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Revert "drm/amd/display: Fix pbn to kbps Conversion" 

Deeply daisy chained DP/MST displays are no longer able to light
up. This reverts commit e0dec00f3d ("drm/amd/display: Fix pbn
to kbps Conversion")

Cc: Jerry Zuo <jerry.zuo@amd.com>
Reported-by: nat@nullable.se
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4756
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e1c94109c76e8a77a21531bd53f6c63356c81158)
Cc: stable@vger.kernel.org # 6.17+
master
Mario Limonciello 2025-12-09 11:14:47 -06:00 committed by Alex Deucher
parent 93a01629c8
commit 72e24456a5
1 changed files with 36 additions and 23 deletions
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59
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
View File

@ -884,28 +884,26 @@ struct dsc_mst_fairness_params {
};
#if defined(CONFIG_DRM_AMD_DC_FP)
static uint64_t kbps_to_pbn(int kbps, bool is_peak_pbn)
static uint16_t get_fec_overhead_multiplier(struct dc_link *dc_link)
{
uint64_t effective_kbps = (uint64_t)kbps;
u8 link_coding_cap;
uint16_t fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_8B_10B;
if (is_peak_pbn) { // add 0.6% (1006/1000) overhead into effective kbps
effective_kbps *= 1006;
effective_kbps = div_u64(effective_kbps, 1000);
}
link_coding_cap = dc_link_dp_mst_decide_link_encoding_format(dc_link);
if (link_coding_cap == DP_128b_132b_ENCODING)
fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_128B_132B;
return (uint64_t) DIV64_U64_ROUND_UP(effective_kbps * 64, (54 * 8 * 1000));
return fec_overhead_multiplier_x1000;
}
static uint32_t pbn_to_kbps(unsigned int pbn, bool with_margin)
static int kbps_to_peak_pbn(int kbps, uint16_t fec_overhead_multiplier_x1000)
{
uint64_t pbn_effective = (uint64_t)pbn;
u64 peak_kbps = kbps;
if (with_margin) // deduct 0.6% (994/1000) overhead from effective pbn
pbn_effective *= (1000000 / PEAK_FACTOR_X1000);
else
pbn_effective *= 1000;
return DIV_U64_ROUND_UP(pbn_effective * 8 * 54, 64);
peak_kbps *= 1006;
peak_kbps *= fec_overhead_multiplier_x1000;
peak_kbps = div_u64(peak_kbps, 1000 * 1000);
return (int) DIV64_U64_ROUND_UP(peak_kbps * 64, (54 * 8 * 1000));
}
static void set_dsc_configs_from_fairness_vars(struct dsc_mst_fairness_params *params,
@ -976,7 +974,7 @@ static int bpp_x16_from_pbn(struct dsc_mst_fairness_params param, int pbn)
dc_dsc_get_default_config_option(param.sink->ctx->dc, &dsc_options);
dsc_options.max_target_bpp_limit_override_x16 = drm_connector->display_info.max_dsc_bpp * 16;
kbps = pbn_to_kbps(pbn, false);
kbps = div_u64((u64)pbn * 994 * 8 * 54, 64);
dc_dsc_compute_config(
param.sink->ctx->dc->res_pool->dscs[0],
&param.sink->dsc_caps.dsc_dec_caps,
@ -1005,11 +1003,12 @@ static int increase_dsc_bpp(struct drm_atomic_state *state,
int link_timeslots_used;
int fair_pbn_alloc;
int ret = 0;
uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);
for (i = 0; i < count; i++) {
if (vars[i + k].dsc_enabled) {
initial_slack[i] =
kbps_to_pbn(params[i].bw_range.max_kbps, false) - vars[i + k].pbn;
kbps_to_peak_pbn(params[i].bw_range.max_kbps, fec_overhead_multiplier_x1000) - vars[i + k].pbn;
bpp_increased[i] = false;
remaining_to_increase += 1;
} else {
@ -1105,6 +1104,7 @@ static int try_disable_dsc(struct drm_atomic_state *state,
int next_index;
int remaining_to_try = 0;
int ret;
uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);
int var_pbn;
for (i = 0; i < count; i++) {
@ -1137,7 +1137,7 @@ static int try_disable_dsc(struct drm_atomic_state *state,
DRM_DEBUG_DRIVER("MST_DSC index #%d, try no compression\n", next_index);
var_pbn = vars[next_index].pbn;
vars[next_index].pbn = kbps_to_pbn(params[next_index].bw_range.stream_kbps, true);
vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps, fec_overhead_multiplier_x1000);
ret = drm_dp_atomic_find_time_slots(state,
params[next_index].port->mgr,
params[next_index].port,
@ -1197,6 +1197,7 @@ static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
int count = 0;
int i, k, ret;
bool debugfs_overwrite = false;
uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);
struct drm_connector_state *new_conn_state;
memset(params, 0, sizeof(params));
@ -1277,7 +1278,7 @@ static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
DRM_DEBUG_DRIVER("MST_DSC Try no compression\n");
for (i = 0; i < count; i++) {
vars[i + k].aconnector = params[i].aconnector;
vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.stream_kbps, false);
vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000);
vars[i + k].dsc_enabled = false;
vars[i + k].bpp_x16 = 0;
ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port,
@ -1299,7 +1300,7 @@ static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
DRM_DEBUG_DRIVER("MST_DSC Try max compression\n");
for (i = 0; i < count; i++) {
if (params[i].compression_possible && params[i].clock_force_enable != DSC_CLK_FORCE_DISABLE) {
vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.min_kbps, false);
vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.min_kbps, fec_overhead_multiplier_x1000);
vars[i + k].dsc_enabled = true;
vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16;
ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr,
@ -1307,7 +1308,7 @@ static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
if (ret < 0)
return ret;
} else {
vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.stream_kbps, false);
vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000);
vars[i + k].dsc_enabled = false;
vars[i + k].bpp_x16 = 0;
ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr,
@ -1762,6 +1763,18 @@ clean_exit:
return ret;
}
static uint32_t kbps_from_pbn(unsigned int pbn)
{
uint64_t kbps = (uint64_t)pbn;
kbps *= (1000000 / PEAK_FACTOR_X1000);
kbps *= 8;
kbps *= 54;
kbps /= 64;
return (uint32_t)kbps;
}
static bool is_dsc_common_config_possible(struct dc_stream_state *stream,
struct dc_dsc_bw_range *bw_range)
{
@ -1860,7 +1873,7 @@ enum dc_status dm_dp_mst_is_port_support_mode(
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 = pbn_to_kbps(aconnector->mst_output_port->full_pbn, true);
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);
@ -1913,7 +1926,7 @@ enum dc_status dm_dp_mst_is_port_support_mode(
immediate_upstream_port = aconnector->mst_output_port->parent->port_parent;
if (immediate_upstream_port) {
virtual_channel_bw_in_kbps = pbn_to_kbps(immediate_upstream_port->full_pbn, true);
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);
} else {
/* For topology LCT 1 case - only one mstb*/