Re: [PATCH v5 04/15] drm/msm/dp: split msm_dp_ctrl_config_ctrl() into link parts and stream parts

[Dmitry Baryshkov]

On Thu, May 28, 2026 at 06:40:25PM +0800, Yongxing Mou wrote:
> The DP_CONFIGURATION_CTRL register contains both link-level and
> stream-specific fields. Currently, msm_dp_ctrl_config_ctrl() configures
> all of them together. Separate the configuration into link parts and
> stream parts to support MST.
> 
> Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c | 47 +++++++++++++++++++++++++++-------------
>  1 file changed, 32 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 86ef8c89ad44..cc00e8d2d6c7 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -388,26 +388,45 @@ void msm_dp_ctrl_push_idle(struct msm_dp_ctrl *msm_dp_ctrl)
>  	drm_dbg_dp(ctrl->drm_dev, "mainlink off\n");
>  }
>  
> -static void msm_dp_ctrl_config_ctrl(struct msm_dp_ctrl_private *ctrl)
> +static void msm_dp_ctrl_config_ctrl_streams(struct msm_dp_ctrl_private *ctrl,
> +					    struct msm_dp_panel *msm_dp_panel)
>  {
>  	u32 config = 0, tbd;
> +
> +	/*
> +	 * RMW: in SST, config_ctrl_link and config_ctrl_streams are called
> +	 * sequentially on the same thread. In MST, caller holds mst_lock.

There is neither MST nor mst_lock. Also being called on the same thread
means nothing, there can be another thread, executing the same code
concurretly. Please point out that they are called only from the
atomic_enable() callback, which is guarantted to be executed once at a
time.

> +	 */
> +	config = msm_dp_read_link(ctrl, REG_DP_CONFIGURATION_CTRL);

-- 
With best wishes
Dmitry