Re: [PATCH v1 1/2] drm/msm/dp: Fix support of LTTPR handling

From: Abel Vesa
Date: Tue Mar 11 2025 - 03:22:30 EST

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In reply to: Aleksandrs Vinarskis: "[PATCH v1 1/2] drm/msm/dp: Fix support of LTTPR handling"
Next in thread: Aleksandrs Vinarskis: "[PATCH v1 2/2] drm/msm/dp: Introduce link training per-segment for LTTPRs"
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On 25-03-10 22:05:51, Aleksandrs Vinarskis wrote:
> Take into account LTTPR capabilities when selecting maximum allowed
> link rate, number of data lines. Initialize LTTPR before
> msm_dp_panel_read_sink_caps, as
> a) Link params computation need to take into account LTTPR's caps
> b) It appears DPTX shall (re)read DPRX caps after LTTPR detection
>
> Return lttpr_count to prepare for per-segment link training.
>
> Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@xxxxxxxxx>
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 31 +++++++++++++++++++----------
> drivers/gpu/drm/msm/dp/dp_panel.c | 30 +++++++++++++++++++---------
> drivers/gpu/drm/msm/dp/dp_panel.h | 2 ++
> 3 files changed, 44 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index bbc47d86ae9e..2edbc6adfde5 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -108,6 +108,8 @@ struct msm_dp_display_private {
> struct msm_dp_event event_list[DP_EVENT_Q_MAX];
> spinlock_t event_lock;
>
> + u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE];
> +
> bool wide_bus_supported;
>
> struct msm_dp_audio *audio;
> @@ -367,17 +369,21 @@ static int msm_dp_display_send_hpd_notification(struct msm_dp_display_private *d
> return 0;
> }
>
> -static void msm_dp_display_lttpr_init(struct msm_dp_display_private *dp)
> +static int msm_dp_display_lttpr_init(struct msm_dp_display_private *dp, u8 *dpcd)
> {
> - u8 lttpr_caps[DP_LTTPR_COMMON_CAP_SIZE];
> - int rc;
> + int rc, lttpr_count;
>
> - if (drm_dp_read_lttpr_common_caps(dp->aux, dp->panel->dpcd, lttpr_caps))
> - return;
> + if (drm_dp_read_lttpr_common_caps(dp->aux, dpcd, dp->lttpr_common_caps))
> + return 0;
>
> - rc = drm_dp_lttpr_init(dp->aux, drm_dp_lttpr_count(lttpr_caps));
> - if (rc)
> - DRM_ERROR("failed to set LTTPRs transparency mode, rc=%d\n", rc);
> + lttpr_count = drm_dp_lttpr_count(dp->lttpr_common_caps);
> + rc = drm_dp_lttpr_init(dp->aux, lttpr_count);
> + if (rc) {
> + DRM_ERROR("fialed to set LTTPRs transparency mode, rc=%d\n", rc);

Nitpick: failed

With that fixed, LGTM:

