Hello,
Den 2026-05-18 kl. 11:30, skrev Borah, Chaitanya Kumar:
>
>
> On 5/6/2026 1:31 AM, Maarten Lankhorst wrote:
>> Gen9 platforms allow CRTC's to be programmed with a background/canvas
>> color below the programmable planes. Let's expose this as a property to
>> allow userspace to program a desired value.
>>
>> This patch is based on earlier work by Chandra Konduru and Matt Roper.
>> Between 2018 and now, intel/display has changed so much that another
>> rewrite was necessary.
>>
>> v2:
>> - Set initial background color (black) via proper helper function (Bob)
>> - Fix debugfs output
>> - General rebasing
>> v3 (Maarten):
>> - Rebase on top of recent changes.
>> v4 (Maarten):
>> - Complete rewrite based on the solution that went upstream, and
>> on the new intel color management features.
>>
>> Cc: Chandra Konduru <[email protected]>
>> Cc: [email protected]
>> Co-developed-by: Matt Roper <[email protected]>
>> Signed-off-by: Maarten Lankhorst <[email protected]>
>> ---
>> Corresponding IGT: https://patchwork.freedesktop.org/series/166016/
>>
>> drivers/gpu/drm/i915/display/intel_color.c | 47 ++++++++++++-------
>> drivers/gpu/drm/i915/display/intel_color.h | 3 ++
>> drivers/gpu/drm/i915/display/intel_crtc.c | 4 ++
>> drivers/gpu/drm/i915/display/intel_display.c | 5 ++
>> .../drm/i915/display/intel_display_debugfs.c | 6 +++
>> .../drm/i915/display/intel_display_types.h | 1 +
>> .../drm/i915/display/intel_modeset_setup.c | 2 +
>> 7 files changed, 52 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_color.c
>> b/drivers/gpu/drm/i915/display/intel_color.c
>> index 0531c60e5e5d5..2365cf06cd514 100644
>> --- a/drivers/gpu/drm/i915/display/intel_color.c
>> +++ b/drivers/gpu/drm/i915/display/intel_color.c
>> @@ -1102,19 +1102,37 @@ static void skl_get_config(struct intel_crtc_state
>> *crtc_state)
>> {
>> struct intel_display *display = to_intel_display(crtc_state);
>> struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> + u32 color;
>> crtc_state->gamma_mode = hsw_read_gamma_mode(crtc);
>> crtc_state->csc_mode = ilk_read_csc_mode(crtc);
>> + color = intel_de_read(display, SKL_BOTTOM_COLOR(crtc->pipe));
>> if (DISPLAY_VER(display) < 35) {
>> - u32 tmp = intel_de_read(display, SKL_BOTTOM_COLOR(crtc->pipe));
>> -
>> - if (tmp & SKL_BOTTOM_COLOR_GAMMA_ENABLE)
>> + if (color & SKL_BOTTOM_COLOR_GAMMA_ENABLE)
>> crtc_state->gamma_enable = true;
>> - if (tmp & SKL_BOTTOM_COLOR_CSC_ENABLE)
>> + if (color & SKL_BOTTOM_COLOR_CSC_ENABLE)
>> crtc_state->csc_enable = true;
>> }
>> +
>> + crtc_state->hw.background_color = color & GENMASK(29, 0);
>> +}
>> +
>> +u32 intel_color_hw_background_color(u64 drm_background_color)
>> +{
>> + return (DRM_ARGB64_GETR_BPC(drm_background_color, 10) << 20) |
>> + (DRM_ARGB64_GETG_BPC(drm_background_color, 10) << 10) |
>> + (DRM_ARGB64_GETB_BPC(drm_background_color, 10));
>> +}
>> +
>> +u64 intel_color_drm_background_color(u32 hw_background_color)
>> +{
>> + uint16_t r = (hw_background_color >> 20) & 0x3ff;
>> + uint16_t g = (hw_background_color >> 10) & 0x3ff;
>> + uint16_t b = hw_background_color & 0x3ff;
>> +
>> + return DRM_ARGB64_PREP_BPC(0x3ff, r, g, b, 10);
>> }
>
> nit:
> Better names?
>
> intel_color_background_color_drm_to_hw
> intel_color_background_color_hw_to_drm
>
> Stick to kernel types u16?
