This is a note to let you know that I've just added the patch titled
drm/amd/display: reallocate DET for dual displays with high pixel rate ratio
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-reallocate-det-for-dual-displays-wit.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3fd631e4d64bb4990acfbafe33ba99fed7ecac4d
Author: Samson Tam <Samson.Tam@xxxxxxx>
Date: Tue Feb 28 14:33:00 2023 -0500
drm/amd/display: reallocate DET for dual displays with high pixel rate ratio
[ Upstream commit 5f3401eeb064fab5ce50728cce46532cce7a85c5 ]
[Why]
For dual displays where pixel rate is much higher on one display,
we may get underflow when DET is evenly allocated.
[How]
Allocate less DET segments for the lower pixel rate display and
more DET segments for the higher pixel rate display
Reviewed-by: Alvin Lee <Alvin.Lee2@xxxxxxx>
Acked-by: Qingqing Zhuo <qingqing.zhuo@xxxxxxx>
Signed-off-by: Samson Tam <Samson.Tam@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
index 3a2d7bcc4b6d6..8310bcf651728 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c
@@ -261,6 +261,8 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
return psr_capable;
}
+#define DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER 7
+
/**
* *******************************************************************************************
* dcn32_determine_det_override: Determine DET allocation for each pipe
@@ -272,7 +274,6 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
* If there is a plane that's driven by more than 1 pipe (i.e. pipe split), then the
* number of DET for that given plane will be split among the pipes driving that plane.
*
- *
* High level algorithm:
* 1. Split total DET among number of streams
* 2. For each stream, split DET among the planes
@@ -280,6 +281,18 @@ bool dcn32_is_psr_capable(struct pipe_ctx *pipe)
* among those pipes.
* 4. Assign the DET override to the DML pipes.
*
+ * Special cases:
+ *
+ * For two displays that have a large difference in pixel rate, we may experience
+ * underflow on the larger display when we divide the DET equally. For this, we
+ * will implement a modified algorithm to assign more DET to larger display.
+ *
+ * 1. Calculate difference in pixel rates ( multiplier ) between two displays
+ * 2. If the multiplier exceeds DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER, then
+ * implement the modified DET override algorithm.
+ * 3. Assign smaller DET size for lower pixel display and higher DET size for
+ * higher pixel display
+ *
* @param [in]: dc: Current DC state
* @param [in]: context: New DC state to be programmed
* @param [in]: pipes: Array of DML pipes
@@ -299,18 +312,46 @@ void dcn32_determine_det_override(struct dc *dc,
struct dc_plane_state *current_plane = NULL;
uint8_t stream_count = 0;
+ int phy_pix_clk_mult, lower_mode_stream_index;
+ int phy_pix_clk[MAX_PIPES] = {0};
+ bool use_new_det_override_algorithm = false;
+
for (i = 0; i < context->stream_count; i++) {
/* Don't count SubVP streams for DET allocation */
if (context->streams[i]->mall_stream_config.type != SUBVP_PHANTOM) {
+ phy_pix_clk[i] = context->streams[i]->phy_pix_clk;
stream_count++;
}
}
+ /* Check for special case with two displays, one with much higher pixel rate */
+ if (stream_count == 2) {
+ ASSERT(!phy_pix_clk[0] || !phy_pix_clk[1]);
+ if (phy_pix_clk[0] < phy_pix_clk[1]) {
+ lower_mode_stream_index = 0;
+ phy_pix_clk_mult = phy_pix_clk[1] / phy_pix_clk[0];
+ } else {
+ lower_mode_stream_index = 1;
+ phy_pix_clk_mult = phy_pix_clk[0] / phy_pix_clk[1];
+ }
+
+ if (phy_pix_clk_mult >= DCN3_2_NEW_DET_OVERRIDE_MIN_MULTIPLIER)
+ use_new_det_override_algorithm = true;
+ }
+
if (stream_count > 0) {
stream_segments = 18 / stream_count;
for (i = 0; i < context->stream_count; i++) {
if (context->streams[i]->mall_stream_config.type == SUBVP_PHANTOM)
continue;
+
+ if (use_new_det_override_algorithm) {
+ if (i == lower_mode_stream_index)
+ stream_segments = 4;
+ else
+ stream_segments = 14;
+ }
+
if (context->stream_status[i].plane_count > 0)
plane_segments = stream_segments / context->stream_status[i].plane_count;
else
