[PATCH 6.10] drm/amd/display: Refactor function dm_dp_mst_is_port_support_mode()

Kevin Holm
2024-07-30T18:53:47Z

From: Wayne Lin <wayne.lin@amd.com>

[ Upstream commit fa57924c76d995e87ca3533ec60d1d5e55769a27 ]

[Why]
dm_dp_mst_is_port_support_mode() is a bit not following the original design rule and cause
light up issue with multiple 4k monitors after mst dsc hub.

[How]
Refactor function dm_dp_mst_is_port_support_mode() a bit to solve the light up issue.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[kevin@holm.dev: Resolved merge conflict in .../amdgpu_dm_mst_types.c]
Fixes: 4df96ba6676034 ("drm/amd/display: Add timing pixel encoding for mst mode validation")
Link: https://lore.kernel.org/stable/d74a7768e957e6ce88c27a5bece0c64dff132e24@holm.dev/T/#u
Signed-off-by: Kevin Holm <kevin@holm.dev>
---
I resolved the merge conflict so that, after this patch is applied to the
linux-6.10.y branch of the stable git repository, the resulting function
dm_dp_mst_is_port_support_mode (and also the new function
dp_get_link_current_set_bw) is identical to the original commit.

I've confirmed that it fixes the regression I reported for my use case.
---
.../display/amdgpu_dm/amdgpu_dm_mst_types.c | 232 +++++++++++-------
1 file changed, 147 insertions(+), 85 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index a5e1a93ddaea..e90f9d697511 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -1595,109 +1595,171 @@ static bool is_dsc_common_config_possible(struct dc_stream_state *stream,
return bw_range->max_target_bpp_x16 && bw_range->min_target_bpp_x16;
}

+#if defined(CONFIG_DRM_AMD_DC_FP)
+static bool dp_get_link_current_set_bw(struct drm_dp_aux *aux, uint32_t *cur_link_bw)
+{
+ uint32_t total_data_bw_efficiency_x10000 = 0;
+ uint32_t link_rate_per_lane_kbps = 0;
+ enum dc_link_rate link_rate;
+ union lane_count_set lane_count;
+ u8 dp_link_encoding;
+ u8 link_bw_set = 0;
+
+ *cur_link_bw = 0;
+
+ if (drm_dp_dpcd_read(aux, DP_MAIN_LINK_CHANNEL_CODING_SET, &dp_link_encoding, 1) != 1 ||
+ drm_dp_dpcd_read(aux, DP_LANE_COUNT_SET, &lane_count.raw, 1) != 1 ||
+ drm_dp_dpcd_read(aux, DP_LINK_BW_SET, &link_bw_set, 1) != 1)
+ return false;
+
+ switch (dp_link_encoding) {
+ case DP_8b_10b_ENCODING:
+ link_rate = link_bw_set;
+ link_rate_per_lane_kbps = link_rate * LINK_RATE_REF_FREQ_IN_KHZ * BITS_PER_DP_BYTE;
+ total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_8b_10b_x10000;
+ total_data_bw_efficiency_x10000 /= 100;
+ total_data_bw_efficiency_x10000 *= DATA_EFFICIENCY_8b_10b_FEC_EFFICIENCY_x100;
+ break;
+ case DP_128b_132b_ENCODING:
+ switch (link_bw_set) {
+ case DP_LINK_BW_10:
+ link_rate = LINK_RATE_UHBR10;
+ break;
+ case DP_LINK_BW_13_5:
+ link_rate = LINK_RATE_UHBR13_5;
+ break;
+ case DP_LINK_BW_20:
+ link_rate = LINK_RATE_UHBR20;
+ break;
+ default:
+ return false;
+ }
+
+ link_rate_per_lane_kbps = link_rate * 10000;
+ total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_128b_132b_x10000;
+ break;
+ default:
+ return false;
+ }
+
+ *cur_link_bw = link_rate_per_lane_kbps * lane_count.bits.LANE_COUNT_SET / 10000 * total_data_bw_efficiency_x10000;
+ return true;
+}
+#endif
+
enum dc_status dm_dp_mst_is_port_support_mode(
struct amdgpu_dm_connector *aconnector,
struct dc_stream_state *stream)
{
- int pbn, branch_max_throughput_mps = 0;
+#if defined(CONFIG_DRM_AMD_DC_FP)
+ int branch_max_throughput_mps = 0;
struct dc_link_settings cur_link_settings;
- unsigned int end_to_end_bw_in_kbps = 0;
- unsigned int upper_link_bw_in_kbps = 0, down_link_bw_in_kbps = 0;
+ uint32_t end_to_end_bw_in_kbps = 0;
+ uint32_t root_link_bw_in_kbps = 0;
+ uint32_t virtual_channel_bw_in_kbps = 0;
struct dc_dsc_bw_range bw_range = {0};
struct dc_dsc_config_options dsc_options = {0};
+ uint32_t stream_kbps;

