Re: [PATCH 1/5] drm/msm/dsi: move bonded command failure flag into dsi manager state

[Dmitry Baryshkov]

On Sat, Oct 31, 2026 at 11:03:01PM +0800, Qianhui Xu wrote:
> The bonded-DSI command path kept a file-scoped `static bool
> dsi_bonded_cmd_failed` next to the global manager instance, so bonded
> state was split across two storage classes. Move the flag into
> struct msm_dsi_manager (msm_dsim_glb) so the manager owns all of it and
> nothing mutable stays file-scoped. READ_ONCE/WRITE_ONCE use is unchanged,
> so behaviour is identical.
> 
> Signed-off-by: Qianhui Xu <xiaqinghuan@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/dsi/dsi_manager.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> index 559c07a8b9..93d636220b 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
> @@ -30,6 +30,7 @@ struct msm_dsi_manager {
>  	bool is_bonded_dsi;
>  	bool is_sync_needed;
>  	bool is_sm8750;
> +	bool bonded_cmd_failed;
>  	int master_dsi_link_id;
>  };
>  
> @@ -37,8 +38,10 @@ static struct msm_dsi_manager msm_dsim_glb = {
>  	.master_dsi_link_id = -1,
>  };
>  
> +/* Serialises bonded command transactions; the failure flag it guards lives in
> + * msm_dsim_glb so no bonded state is file-scoped.
> + */

If all fields guarded by this lock are held in another place, then the
lock should also go. Nit: please check the recommended form for the
block comment.

>  static DEFINE_MUTEX(dsi_bonded_cmd_lock);

Hmm what is your base kernel? I don't see these definitions.

> -static bool dsi_bonded_cmd_failed;
>  
>  #define IS_BONDED_DSI()		(msm_dsim_glb.is_bonded_dsi)
>  #define IS_SYNC_NEEDED()	(msm_dsim_glb.is_sync_needed)
> @@ -51,7 +54,8 @@ static bool dsi_mgr_uses_bonded_cmd(void)
>  
>  bool msm_dsi_manager_cmd_failed(void)
>  {
> -	return dsi_mgr_uses_bonded_cmd() && READ_ONCE(dsi_bonded_cmd_failed);
> +	return dsi_mgr_uses_bonded_cmd() &&
> +	       READ_ONCE(msm_dsim_glb.bonded_cmd_failed);
>  }
>  
>  static inline struct msm_dsi *dsi_mgr_get_dsi(int id)
> @@ -374,7 +378,7 @@ static void dsi_mgr_bridge_enable(struct drm_bridge *bridge,
>  	if (!panel->prepared) {
>  		dev_err(&msm_dsi->pdev->dev,
>  			"panel is not prepared; refusing video enable\n");
> -		WRITE_ONCE(dsi_bonded_cmd_failed, true);
> +		WRITE_ONCE(msm_dsim_glb.bonded_cmd_failed, true);
>  		return;
>  	}
>  
> @@ -646,7 +650,7 @@ static int dsi_mgr_bonded_cmd_xfer(const struct mipi_dsi_msg *msg)
>  	ret = master_ret < 0 ? master_ret : slave_ret < 0 ? slave_ret : len;
>  	if (ret < 0) {
>  		/* Never reuse a packet buffer while either DMA engine is unresolved. */
> -		WRITE_ONCE(dsi_bonded_cmd_failed, true);
> +		WRITE_ONCE(msm_dsim_glb.bonded_cmd_failed, true);
>  		dev_err(&master_dsi->pdev->dev,
>  			"bonded command DMA failed: master=%d peer=%d\n",
>  			master_ret, slave_ret);
> -- 
> 2.53.0
> 

-- 
With best wishes
Dmitry