Re: [PATCH v7 08/35] drm/msm/dp: add support to send ACT packets for MST

[Dmitry Baryshkov]

On Tue, Sep 29, 2026 at 12:25:32PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> 
> Whenever virtual channel slot allocation changes, the DP
> source must send the action control trigger sequence to notify
> the sink about the same. This would be applicable during the
> start and stop of the pixel stream. Add the infrastructure
> to be able to send ACT packets for the DP controller when
> operating in MST mode.
> 
> Add REG_DP_MST_ACT, the ACT trigger register used by this sequence.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    | 44 ++++++++++++++++++++++++++++++++++++-
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |  5 ++++-
>  drivers/gpu/drm/msm/dp/dp_display.c |  3 ++-
>  drivers/gpu/drm/msm/dp/dp_display.h |  1 +
>  drivers/gpu/drm/msm/dp/dp_reg.h     |  1 +
>  5 files changed, 51 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index e1614bc49a7c..65d22505c2b6 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -142,6 +142,7 @@ struct msm_dp_ctrl_private {
>  	bool core_clks_on;
>  	bool link_clks_on;
>  	bool stream_clks_on[DP_STREAM_MAX];
> +	bool mst_active;

I really don't like the idea of having this flag in two locations. Here
and in the msm_dp_display_private. Can we have it in one place only?

>  };
>  

[...]

>  
>  static void msm_dp_display_unprepare(struct msm_dp_display_private *dp)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 83117e7619f3..472429d09200 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -19,6 +19,7 @@ struct msm_dp {
>  	struct drm_bridge *bridge;
>  	bool audio_enabled;
>  	bool power_on;
> +	bool mst_active;
>  	unsigned int connector_type;
>  	bool is_edp;
>  

-- 
With best wishes
Dmitry