- /*
- * Consider the case with the depth of the mst topology tree is equal or less than 2
- * A. When dsc bitstream can be transmitted along the entire path
- * 1. dsc is possible between source and branch/leaf device (common dsc params is possible), AND
- * 2. dsc passthrough supported at MST branch, or
- * 3. dsc decoding supported at leaf MST device
- * Use maximum dsc compression as bw constraint
- * B. When dsc bitstream cannot be transmitted along the entire path
- * Use native bw as bw constraint
+ /* DSC unnecessary case
+ * Check if timing could be supported within end-to-end BW
*/
- if (is_dsc_common_config_possible(stream, &bw_range) &&
- (aconnector->mst_output_port->passthrough_aux ||
- aconnector->dsc_aux == &aconnector->mst_output_port->aux)) {
- cur_link_settings = stream->link->verified_link_cap;
- upper_link_bw_in_kbps = dc_link_bandwidth_kbps(aconnector->dc_link, &cur_link_settings);
- down_link_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn);
-
- /* pick the end to end bw bottleneck */
- end_to_end_bw_in_kbps = min(upper_link_bw_in_kbps, down_link_bw_in_kbps);
-
- if (end_to_end_bw_in_kbps < bw_range.min_kbps) {
- DRM_DEBUG_DRIVER("maximum dsc compression cannot fit into end-to-end bandwidth\n");
+ stream_kbps =
+ dc_bandwidth_in_kbps_from_timing(&stream->timing,
+ dc_link_get_highest_encoding_format(stream->link));
+ cur_link_settings = stream->link->verified_link_cap;
+ root_link_bw_in_kbps = dc_link_bandwidth_kbps(aconnector->dc_link, &cur_link_settings);
+ virtual_channel_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn);
+
+ /* pick the end to end bw bottleneck */
+ end_to_end_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps);
+
+ if (stream_kbps <= end_to_end_bw_in_kbps) {
+ DRM_DEBUG_DRIVER("No DSC needed. End-to-end bw sufficient.");
+ return DC_OK;
+ }
+
+ /*DSC necessary case*/
+ if (!aconnector->dsc_aux)
+ return DC_FAIL_BANDWIDTH_VALIDATE;
+
+ if (is_dsc_common_config_possible(stream, &bw_range)) {
+
+ /*capable of dsc passthough. dsc bitstream along the entire path*/
+ if (aconnector->mst_output_port->passthrough_aux) {
+ if (bw_range.min_kbps > end_to_end_bw_in_kbps) {
+ DRM_DEBUG_DRIVER("DSC passthrough. Max dsc compression can't fit into end-to-end bw\n");
return DC_FAIL_BANDWIDTH_VALIDATE;
- }
+ }
+ } else {
+ /*dsc bitstream decoded at the dp last link*/
+ struct drm_dp_mst_port *immediate_upstream_port = NULL;
+ uint32_t end_link_bw = 0;
+
+ /*Get last DP link BW capability*/
+ if (dp_get_link_current_set_bw(&aconnector->mst_output_port->aux, &end_link_bw)) {
+ if (stream_kbps > end_link_bw) {
+ DRM_DEBUG_DRIVER("DSC decode at last link. Mode required bw can't fit into available bw\n");
+ return DC_FAIL_BANDWIDTH_VALIDATE;
+ }
+ }