Reviewed-by: Abel Vesa <abel.vesa@xxxxxxxxxx>

> + return 0;
> + }
> +
> + return lttpr_count;
> }
>
> static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
> @@ -385,12 +391,17 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
> struct drm_connector *connector = dp->msm_dp_display.connector;
> const struct drm_display_info *info = &connector->display_info;
> int rc = 0;
> + u8 dpcd[DP_RECEIVER_CAP_SIZE];
>
> - rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
> + rc = drm_dp_read_dpcd_caps(dp->aux, dpcd);
> if (rc)
> goto end;
>
> - msm_dp_display_lttpr_init(dp);
> + msm_dp_display_lttpr_init(dp, dpcd);
> +
> + rc = msm_dp_panel_read_sink_caps(dp->panel, dp->lttpr_common_caps, connector);
> + if (rc)
> + goto end;
>
> msm_dp_link_process_request(dp->link);
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
> index 92415bf8aa16..f41b4cf7002e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
> @@ -45,9 +45,12 @@ static void msm_dp_panel_read_psr_cap(struct msm_dp_panel_private *panel)
> }
> }
>
> -static int msm_dp_panel_read_dpcd(struct msm_dp_panel *msm_dp_panel)
> +static int msm_dp_panel_read_dpcd(struct msm_dp_panel *msm_dp_panel,
> + const u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE])
> {
> int rc;
> + int max_sink_lanes, max_source_lanes, max_lttpr_lanes;
> + int max_sink_rate, max_source_rate, max_lttpr_rate;
> struct msm_dp_panel_private *panel;
> struct msm_dp_link_info *link_info;
> u8 *dpcd, major, minor;
> @@ -64,16 +67,24 @@ static int msm_dp_panel_read_dpcd(struct msm_dp_panel *msm_dp_panel)
> major = (link_info->revision >> 4) & 0x0f;
> minor = link_info->revision & 0x0f;
>
> - link_info->rate = drm_dp_max_link_rate(dpcd);
> - link_info->num_lanes = drm_dp_max_lane_count(dpcd);
> + max_source_lanes = msm_dp_panel->max_dp_lanes;
> + max_source_rate = msm_dp_panel->max_dp_link_rate;
>
> - /* Limit data lanes from data-lanes of endpoint property of dtsi */
> - if (link_info->num_lanes > msm_dp_panel->max_dp_lanes)
> - link_info->num_lanes = msm_dp_panel->max_dp_lanes;
> + max_sink_lanes = drm_dp_max_lane_count(dpcd);
> + max_sink_rate = drm_dp_max_link_rate(dpcd);
> +
> + max_lttpr_lanes = drm_dp_lttpr_max_lane_count(lttpr_common_caps);
> + max_lttpr_rate = drm_dp_lttpr_max_link_rate(lttpr_common_caps);
>
> + if (max_lttpr_lanes)
> + max_sink_lanes = min(max_sink_lanes, max_lttpr_lanes);
> + if (max_lttpr_rate)
> + max_sink_rate = min(max_sink_rate, max_lttpr_rate);
> +
> + /* Limit data lanes from data-lanes of endpoint property of dtsi */
> + link_info->num_lanes = min(max_sink_lanes, max_source_lanes);
> /* Limit link rate from link-frequencies of endpoint property of dtsi */
> - if (link_info->rate > msm_dp_panel->max_dp_link_rate)
> - link_info->rate = msm_dp_panel->max_dp_link_rate;
> + link_info->rate = min(max_sink_rate, max_source_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);
> @@ -109,6 +120,7 @@ static u32 msm_dp_panel_get_supported_bpp(struct msm_dp_panel *msm_dp_panel,
> }
>
> int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> + const u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE],
> struct drm_connector *connector)
> {
> int rc, bw_code;
> @@ -125,7 +137,7 @@ int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> drm_dbg_dp(panel->drm_dev, "max_lanes=%d max_link_rate=%d\n",
> msm_dp_panel->max_dp_lanes, msm_dp_panel->max_dp_link_rate);
>
> - rc = msm_dp_panel_read_dpcd(msm_dp_panel);
> + rc = msm_dp_panel_read_dpcd(msm_dp_panel, lttpr_common_caps);
> if (rc) {
> DRM_ERROR("read dpcd failed %d\n", rc);
> return rc;
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
> index 4906f4f09f24..d89e17a9add5 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.h
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.h
> @@ -7,6 +7,7 @@
> #define _DP_PANEL_H_
>
> #include <drm/msm_drm.h>
> +#include <drm/display/drm_dp_helper.h>
>
> #include "dp_aux.h"
> #include "dp_link.h"
> @@ -49,6 +50,7 @@ int msm_dp_panel_init_panel_info(struct msm_dp_panel *msm_dp_panel);
> int msm_dp_panel_deinit(struct msm_dp_panel *msm_dp_panel);
> int msm_dp_panel_timing_cfg(struct msm_dp_panel *msm_dp_panel);
> int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
> + const u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE],
> struct drm_connector *connector);
> u32 msm_dp_panel_get_mode_bpp(struct msm_dp_panel *msm_dp_panel, u32 mode_max_bpp,
> u32 mode_pclk_khz);
> --
> 2.45.2
>

Next message: Thippeswamy Havalige: "[PATCH] PCI: xilinx-cpm: Fix incorrect version check in init_port"
Previous message: Balbir Singh: "Re: commit 7ffb791423c7 breaks steam game"
In reply to: Aleksandrs Vinarskis: "[PATCH v1 1/2] drm/msm/dp: Fix support of LTTPR handling"
Next in thread: Aleksandrs Vinarskis: "[PATCH v1 2/2] drm/msm/dp: Introduce link training per-segment for LTTPRs"
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