This is a note to let you know that I've just added the patch titled
drm/amd/display: Take FEC Overhead into Timeslot Calculation
to the 6.2-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-take-fec-overhead-into-timeslot-calculation.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 68dc1846c3a44d5e633be145c169ce2fd5420695 Mon Sep 17 00:00:00 2001
From: Fangzhi Zuo <Jerry.Zuo@xxxxxxx>
Date: Tue, 28 Feb 2023 21:34:58 -0500
Subject: drm/amd/display: Take FEC Overhead into Timeslot Calculation
From: Fangzhi Zuo <Jerry.Zuo@xxxxxxx>
commit 68dc1846c3a44d5e633be145c169ce2fd5420695 upstream.
8b/10b encoding needs to add 3% fec overhead into the pbn.
In the Synapcis Cascaded MST hub, the first stage MST branch device
needs the information to determine the timeslot count for the
second stage MST branch device. Missing this overhead will leads to
insufficient timeslot allocation.
Cc: stable@xxxxxxxxxxxxxxx
Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Reviewed-by: Hersen Wu <hersenxs.wu@xxxxxxx>
Acked-by: Qingqing Zhuo <qingqing.zhuo@xxxxxxx>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 32 +++++++++---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h | 3 +
2 files changed, 27 insertions(+), 8 deletions(-)
--- 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
@@ -646,12 +646,25 @@ struct dsc_mst_fairness_params {
struct amdgpu_dm_connector *aconnector;
};
-static int kbps_to_peak_pbn(int kbps)
+static uint16_t get_fec_overhead_multiplier(struct dc_link *dc_link)
+{
+ u8 link_coding_cap;
+ uint16_t fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_8B_10B;
+
+ 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 fec_overhead_multiplier_x1000;
+}
+
+static int kbps_to_peak_pbn(int kbps, uint16_t fec_overhead_multiplier_x1000)
{
u64 peak_kbps = kbps;
peak_kbps *= 1006;
- peak_kbps = div_u64(peak_kbps, 1000);
+ 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));
}
@@ -745,11 +758,12 @@ static int increase_dsc_bpp(struct drm_a
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_peak_pbn(params[i].bw_range.max_kbps) - 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 {
@@ -845,6 +859,7 @@ static int try_disable_dsc(struct drm_at
int next_index;
int remaining_to_try = 0;
int ret;
+ uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);
for (i = 0; i < count; i++) {
if (vars[i + k].dsc_enabled
@@ -874,7 +889,7 @@ static int try_disable_dsc(struct drm_at
if (next_index == -1)
break;
- vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps);
+ 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,
@@ -887,7 +902,7 @@ static int try_disable_dsc(struct drm_at
vars[next_index].dsc_enabled = false;
vars[next_index].bpp_x16 = 0;
} else {
- vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.max_kbps);
+ vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.max_kbps, fec_overhead_multiplier_x1000);
ret = drm_dp_atomic_find_time_slots(state,
params[next_index].port->mgr,
params[next_index].port,
@@ -916,6 +931,7 @@ static int compute_mst_dsc_configs_for_l
int count = 0;
int i, k, ret;
bool debugfs_overwrite = false;
+ uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);
memset(params, 0, sizeof(params));
@@ -977,7 +993,7 @@ static int compute_mst_dsc_configs_for_l
/* Try no compression */
for (i = 0; i < count; i++) {
vars[i + k].aconnector = params[i].aconnector;
- vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
+ 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,
@@ -996,7 +1012,7 @@ static int compute_mst_dsc_configs_for_l
/* Try max compression */
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_peak_pbn(params[i].bw_range.min_kbps);
+ 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,
@@ -1004,7 +1020,7 @@ static int compute_mst_dsc_configs_for_l
if (ret < 0)
return ret;
} else {
- vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
+ 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,
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h
@@ -46,6 +46,9 @@
#define SYNAPTICS_CASCADED_HUB_ID 0x5A
#define IS_SYNAPTICS_CASCADED_PANAMERA(devName, data) ((IS_SYNAPTICS_PANAMERA(devName) && ((int)data[2] == SYNAPTICS_CASCADED_HUB_ID)) ? 1 : 0)
+#define PBN_FEC_OVERHEAD_MULTIPLIER_8B_10B 1031
+#define PBN_FEC_OVERHEAD_MULTIPLIER_128B_132B 1000
+
struct amdgpu_display_manager;
struct amdgpu_dm_connector;
Patches currently in stable-queue which might be from Jerry.Zuo@xxxxxxx are
queue-6.2/drm-amd-display-add-dsc-support-for-synaptics-cascaded-mst-hub.patch
queue-6.2/drm-amd-display-take-fec-overhead-into-timeslot-calculation.patch