>
>> static void skl_color_commit_arm(struct intel_dsb *dsb,
>> @@ -1123,16 +1141,11 @@ static void skl_color_commit_arm(struct intel_dsb
>> *dsb,
>> struct intel_display *display = to_intel_display(crtc_state);
>> struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> enum pipe pipe = crtc->pipe;
>> - u32 val = 0;
>> + u32 val = crtc_state->hw.background_color;
>> if (crtc_state->has_psr)
>> ilk_load_csc_matrix(dsb, crtc_state);
>> - /*
>> - * We don't (yet) allow userspace to control the pipe background color,
>> - * so force it to black, but apply pipe gamma and CSC appropriately
>> - * so that its handling will match how we program our planes.
>> - */
>> if (crtc_state->gamma_enable)
>> val |= SKL_BOTTOM_COLOR_GAMMA_ENABLE;
>> if (crtc_state->csc_enable)
>> @@ -1151,11 +1164,7 @@ static void icl_color_commit_arm(struct intel_dsb
>> *dsb,
>> struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> enum pipe pipe = crtc->pipe;
>> - /*
>> - * We don't (yet) allow userspace to control the pipe background color,
>> - * so force it to black.
>> - */
>> - intel_de_write_dsb(display, dsb, SKL_BOTTOM_COLOR(pipe), 0);
>> + intel_de_write_dsb(display, dsb, SKL_BOTTOM_COLOR(pipe),
>> crtc_state->hw.background_color);
>> intel_de_write_dsb(display, dsb, GAMMA_MODE(crtc->pipe),
>> crtc_state->gamma_mode);
>> @@ -2107,9 +2116,15 @@ int intel_color_check(struct intel_atomic_state
>> *state,
>> * May need to update pipe gamma enable bits
>> * when C8 planes are getting enabled/disabled.
>> */
>> - if (!old_crtc_state->c8_planes != !new_crtc_state->c8_planes)
>> + if (!old_crtc_state->c8_planes != !new_crtc_state->c8_planes ||
>> + old_crtc_state->hw.background_color !=
>> new_crtc_state->hw.background_color)
>> new_crtc_state->uapi.color_mgmt_changed = true;
>> + if (DRM_ARGB64_GETA(new_crtc_state->uapi.background_color) != 0xffff)
>> {
>> + drm_dbg_kms(display->drm, "New background not completely opaque\n");
>> + return -EINVAL;
>> + }
>> +
>
> can be within a old != new check, not to invoke it unconditionally.
The check we have above checks hw.background_color old vs new, the value
programmed
into the hardware without alpha component.
This check is about uapi.background_color which does have the alpha component.
I can put it in a new vs old check, but it would have to be a separate one and
there is no benefit to having 2 comparisons vs 1.
>
>> if (!intel_crtc_needs_color_update(new_crtc_state))
>> return 0;
>> diff --git a/drivers/gpu/drm/i915/display/intel_color.h
>> b/drivers/gpu/drm/i915/display/intel_color.h
>> index c21b9bdf7bb8a..f2cbce57b63d7 100644
>> --- a/drivers/gpu/drm/i915/display/intel_color.h
>> +++ b/drivers/gpu/drm/i915/display/intel_color.h
>> @@ -47,4 +47,7 @@ void intel_color_plane_program_pipeline(struct intel_dsb
>> *dsb,
>> void intel_color_plane_commit_arm(struct intel_dsb *dsb,
>> const struct intel_plane_state *plane_state);
>> bool intel_color_crtc_has_3dlut(struct intel_display *display, enum pipe
>> pipe);
>> +u32 intel_color_hw_background_color(u64 drm_background_color);
>> +u64 intel_color_drm_background_color(u32 hw_background_color);
>> +
>> #endif /* __INTEL_COLOR_H__ */
>> diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c
>> b/drivers/gpu/drm/i915/display/intel_crtc.c
>> index 03de219f7a645..b7600cecafc85 100644
>> --- a/drivers/gpu/drm/i915/display/intel_crtc.c
>> +++ b/drivers/gpu/drm/i915/display/intel_crtc.c
>> @@ -7,6 +7,7 @@
>> #include <linux/slab.h>
>> #include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_blend.h>
>> #include <drm/drm_fourcc.h>
>> #include <drm/drm_plane.h>
>> #include <drm/drm_print.h>
