Re: [PATCH v4 2/2] drm/msm/dp: enable widebus feature for display port

From: Bjorn Andersson
Date: Mon Feb 14 2022 - 23:22:17 EST

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In reply to: Kuogee Hsieh: "[PATCH v4 2/2] drm/msm/dp: enable widebus feature for display port"
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On Mon 14 Feb 16:39 CST 2022, Kuogee Hsieh wrote:

> Widebus feature will transmit two pixel data per pixel clock to interface.
> This feature now is required to be enabled to easy migrant to higher
> resolution applications in future. However since some legacy chipsets
> does not support this feature, this feature is enabled base on chip's
> hardware revision.
>
> changes in v2:
> -- remove compression related code from timing
> -- remove op_info from struct msm_drm_private
> -- remove unnecessary wide_bus_en variables
> -- pass wide_bus_en into timing configuration by struct msm_dp
>
> Changes in v3:
> -- split patch into 3 patches
> -- enable widebus feature base on chip hardware revision
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>

Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 4 +++-
> drivers/gpu/drm/msm/dp/dp_catalog.c | 36 +++++++++++++++++++++++++++--
> drivers/gpu/drm/msm/dp/dp_catalog.h | 3 ++-
> drivers/gpu/drm/msm/dp/dp_ctrl.c | 13 +++++++----
> drivers/gpu/drm/msm/dp/dp_ctrl.h | 1 +
> drivers/gpu/drm/msm/dp/dp_display.c | 30 ++++++++++++++++++++++++
> drivers/gpu/drm/msm/dp/dp_display.h | 2 ++
> drivers/gpu/drm/msm/dp/dp_panel.c | 4 ++--
> drivers/gpu/drm/msm/dp/dp_panel.h | 2 +-
> drivers/gpu/drm/msm/msm_drv.h | 6 +++++
> 10 files changed, 90 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 0c22839..b2d23c2 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -2167,8 +2167,10 @@ int dpu_encoder_setup(struct drm_device *dev, struct drm_encoder *enc,
> timer_setup(&dpu_enc->vsync_event_timer,
> dpu_encoder_vsync_event_handler,
> 0);
> - else if (disp_info->intf_type == DRM_MODE_ENCODER_TMDS)
> + else if (disp_info->intf_type == DRM_MODE_ENCODER_TMDS) {
> dpu_enc->dp = priv->dp[disp_info->h_tile_instance[0]];
> + dpu_enc->wide_bus_en = msm_dp_wide_bus_enable(dpu_enc->dp);
> + }
>
> INIT_DELAYED_WORK(&dpu_enc->delayed_off_work,
> dpu_encoder_off_work);
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c
> index 64f0b26..99d087e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
> @@ -483,6 +483,27 @@ int dp_catalog_ctrl_set_pattern_state_bit(struct dp_catalog *dp_catalog,
> }
>
> /**
> + * dp_catalog_hw_revision() - retrieve DP hw revision
> + *
> + * @dp_catalog: DP catalog structure
> + *
> + * return: u32

Q: What's 2+2?
A: Integer

This should say:

Return: the controller hardware revision

> + *
> + * This function return the DP controller hw revision

That's what "Return:" in the kernel-doc is supposed to clarify...

https://docs.kernel.org/doc-guide/kernel-doc.html is good to read.

> + *
> + */
> +u32 dp_catalog_hw_revision(struct dp_catalog *dp_catalog)
> +{
> + u32 revision;
> + struct dp_catalog_private *catalog = container_of(dp_catalog,
> + struct dp_catalog_private, dp_catalog);
> +
> + revision = dp_read_ahb(catalog, REG_DP_HW_VERSION);

There's no need for a local variable here, just:

return dp_read_ahb();

> +
> + return revision;
> +}
> +
> +/**
> * dp_catalog_ctrl_reset() - reset DP controller
> *
> * @dp_catalog: DP catalog structure
> @@ -739,10 +760,11 @@ u32 dp_catalog_ctrl_read_phy_pattern(struct dp_catalog *dp_catalog)
> }
>
> /* panel related catalog functions */
> -int dp_catalog_panel_timing_cfg(struct dp_catalog *dp_catalog)
> +int dp_catalog_panel_timing_cfg(struct dp_catalog *dp_catalog, bool wide_bus_en)
> {
> struct dp_catalog_private *catalog = container_of(dp_catalog,
> struct dp_catalog_private, dp_catalog);
> + u32 reg;
>
> dp_write_link(catalog, REG_DP_TOTAL_HOR_VER,
> dp_catalog->total);
> @@ -751,7 +773,17 @@ int dp_catalog_panel_timing_cfg(struct dp_catalog *dp_catalog)
> dp_write_link(catalog, REG_DP_HSYNC_VSYNC_WIDTH_POLARITY,
> dp_catalog->width_blanking);
> dp_write_link(catalog, REG_DP_ACTIVE_HOR_VER, dp_catalog->dp_active);
> - dp_write_p0(catalog, MMSS_DP_INTF_CONFIG, 0);
> +
> + reg = dp_read_p0(catalog, MMSS_DP_INTF_CONFIG);
> +
> + if (wide_bus_en)
> + reg |= BIT(4); /* DATABUS_WIDEN */

#define DATABUS_WIDEN BIT(4)

Would save you the need for writing that comment.

> + else
> + reg &= ~BIT(4);
> +
> + DRM_DEBUG_DP("wide_bus_en=%d reg=%x\n", wide_bus_en, reg);
> +
> + dp_write_p0(catalog, MMSS_DP_INTF_CONFIG, reg);
> return 0;
> }
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.h b/drivers/gpu/drm/msm/dp/dp_catalog.h
> index 7dea101..a3a0129 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.h
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.h
> @@ -95,6 +95,7 @@ void dp_catalog_ctrl_config_misc(struct dp_catalog *dp_catalog, u32 cc, u32 tb);
> void dp_catalog_ctrl_config_msa(struct dp_catalog *dp_catalog, u32 rate,
> u32 stream_rate_khz, bool fixed_nvid);
> int dp_catalog_ctrl_set_pattern_state_bit(struct dp_catalog *dp_catalog, u32 pattern);
> +u32 dp_catalog_hw_revision(struct dp_catalog *dp_catalog);
> void dp_catalog_ctrl_reset(struct dp_catalog *dp_catalog);
> bool dp_catalog_ctrl_mainlink_ready(struct dp_catalog *dp_catalog);
> void dp_catalog_ctrl_enable_irq(struct dp_catalog *dp_catalog, bool enable);
> @@ -115,7 +116,7 @@ void dp_catalog_ctrl_send_phy_pattern(struct dp_catalog *dp_catalog,
> u32 dp_catalog_ctrl_read_phy_pattern(struct dp_catalog *dp_catalog);
>
> /* DP Panel APIs */
> -int dp_catalog_panel_timing_cfg(struct dp_catalog *dp_catalog);
> +int dp_catalog_panel_timing_cfg(struct dp_catalog *dp_catalog, bool wide_bus_en);
> void dp_catalog_dump_regs(struct dp_catalog *dp_catalog);
> void dp_catalog_panel_tpg_enable(struct dp_catalog *dp_catalog,
> struct drm_display_mode *drm_mode);
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 245e1b9..1c4cf9d 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -154,7 +154,7 @@ static void dp_ctrl_config_ctrl(struct dp_ctrl_private *ctrl)
> dp_catalog_ctrl_config_ctrl(ctrl->catalog, config);
> }
>
> -static void dp_ctrl_configure_source_params(struct dp_ctrl_private *ctrl)
> +static void dp_ctrl_configure_source_params(struct dp_ctrl_private *ctrl, bool wide_bus_en)
> {
> u32 cc, tb;
>
> @@ -167,7 +167,7 @@ static void dp_ctrl_configure_source_params(struct dp_ctrl_private *ctrl)
> ctrl->panel->dp_mode.bpp);
> cc = dp_link_get_colorimetry_config(ctrl->link);
> dp_catalog_ctrl_config_misc(ctrl->catalog, cc, tb);
> - dp_panel_timing_cfg(ctrl->panel);
> + dp_panel_timing_cfg(ctrl->panel, wide_bus_en);
> }
>
> /*
> @@ -1796,6 +1796,7 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
> int ret = 0;
> bool mainlink_ready = false;
> struct dp_ctrl_private *ctrl;
> + u32 pixel_rate_orig;
>
> if (!dp_ctrl)
> return -EINVAL;
> @@ -1804,6 +1805,10 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
>
> ctrl->dp_ctrl.pixel_rate = ctrl->panel->dp_mode.drm_mode.clock;
>
> + pixel_rate_orig = ctrl->dp_ctrl.pixel_rate;
> + if (dp_ctrl->wide_bus_en)
> + ctrl->dp_ctrl.pixel_rate >>= 1;
> +
> DRM_DEBUG_DP("rate=%d, num_lanes=%d, pixel_rate=%d\n",
> ctrl->link->link_params.rate,
> ctrl->link->link_params.num_lanes, ctrl->dp_ctrl.pixel_rate);
> @@ -1839,11 +1844,11 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
> */
> reinit_completion(&ctrl->video_comp);
>
> - dp_ctrl_configure_source_params(ctrl);
> + dp_ctrl_configure_source_params(ctrl, dp_ctrl->wide_bus_en);
>
> dp_catalog_ctrl_config_msa(ctrl->catalog,
> ctrl->link->link_params.rate,
> - ctrl->dp_ctrl.pixel_rate, dp_ctrl_use_fixed_nvid(ctrl));
> + pixel_rate_orig, dp_ctrl_use_fixed_nvid(ctrl));
>
> dp_ctrl_setup_tr_unit(ctrl);
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
> index 2433edb..4dff44d 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
> @@ -17,6 +17,7 @@ struct dp_ctrl {
> bool orientation;
> atomic_t aborted;
> u32 pixel_rate;
> + bool wide_bus_en;
> };
>
> int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl);
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index e89556ad..d45a3aa 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -117,6 +117,8 @@ struct dp_display_private {
> struct dp_event event_list[DP_EVENT_Q_MAX];
> spinlock_t event_lock;
>
> + bool wide_bus_en;
> +
> struct dp_audio *audio;
> };
>
> @@ -845,6 +847,8 @@ static int dp_display_enable(struct dp_display_private *dp, u32 data)
> return 0;
> }
>
> + dp->ctrl->wide_bus_en = dp->wide_bus_en;
> +
> rc = dp_ctrl_on_stream(dp->ctrl);
> if (!rc)
> dp_display->power_on = true;
> @@ -979,6 +983,7 @@ int dp_display_get_modes(struct msm_dp *dp,
> dp->connector, dp_mode);
> if (dp_mode->drm_mode.clock)
> dp->max_pclk_khz = dp_mode->drm_mode.clock;
> +
> return ret;
> }
>
> @@ -1451,6 +1456,28 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display)
> }
> }
>
> +bool msm_dp_wide_bus_enable(struct msm_dp *dp_display)
> +{
> + struct dp_display_private *dp;
> + u32 revision, major, minor;
> +
> + dp = container_of(dp_display, struct dp_display_private, dp_display);
> +
> + /* for the time being widebus only support on DP */
> + if (dp_display->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {

Is there a reason for not enabling widebus for eDP? (I'm perfectly fine
with doing us doing that separately at a later point, but I'm curious)

> + revision = dp_catalog_hw_revision(dp->catalog);
> + major = ((revision >> 28) & 0x0ff);
> + minor = ((revision >> 16) & 0x0fff);
> +
> + DRM_DEBUG_DP("id=%d major=%d minor=%d\n", dp->id, major, minor);

The indentation of this line is wrong.

> +
> + if (major >= 1 && minor >= 2)
> + return true;
> + }
> +
> + return false;
> +}
> +
> void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
> {
> struct dp_display_private *dp;
> @@ -1505,6 +1532,9 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
> dp_priv->panel->connector = dp_display->connector;
>
> priv->connectors[priv->num_connectors++] = dp_display->connector;
> +
> + dp_priv->wide_bus_en = msm_dp_wide_bus_enable(dp_display);

Not sure if I'm missing some patches, but my branch branch doesn't have
a dp_priv in this function.

Regards,
Bjorn

> +
> return 0;
> }
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 8e80e3b..d9cb9ee 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -23,6 +23,8 @@ struct msm_dp {
>
> hdmi_codec_plugged_cb plugged_cb;
>
> + bool wide_bus_en;
> +
> u32 max_pclk_khz;
>
> u32 max_dp_lanes;
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
> index 71db10c..71deb1e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
> @@ -353,7 +353,7 @@ void dp_panel_dump_regs(struct dp_panel *dp_panel)
> dp_catalog_dump_regs(catalog);
> }
>
> -int dp_panel_timing_cfg(struct dp_panel *dp_panel)
> +int dp_panel_timing_cfg(struct dp_panel *dp_panel, bool wide_bus_en)
> {
> u32 data, total_ver, total_hor;
> struct dp_catalog *catalog;
> @@ -404,7 +404,7 @@ int dp_panel_timing_cfg(struct dp_panel *dp_panel)
>
> catalog->dp_active = data;
>
> - dp_catalog_panel_timing_cfg(catalog);
> + dp_catalog_panel_timing_cfg(catalog, wide_bus_en);
> panel->panel_on = true;
>
> return 0;
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
> index 9023e5b..5ec341a 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.h
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.h
> @@ -57,7 +57,7 @@ struct dp_panel {
>
> int dp_panel_init_panel_info(struct dp_panel *dp_panel);
> int dp_panel_deinit(struct dp_panel *dp_panel);
> -int dp_panel_timing_cfg(struct dp_panel *dp_panel);
> +int dp_panel_timing_cfg(struct dp_panel *dp_panel, bool wide_bus_en);
> void dp_panel_dump_regs(struct dp_panel *dp_panel);
> int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
> struct drm_connector *connector);
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index 07f6c41..667f3a8 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -398,6 +398,7 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display);
> void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp_display);
>
> void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor);
> +bool msm_dp_wide_bus_enable(struct msm_dp *dp_display);
>
> #else
> static inline int __init msm_dp_register(void)
> @@ -448,6 +449,11 @@ static inline void msm_dp_debugfs_init(struct msm_dp *dp_display,
> {
> }
>
> +bool msm_dp_wide_bus_enable(struct msm_dp *dp_display)
> +{
> + return false;
> +}
> +
> #endif
>
> void __init msm_mdp_register(void);
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

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In reply to: Kuogee Hsieh: "[PATCH v4 2/2] drm/msm/dp: enable widebus feature for display port"
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