Re: [PATCH v4 35/39] drm/msm/dp: wire MST helpers into atomic check and commit paths

[Dmitry Baryshkov]

On Fri, Apr 10, 2026 at 05:34:10PM +0800, Yongxing Mou wrote:
> Call drm_dp_mst_atomic_check() from msm_atomic_check() so MST-specific
> state, such as connector and topology changes, is validated as part of
> the atomic check.
> 
> Hook the MST helpers into atomic_commit_setup() and
> atomic_commit_tail() to support non-blocking atomic commits for
> DisplayPort MST, and ensure MST commits properly wait for dependencies.
> 
> For SST, non-blocking commits are already handled via commit_tail(),
> which waits for dependencies in the DRM core.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/msm_atomic.c | 9 ++++++++-
>  drivers/gpu/drm/msm/msm_kms.c    | 2 ++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
> index 87a91148a731..ea064aa6d8fc 100644
> --- a/drivers/gpu/drm/msm/msm_atomic.c
> +++ b/drivers/gpu/drm/msm/msm_atomic.c
> @@ -4,6 +4,7 @@
>   * Author: Rob Clark <robdclark@xxxxxxxxx>
>   */
>  
> +#include <drm/display/drm_dp_mst_helper.h>
>  #include <drm/drm_atomic_uapi.h>
>  #include <drm/drm_vblank.h>
>  
> @@ -207,7 +208,11 @@ int msm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
>  	if (ret)
>  		return ret;
>  
> -	return drm_atomic_helper_check(dev, state);
> +	ret = drm_atomic_helper_check(dev, state);
> +	if (ret)
> +		return ret;
> +
> +	return drm_dp_mst_atomic_check(state);
>  }
>  
>  void msm_atomic_commit_tail(struct drm_atomic_state *state)
> @@ -221,6 +226,8 @@ void msm_atomic_commit_tail(struct drm_atomic_state *state)
>  
>  	trace_msm_atomic_commit_tail_start(async, crtc_mask);
>  
> +	drm_dp_mst_atomic_wait_for_dependencies(state);
> +
>  	kms->funcs->enable_commit(kms);
>  
>  	/*
> diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
> index e5d0ea629448..a8f5fbb3239d 100644
> --- a/drivers/gpu/drm/msm/msm_kms.c
> +++ b/drivers/gpu/drm/msm/msm_kms.c
> @@ -10,6 +10,7 @@
>  #include <linux/sched/mm.h>
>  #include <uapi/linux/sched/types.h>
>  
> +#include <drm/display/drm_dp_mst_helper.h>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_mode_config.h>
>  #include <drm/drm_vblank.h>
> @@ -29,6 +30,7 @@ static const struct drm_mode_config_funcs mode_config_funcs = {
>  
>  static const struct drm_mode_config_helper_funcs mode_config_helper_funcs = {
>  	.atomic_commit_tail = msm_atomic_commit_tail,
> +	.atomic_commit_setup = drm_dp_mst_atomic_setup_commit,

I usually hate one-liners, but here I'd prefer to see this call as a
part of the msm_atomic.c

>  };
>  
>  static irqreturn_t msm_irq(int irq, void *arg)
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry