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drm/amd/display: lttpr cap should be nrd cap in bw_alloc mode

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[WHY]
When bw allocation mode enabled, dpia may reports lttpr cap with
reduced common cap. It would cause driver not start pre-training with
max available bandwidth.

[How]
When bw allocation mode enabled, use NRD cap as lttpr cap.

Reviewed-by: Cruise Hung <cruise.hung@amd.com>
Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Peichen Huang <PeiChen.Huang@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Peichen Huang
2025-09-11 13:41:16 +08:00
committed by Alex Deucher
parent 6d92c4d030
commit 13ab3a8f9a
1 changed files with 36 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
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@@ -424,6 +424,21 @@ static enum dc_link_rate get_link_rate_from_max_link_bw(
return link_rate;
}
static enum dc_lane_count get_lttpr_max_lane_count(struct dc_link *link)
{
enum dc_lane_count lttpr_max_lane_count = LANE_COUNT_UNKNOWN;
if (link->dpcd_caps.lttpr_caps.max_lane_count <= LANE_COUNT_DP_MAX)
lttpr_max_lane_count = link->dpcd_caps.lttpr_caps.max_lane_count;
/* if bw_allocation is enabled and nrd_max_lane_count is set, use it */
if (link->dpia_bw_alloc_config.bw_alloc_enabled &&
link->dpia_bw_alloc_config.nrd_max_lane_count > 0)
lttpr_max_lane_count = link->dpia_bw_alloc_config.nrd_max_lane_count;
return lttpr_max_lane_count;
}
static enum dc_link_rate get_lttpr_max_link_rate(struct dc_link *link)
{
@@ -438,6 +453,11 @@ static enum dc_link_rate get_lttpr_max_link_rate(struct dc_link *link)
break;
}
/* if bw_allocation is enabled and nrd_max_link_rate is set, use it */
if (link->dpia_bw_alloc_config.bw_alloc_enabled &&
link->dpia_bw_alloc_config.nrd_max_link_rate > 0)
lttpr_max_link_rate = link->dpia_bw_alloc_config.nrd_max_link_rate;
if (link->dpcd_caps.lttpr_caps.supported_128b_132b_rates.bits.UHBR20)
lttpr_max_link_rate = LINK_RATE_UHBR20;
else if (link->dpcd_caps.lttpr_caps.supported_128b_132b_rates.bits.UHBR13_5)
@@ -2241,6 +2261,7 @@ const struct dc_link_settings *dp_get_verified_link_cap(
struct dc_link_settings dp_get_max_link_cap(struct dc_link *link)
{
struct dc_link_settings max_link_cap = {0};
enum dc_lane_count lttpr_max_lane_count;
enum dc_link_rate lttpr_max_link_rate;
enum dc_link_rate cable_max_link_rate;
struct resource_context *res_ctx = &link->dc->current_state->res_ctx;
@@ -2305,8 +2326,11 @@ struct dc_link_settings dp_get_max_link_cap(struct dc_link *link)
/* Some LTTPR devices do not report valid DPCD revisions, if so, do not take it's link cap into consideration. */
if (link->dpcd_caps.lttpr_caps.revision.raw >= DPCD_REV_14) {
if (link->dpcd_caps.lttpr_caps.max_lane_count < max_link_cap.lane_count)
max_link_cap.lane_count = link->dpcd_caps.lttpr_caps.max_lane_count;
lttpr_max_lane_count = get_lttpr_max_lane_count(link);
if (lttpr_max_lane_count < max_link_cap.lane_count)
max_link_cap.lane_count = lttpr_max_lane_count;
lttpr_max_link_rate = get_lttpr_max_link_rate(link);
if (lttpr_max_link_rate < max_link_cap.link_rate)
@@ -2412,6 +2436,11 @@ bool dp_verify_link_cap_with_retries(
dp_trace_detect_lt_init(link);
DC_LOG_HW_LINK_TRAINING("%s: Link[%d] LinkRate=0x%x LaneCount=%d",
__func__, link->link_index,
known_limit_link_setting->link_rate,
known_limit_link_setting->lane_count);
if (link->link_enc && link->link_enc->features.flags.bits.DP_IS_USB_C &&
link->dc->debug.usbc_combo_phy_reset_wa)
apply_usbc_combo_phy_reset_wa(link, known_limit_link_setting);
@@ -2448,6 +2477,11 @@ bool dp_verify_link_cap_with_retries(
dp_trace_lt_fail_count_update(link, fail_count, true);
dp_trace_set_lt_end_timestamp(link, true);
DC_LOG_HW_LINK_TRAINING("%s: Link[%d] Exit. is_success=%d fail_count=%d",
__func__, link->link_index,
success,
fail_count);
return success;
}