drm/amdgpu: Add amdgpu "max bpc" connector property (v2)

[Why]
Many panels support more than 8bpc but some modes are unavailable while
running at greater than 8bpc due to DP/HDMI bandwidth constraints.

Support for more than 8bpc was added recently in the driver but it
defaults to the maximum supported bpc - locking out these modes.

This should be a user configurable option such that the user can select
what bpc configuration they would like.

[How]
This patch introduces the "max bpc" amdgpu driver specific connector
property so the user can limit the maximum bpc. It ranges from 8 to 16.

This doesn't directly set the preferred bpc for the panel since it
follows Intel's existing driver conventions.

This proprety should be removed once common drm support for max bpc
lands.

v2: rebase on upstream (Alex)

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index 6748cd7fc129b0e7b83966da865f674c676c04e1..686a26de50f91e816471548bf3c1a0fc3f86db86 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -626,6 +626,13 @@ int amdgpu_display_modeset_create_props(struct amdgpu_device *adev)
                                         "dither",
                                         amdgpu_dither_enum_list, sz);
 
+       if (amdgpu_device_has_dc_support(adev)) {
+               adev->mode_info.max_bpc_property =
+                       drm_property_create_range(adev->ddev, 0, "max bpc", 8, 16);
+               if (!adev->mode_info.max_bpc_property)
+                       return -ENOMEM;
+       }
+
        return 0;
 }
 

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
index 11723d8fffbd67fd77591ec03685a732271daa56..0dc2c5c57015947bc98204df4639be5be12b1f09 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
@@ -338,6 +338,8 @@ struct amdgpu_mode_info {
        struct drm_property *audio_property;
        /* FMT dithering */
        struct drm_property *dither_property;
+       /* maximum number of bits per channel for monitor color */
+       struct drm_property *max_bpc_property;
        /* hardcoded DFP edid from BIOS */
        struct edid *bios_hardcoded_edid;
        int bios_hardcoded_edid_size;