linux-kernel - Re: [PATCH 39/45] drm/msm/dp: initialize dp

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Message-ID: <qu3b5cfxvxnnxwn4rwuqyxdpadrpvkhycyprs5n4aycecmdb4f@pvt2n3aajpxv>
Date: Sun, 8 Dec 2024 08:31:32 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Stephen Boyd <swboyd@...omium.org>, 
	Chandan Uddaraju <chandanu@...eaurora.org>, Guenter Roeck <groeck@...omium.org>, 
	Kuogee Hsieh <quic_khsieh@...cinc.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Vara Reddy <quic_varar@...cinc.com>, Rob Clark <robdclark@...omium.org>, 
	Tanmay Shah <tanmay@...eaurora.org>, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 39/45] drm/msm/dp: initialize dp_mst module for each DP
 MST controller

On Thu, Dec 05, 2024 at 08:32:10PM -0800, Abhinav Kumar wrote:
> For each MST capable DP controller, initialize a dp_mst module to
> manage its DP MST operations. The DP MST module for each controller
> is the central entity to manage its topology related operations as
> well as interfacing with the rest of the DP driver.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c |  6 ++++++
>  drivers/gpu/drm/msm/dp/dp_display.c     | 12 ++++++++++++
>  drivers/gpu/drm/msm/msm_drv.h           |  7 +++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 359de04abf4bbead3daa5e8b357a3c34216e3e65..734d8972bbd65153778d5d70a55ac09dfc693ac9 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -664,6 +664,12 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
>  		stream_cnt = msm_dp_get_mst_max_stream(priv->dp[i]);
>  
>  		if (stream_cnt > 1) {
> +			rc = msm_dp_mst_register(priv->dp[i]);
> +			if (rc) {
> +				DPU_ERROR("dp_mst_init failed for DP, rc = %d\n", rc);
> +				return rc;
> +			}
> +

This seems to be put backwards. I'd prefer if DPU driver allocated all
MST encoders and then called into the DP driver, letting it handle all
MST-related internals.

>  			for (stream_id = 0; stream_id < stream_cnt; stream_id++) {
>  				info.stream_id = stream_id;
>  				encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_DPMST, &info);
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index eafec9ab4f83cb44e861687e7550748b4d9b7ece..7f2eace17c126e3758c68bb0dee67662463a6e05 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -69,6 +69,8 @@ enum {
>  
>  #define WAIT_FOR_RESUME_TIMEOUT_JIFFIES (HZ / 2)
>  
> +#define MAX_DPCD_TRANSACTION_BYTES 16
> +
>  struct msm_dp_event {
>  	u32 event_id;
>  	u32 data;
> @@ -1689,6 +1691,16 @@ int msm_dp_modeset_init(struct msm_dp *msm_dp_display, struct drm_device *dev,
>  	return 0;
>  }
>  
> +int msm_dp_mst_register(struct msm_dp *dp)
> +{
> +	struct msm_dp_display_private *dp_display;
> +
> +	dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display);
> +
> +	return msm_dp_mst_init(dp, dp_display->max_stream,
> +			   MAX_DPCD_TRANSACTION_BYTES, dp_display->aux);

This doesn't seem to change between plaforms. Please push it to
msm_dp_mst_init() instead.

> +}
> +
>  void msm_dp_display_atomic_prepare(struct msm_dp *dp)
>  {
>  	int rc = 0;
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index 12b50a797772f574122481cd8a1c7c88aacb8250..7ed0e25d6c2bc9e4e3d78895742226d22d103e4c 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -376,6 +376,8 @@ int msm_dp_get_mst_max_stream(const struct msm_dp *dp_display);
>  
>  int msm_dp_mst_bridge_init(struct msm_dp *dp_display, struct drm_encoder *encoder);
>  
> +int msm_dp_mst_register(struct msm_dp *dp_display);
> +
>  #else
>  static inline int __init msm_dp_register(void)
>  {
> @@ -397,6 +399,11 @@ static inline int msm_dp_get_mst_max_stream(struct msm_dp *dp_display)
>  	return -EINVAL;
>  }
>  
> +static inline int msm_dp_mst_register(struct msm_dp *dp_display)
> +{
> +	return -EINVAL;
> +}
> +
>  int msm_dp_mst_bridge_init(struct msm_dp *dp_display, struct drm_encoder *encoder)
>  {
>  	return -EINVAL;
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry