drm/amd/display: Enable DSC over eDP

[why]
- Adding a DM interface to enable DSC over eDP on Linux
- DSC over eDP will allow to power savings by reducing
the bandwidth required to support panel's modes
- Apply link optimization algorithm to reduce link bandwidth
when DSC is enabled

[how]
- Read eDP panel's DSC capabilities
- Apply DSC policy on eDP panel based on its DSC capabilities
- Enable DSC encoder's on the pipe
- Enable DSC on panel's side by setting DSC_ENABLE DPCD register
- Adding link optimization algorithm to reduce link rate or lane
count based

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
index 2d0f1f4a8fff..9c74564cbd8d 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -455,6 +455,7 @@ static bool intersect_dsc_caps(
 	if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
 		dsc_common_caps->bpp_increment_div = min(dsc_common_caps->bpp_increment_div, (uint32_t)8);
 
+	dsc_common_caps->edp_sink_max_bits_per_pixel = dsc_sink_caps->edp_max_bits_per_pixel;
 	dsc_common_caps->is_dp = dsc_sink_caps->is_dp;
 	return true;
 }
@@ -513,6 +514,13 @@ static bool decide_dsc_bandwidth_range(
 			range->min_target_bpp_x16 = preferred_bpp_x16;
 		}
 	}
+	/* TODO - make this value generic to all signal types */
+	else if (dsc_caps->edp_sink_max_bits_per_pixel) {
+		/* apply max bpp limitation from edp sink */
+		range->max_target_bpp_x16 = MIN(dsc_caps->edp_sink_max_bits_per_pixel,
+				max_bpp_x16);
+		range->min_target_bpp_x16 = min_bpp_x16;
+	}
 	else {
 		range->max_target_bpp_x16 = max_bpp_x16;
 		range->min_target_bpp_x16 = min_bpp_x16;