- if (end_to_end_bw_in_kbps < bw_range.stream_kbps) {
- dc_dsc_get_default_config_option(stream->link->dc, &dsc_options);
- dsc_options.max_target_bpp_limit_override_x16 = aconnector->base.display_info.max_dsc_bpp * 16;
- if (dc_dsc_compute_config(stream->sink->ctx->dc->res_pool->dscs[0],
- &stream->sink->dsc_caps.dsc_dec_caps,
- &dsc_options,
- end_to_end_bw_in_kbps,
- &stream->timing,
- dc_link_get_highest_encoding_format(stream->link),
- &stream->timing.dsc_cfg)) {
- stream->timing.flags.DSC = 1;
- DRM_DEBUG_DRIVER("end-to-end bandwidth require dsc and dsc config found\n");
- } else {
- DRM_DEBUG_DRIVER("end-to-end bandwidth require dsc but dsc config not found\n");
- return DC_FAIL_BANDWIDTH_VALIDATE;
+ /*Get virtual channel bandwidth between source and the link before the last link*/
+ if (aconnector->mst_output_port->parent->port_parent)
+ immediate_upstream_port = aconnector->mst_output_port->parent->port_parent;
+
+ if (immediate_upstream_port) {
+ virtual_channel_bw_in_kbps = kbps_from_pbn(immediate_upstream_port->full_pbn);
+ virtual_channel_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps);
+ if (bw_range.min_kbps > virtual_channel_bw_in_kbps) {
+ DRM_DEBUG_DRIVER("DSC decode at last link. Max dsc compression can't fit into MST available bw\n");
+ return DC_FAIL_BANDWIDTH_VALIDATE;
+ }
}
}
- } else {
- /* Check if mode could be supported within max slot
- * number of current mst link and full_pbn of mst links.
- */
- int pbn_div, slot_num, max_slot_num;
- enum dc_link_encoding_format link_encoding;
- uint32_t stream_kbps =
- dc_bandwidth_in_kbps_from_timing(&stream->timing,
- dc_link_get_highest_encoding_format(stream->link));
-
- pbn = kbps_to_peak_pbn(stream_kbps);
- pbn_div = dm_mst_get_pbn_divider(stream->link);
- slot_num = DIV_ROUND_UP(pbn, pbn_div);
-
- link_encoding = dc_link_get_highest_encoding_format(stream->link);
- if (link_encoding == DC_LINK_ENCODING_DP_8b_10b)
- max_slot_num = 63;
- else if (link_encoding == DC_LINK_ENCODING_DP_128b_132b)
- max_slot_num = 64;
- else {
- DRM_DEBUG_DRIVER("Invalid link encoding format\n");
- return DC_FAIL_BANDWIDTH_VALIDATE;
- }

- if (slot_num > max_slot_num ||
- pbn > aconnector->mst_output_port->full_pbn) {
- DRM_DEBUG_DRIVER("Mode can not be supported within mst links!");
+ /*Confirm if we can obtain dsc config*/
+ dc_dsc_get_default_config_option(stream->link->dc, &dsc_options);
+ dsc_options.max_target_bpp_limit_override_x16 = aconnector->base.display_info.max_dsc_bpp * 16;
+ if (dc_dsc_compute_config(stream->sink->ctx->dc->res_pool->dscs[0],
+ &stream->sink->dsc_caps.dsc_dec_caps,
+ &dsc_options,
+ end_to_end_bw_in_kbps,
+ &stream->timing,
+ dc_link_get_highest_encoding_format(stream->link),
+ &stream->timing.dsc_cfg)) {
+ stream->timing.flags.DSC = 1;
+ DRM_DEBUG_DRIVER("Require dsc and dsc config found\n");
+ } else {
+ DRM_DEBUG_DRIVER("Require dsc but can't find appropriate dsc config\n");
return DC_FAIL_BANDWIDTH_VALIDATE;
}
- }

- /* check is mst dsc output bandwidth branch_overall_throughput_0_mps */
- switch (stream->timing.pixel_encoding) {
- case PIXEL_ENCODING_RGB:
- case PIXEL_ENCODING_YCBCR444:
- branch_max_throughput_mps =
- aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_0_mps;
- break;
- case PIXEL_ENCODING_YCBCR422:
- case PIXEL_ENCODING_YCBCR420:
- branch_max_throughput_mps =
- aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_1_mps;
- break;
- default:
- break;
- }
+ /* check is mst dsc output bandwidth branch_overall_throughput_0_mps */
+ switch (stream->timing.pixel_encoding) {
+ case PIXEL_ENCODING_RGB:
+ case PIXEL_ENCODING_YCBCR444:
+ branch_max_throughput_mps =
+ aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_0_mps;
+ break;
+ case PIXEL_ENCODING_YCBCR422:
+ case PIXEL_ENCODING_YCBCR420:
+ branch_max_throughput_mps =
+ aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_1_mps;
+ break;
+ default:
+ break;
+ }

- if (branch_max_throughput_mps != 0 &&
- ((stream->timing.pix_clk_100hz / 10) > branch_max_throughput_mps * 1000))
+ if (branch_max_throughput_mps != 0 &&
+ ((stream->timing.pix_clk_100hz / 10) > branch_max_throughput_mps * 1000)) {
+ DRM_DEBUG_DRIVER("DSC is required but max throughput mps fails");
return DC_FAIL_BANDWIDTH_VALIDATE;
-
+ }
+ } else {
+ DRM_DEBUG_DRIVER("DSC is required but can't find common dsc config.");
+ return DC_FAIL_BANDWIDTH_VALIDATE;
+ }
+#endif
return DC_OK;
}
--
2.45.2