[PATCH v5 3/3] drm/msm/dp: add support of max dp link rate

From: Kuogee Hsieh
Date: Tue Nov 29 2022 - 19:13:26 EST


By default, HBR2 (5.4G) is the max link link be supported. This patch add
the capability to support max link rate at HBR3 (8.1G).

Changes in v2:
-- add max link rate from dtsi

Changes in v3:
-- parser max_data_lanes and max_dp_link_rate from dp_out endpoint

Changes in v4:
-- delete unnecessary pr_err

Changes in v5:
-- split parser function into different patch

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_display.c | 4 ++++
drivers/gpu/drm/msm/dp/dp_panel.c | 7 ++++---
drivers/gpu/drm/msm/dp/dp_panel.h | 1 +
3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 29c9845..4fe2092 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -390,6 +390,10 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
struct edid *edid;

dp->panel->max_dp_lanes = dp->parser->max_dp_lanes;
+ dp->panel->max_dp_link_rate = dp->parser->max_dp_link_rate;
+
+ drm_dbg_dp(dp->drm_dev, "max_lanes=%d max_link_rate=%d\n",
+ dp->panel->max_dp_lanes, dp->panel->max_dp_link_rate);

rc = dp_panel_read_sink_caps(dp->panel, dp->dp_display.connector);
if (rc)
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
index 5149ceb..933fa9c 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -75,12 +75,13 @@ static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
link_info->rate = drm_dp_bw_code_to_link_rate(dpcd[DP_MAX_LINK_RATE]);
link_info->num_lanes = dpcd[DP_MAX_LANE_COUNT] & DP_MAX_LANE_COUNT_MASK;

+ /* Limit data lanes from data-lanes of endpoint properity of dtsi */
if (link_info->num_lanes > dp_panel->max_dp_lanes)
link_info->num_lanes = dp_panel->max_dp_lanes;

- /* Limit support upto HBR2 until HBR3 support is added */
- if (link_info->rate >= (drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4)))
- link_info->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4);
+ /* Limit link rate from link-frequencies of endpoint properity of dtsi */
+ if (link_info->rate > dp_panel->max_dp_link_rate)
+ link_info->rate = dp_panel->max_dp_link_rate;

drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", major, minor);
drm_dbg_dp(panel->drm_dev, "link_rate=%d\n", link_info->rate);
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
index d861197a..f04d021 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.h
+++ b/drivers/gpu/drm/msm/dp/dp_panel.h
@@ -50,6 +50,7 @@ struct dp_panel {

u32 vic;
u32 max_dp_lanes;
+ u32 max_dp_link_rate;

u32 max_bw_code;
};
--
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