024 05:07, Rino André Johnsen wrote:
To be perfectly honest with you, I haven't given that much though. I
used the 'bpc' and 'colorspace' property in debugfs, since I could not
find that information anywhere else. And since I also needed to verify
the pixel encoding being used, I added it where those other values
were. That made for a simple and easy addition for this property.

If you want me to do this differently, let me know. And please point
me to the standardized DRM property where I should expose the values.

Here's a pointer to where the colorspace property is created:

https://github.com/torvalds/linux/blob/v6.9/drivers/gpu/drm/drm_connector.c#L2147

I would expect you can make another property for the information you're looking for and then can get it from userspace using standard property
APIs.


Rino

On Tue, May 21, 2024 at 10:55 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:

On 5/21/2024 15:06, Rino André Johnsen wrote:
What is already there in debugfs is 'bpc' and 'colorspace', but not
the pixel encoding/format.
I have searched high and low for that to be able to verify that my
monitor and computer are using my preferred combination of all those
three values.

I do think it should be available as a standard DRM CRTC property, but
for the time being, I figured that a simple debugfs property would be
sufficient for time being.


It's just about as much work either way to populate it though, why do it
twice instead of just doing it right the first time?

Rino


On Tue, May 21, 2024 at 9:04 PM Christian König
<christian.koenig@xxxxxxx> wrote:

Am 21.05.24 um 07:11 schrieb Rino Andre Johnsen:
[Why]
For debugging and testing purposes.

[How]
Create amdgpu_current_pixelencoding debugfs entry.
Usage: cat /sys/kernel/debug/dri/1/crtc-0/amdgpu_current_pixelencoding

Why isn't that available as standard DRM CRTC property in either sysfs
or debugfs?

I think the format specifiers should already be available somewhere there.

Regards,
Christian.


Signed-off-by: Rino Andre Johnsen <rinoandrejohnsen@xxxxxxxxx>
---

Changes in v2:
1. Do not initialize dm_crtc_state to NULL.
---
    .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 47 +++++++++++++++++++
    1 file changed, 47 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index 27d5c6077630..4254d4a4b56b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -1160,6 +1160,51 @@ static int amdgpu_current_colorspace_show(struct seq_file *m, void *data)
    }
    DEFINE_SHOW_ATTRIBUTE(amdgpu_current_colorspace);

+/*
+ * Returns the current pixelencoding for the crtc.
+ * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/amdgpu_current_pixelencoding
+ */
+static int amdgpu_current_pixelencoding_show(struct seq_file *m, void *data)
+{
+     struct drm_crtc *crtc = m->private;
+     struct drm_device *dev = crtc->dev;
+     struct dm_crtc_state *dm_crtc_state;
+     int res = -ENODEV;
+
+     mutex_lock(&dev->mode_config.mutex);
+     drm_modeset_lock(&crtc->mutex, NULL);
+     if (crtc->state == NULL)
+             goto unlock;
+
+     dm_crtc_state = to_dm_crtc_state(crtc->state);
+     if (dm_crtc_state->stream == NULL)
+             goto unlock;
+
+     switch (dm_crtc_state->stream->timing.pixel_encoding) {
+     case PIXEL_ENCODING_RGB:
+             seq_puts(m, "RGB");
+             break;
+     case PIXEL_ENCODING_YCBCR422:
+             seq_puts(m, "YCBCR422");
+             break;
+     case PIXEL_ENCODING_YCBCR444:
+             seq_puts(m, "YCBCR444");
+             break;
+     case PIXEL_ENCODING_YCBCR420:
+             seq_puts(m, "YCBCR420");
+             break;
+     default:
+             goto unlock;
+     }
+     res = 0;
+
+unlock:
+     drm_modeset_unlock(&crtc->mutex);
+     mutex_unlock(&dev->mode_config.mutex);
+
+     return res;
+}
+DEFINE_SHOW_ATTRIBUTE(amdgpu_current_pixelencoding);

    /*
     * Example usage:
@@ -3688,6 +3733,8 @@ void crtc_debugfs_init(struct drm_crtc *crtc)
                            crtc, &amdgpu_current_bpc_fops);
        debugfs_create_file("amdgpu_current_colorspace", 0644, crtc->debugfs_entry,
                            crtc, &amdgpu_current_colorspace_fops);
+     debugfs_create_file("amdgpu_current_pixelencoding", 0644, crtc->debugfs_entry,
+                         crtc, &amdgpu_current_pixelencoding_fops);
    }

    /*






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