Re: [PATCH v4 13/39] drm/msm/dp: introduce stream_id for each DP panel

Dmitry Baryshkov
2026-04-11T17:56:00Z

On Fri, Apr 10, 2026 at 05:33:48PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@quicinc.com>
>
> With MST, each DP controller can handle multiple streams.
> There shall be one dp_panel for each stream but the dp_display
> object shall be shared among them. To represent this abstraction,
> create a stream_id for each DP panel which shall be set by the
> MST stream. For SST, default this to stream 0.
>
> Use the stream ID to control the pixel clock of that respective
> stream by extending the clock handles and state tracking of the
> DP pixel clock to an array of max supported streams. The maximum
> streams currently is 4.

Please mention that panels are going to be dynamically assigned to
actual stream IDs.

>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
> ---
> drivers/gpu/drm/msm/dp/dp_ctrl.c | 57 +++++++++++++++++++++++--------------
> drivers/gpu/drm/msm/dp/dp_ctrl.h | 2 +-
> drivers/gpu/drm/msm/dp/dp_display.c | 24 ++++++++++++++--
> drivers/gpu/drm/msm/dp/dp_display.h | 2 ++
> drivers/gpu/drm/msm/dp/dp_panel.h | 11 +++++++
> 5 files changed, 71 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 120ec00884e5..fb6396727628 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -127,7 +127,7 @@ struct msm_dp_ctrl_private {
> unsigned int num_link_clks;
> struct clk_bulk_data *link_clks;
>
> - struct clk *pixel_clk;
> + struct clk *pixel_clk[DP_STREAM_MAX];
>
> union phy_configure_opts phy_opts;
>
> @@ -139,7 +139,7 @@ struct msm_dp_ctrl_private {
>
> bool core_clks_on;
> bool link_clks_on;
> - bool stream_clks_on;
> + bool stream_clks_on[DP_STREAM_MAX];
> };
>
> static inline u32 msm_dp_read_ahb(const struct msm_dp_ctrl_private *ctrl, u32 offset)
> @@ -2176,39 +2176,40 @@ static bool msm_dp_ctrl_send_phy_test_pattern(struct msm_dp_ctrl_private *ctrl)
> return success;
> }
>
> -static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate)
> +static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate,
> + enum msm_dp_stream_id stream_id)
> {
> int ret;
>
> - ret = clk_set_rate(ctrl->pixel_clk, pixel_rate * 1000);
> + ret = clk_set_rate(ctrl->pixel_clk[stream_id], pixel_rate * 1000);
> if (ret) {
> DRM_ERROR("Failed to set pixel clock rate. ret=%d\n", ret);
> return ret;
> }
>
> - if (ctrl->stream_clks_on) {
> + if (ctrl->stream_clks_on[stream_id]) {
> drm_dbg_dp(ctrl->drm_dev, "pixel clks already enabled\n");
> } else {
> - ret = clk_prepare_enable(ctrl->pixel_clk);
> + ret = clk_prepare_enable(ctrl->pixel_clk[stream_id]);
> if (ret) {
> DRM_ERROR("Failed to start pixel clocks. ret=%d\n", ret);
> return ret;
> }
> - ctrl->stream_clks_on = true;
> + ctrl->stream_clks_on[stream_id] = true;
> }
>
> return ret;
> }
>
> -void msm_dp_ctrl_off_pixel_clk(struct msm_dp_ctrl *msm_dp_ctrl)
> +void msm_dp_ctrl_off_pixel_clk(struct msm_dp_ctrl *msm_dp_ctrl, enum msm_dp_stream_id stream_id)
> {
> struct msm_dp_ctrl_private *ctrl;
>
> ctrl = container_of(msm_dp_ctrl, struct msm_dp_ctrl_private, msm_dp_ctrl);
>
> - if (ctrl->stream_clks_on) {
> - clk_disable_unprepare(ctrl->pixel_clk);
> - ctrl->stream_clks_on = false;
> + if (ctrl->stream_clks_on[stream_id]) {
> + clk_disable_unprepare(ctrl->pixel_clk[stream_id]);
> + ctrl->stream_clks_on[stream_id] = false;
> }
> }
>
> @@ -2228,7 +2229,7 @@ static int msm_dp_ctrl_process_phy_test_request(struct msm_dp_ctrl_private *ctrl
> * running. Add the global reset just before disabling the
> * link clocks and core clocks.
> */
> - msm_dp_ctrl_off_pixel_clk(&ctrl->msm_dp_ctrl);
> + msm_dp_ctrl_off_pixel_clk(&ctrl->msm_dp_ctrl, ctrl->panel->stream_id);

Why are we using ctrl->panel again here for the stream-related
functions? Didn't you got rid of its usage few patches ago?

> msm_dp_ctrl_off_link(&ctrl->msm_dp_ctrl);
>
> ret = msm_dp_ctrl_on_link(&ctrl->msm_dp_ctrl);
> @@ -2238,7 +2239,7 @@ static int msm_dp_ctrl_process_phy_test_request(struct msm_dp_ctrl_private *ctrl
> }
>
> pixel_rate = ctrl->panel->msm_dp_mode.drm_mode.clock;
> - ret = msm_dp_ctrl_on_pixel_clk(ctrl, pixel_rate);
> + ret = msm_dp_ctrl_on_pixel_clk(ctrl, pixel_rate, ctrl->panel->stream_id);

And here...

>
> msm_dp_ctrl_send_phy_test_pattern(ctrl);
>
> @@ -1451,6 +1469,8 @@ void msm_dp_display_atomic_enable(struct msm_dp *msm_dp_display)
>
> dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>
> + msm_dp_display_set_stream_info(msm_dp_display, dp->panel, 0);

DP_STREAM_0

> +
> rc = msm_dp_display_enable(dp);
> if (rc)
> DRM_ERROR("DP display enable failed, rc=%d\n", rc);

--
With best wishes
Dmitry