>> @@ -405,6 +406,9 @@ static int __intel_crtc_init(struct intel_display
>> *display, enum pipe pipe)
>> BIT(DRM_SCALING_FILTER_DEFAULT) |
>> BIT(DRM_SCALING_FILTER_NEAREST_NEIGHBOR));
>> + if (DISPLAY_VER(display) >= 9)
>> + drm_crtc_attach_background_color_property(&crtc->base);
>> +
>> intel_color_crtc_init(crtc);
>> intel_drrs_crtc_init(crtc);
>> intel_crtc_crc_init(crtc);
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
>> b/drivers/gpu/drm/i915/display/intel_display.c
>> index 2fa10f8582794..306908f20b5a0 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -4505,6 +4505,8 @@ intel_crtc_copy_uapi_to_hw_state_nomodeset(struct
>> intel_atomic_state *state,
>> crtc_state->uapi.gamma_lut);
>> drm_property_replace_blob(&crtc_state->hw.ctm,
>> crtc_state->uapi.ctm);
>> + crtc_state->hw.background_color =
>> + intel_color_hw_background_color(crtc_state->uapi.background_color);
>> }
>> static void
>> @@ -4544,6 +4546,7 @@ copy_joiner_crtc_state_nomodeset(struct
>> intel_atomic_state *state,
>> primary_crtc_state->hw.gamma_lut);
>> drm_property_replace_blob(&secondary_crtc_state->hw.ctm,
>> primary_crtc_state->hw.ctm);
>> + secondary_crtc_state->hw.background_color =
>> primary_crtc_state->hw.background_color;
>> secondary_crtc_state->uapi.color_mgmt_changed =
>> primary_crtc_state->uapi.color_mgmt_changed;
>> }
>> @@ -5356,6 +5359,8 @@ intel_pipe_config_compare(const struct
>> intel_crtc_state *current_config,
>> else
>> PIPE_CONF_CHECK_X(csc_mode);
>> PIPE_CONF_CHECK_BOOL(gamma_enable);
>> +
>> + PIPE_CONF_CHECK_X(hw.background_color);
>> PIPE_CONF_CHECK_BOOL(csc_enable);
>> PIPE_CONF_CHECK_BOOL(wgc_enable);
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> index 81bef000a4e3e..336ef29d0c5b5 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> @@ -572,6 +572,12 @@ static void intel_crtc_info(struct seq_file *m, struct
>> intel_crtc *crtc)
>> intel_scaler_info(m, crtc);
>> + if (DISPLAY_VER(display) >= 9) {
>> + u32 background = crtc_state->hw.background_color;
>> +
>> + seq_printf(m, "\tbackground color (10bpc XRGB210101010): %08x\n",
>> background);
>
> Typo: XRGB2101010
>
> ==
> Chaitanya
>
Oops, missed that one!
Kind regards,
~Maarten Lankhorst
>> + }
>> +
>> if (crtc_state->joiner_pipes)
>> seq_printf(m, "\tLinked to 0x%x pipes as a %s\n",
>> crtc_state->joiner_pipes,
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
>> b/drivers/gpu/drm/i915/display/intel_display_types.h
>> index c819167618502..aa07be41648c4 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>> @@ -1034,6 +1034,7 @@ struct intel_crtc_state {
>> /* logical state of LUTs */
>> struct drm_property_blob *degamma_lut, *gamma_lut, *ctm;
>> struct drm_display_mode mode, pipe_mode, adjusted_mode;
>> + u32 background_color;
>> enum drm_scaling_filter scaling_filter;
>> u8 sharpness_strength;
>> } hw;
>> diff --git a/drivers/gpu/drm/i915/display/intel_modeset_setup.c
>> b/drivers/gpu/drm/i915/display/intel_modeset_setup.c
>> index 4c646b1bd0ee0..d3b2433eae791 100644
>> --- a/drivers/gpu/drm/i915/display/intel_modeset_setup.c
>> +++ b/drivers/gpu/drm/i915/display/intel_modeset_setup.c
>> @@ -334,6 +334,8 @@ static void intel_crtc_copy_hw_to_uapi_state(struct
>> intel_crtc_state *crtc_state
>> crtc_state->uapi.adjusted_mode = crtc_state->hw.adjusted_mode;
>> crtc_state->uapi.scaling_filter = crtc_state->hw.scaling_filter;
>> crtc_state->uapi.sharpness_strength =
>> crtc_state->hw.sharpness_strength;
>> + crtc_state->uapi.background_color =
>> + intel_color_drm_background_color(crtc_state->hw.background_color);
>> if (DISPLAY_INFO(display)->color.degamma_lut_size) {
>> /* assume 1:1 mapping */
>
