Re: [PATCH v7 1/3] drm/bridge/synopsys: dsi: stop clobbering drvdata

[Philippe CORNU]

Hi Nickey,


On 12/12/2017 02:10 AM, Nickey Yang wrote:
> From: Brian Norris <briannorris@xxxxxxxxxxxx>
> 
> Bridge drivers/helpers shouldn't be clobbering the drvdata, since a
> parent driver might need to own this. Instead, let's return our
> 'dw_mipi_dsi' object and have callers pass that back to us for removal.
> 
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> Signed-off-by: Nickey Yang <nickey.yang@xxxxxxxxxxxxxx>
> Link:https://patchwork.kernel.org/patch/10078493/
> 
> ---
> Changes
> 
> v4:
> - Add From tag,update subject line
> - keep patch "drm/stm: dsi: Adjust dw_mipi_dsi_probe and remove"
>    in this piece together.
> 
> v5:
> - remove Review & Ack tag
> - fix remove() directly referencing the static
>    dw_mipi_dsi_stm_plat_data struct.
> 
> v7:
> - add missing platform_set_drvdata in stm part.
> 
>   drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 36 ++++++++++-----------------
>   drivers/gpu/drm/stm/dw_mipi_dsi-stm.c         | 12 ++++++---
>   include/drm/bridge/dw_mipi_dsi.h              | 17 ++++++++-----
>   3 files changed, 32 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> index d9cca4f..c39c7dc 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -922,8 +922,6 @@ static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge)
>   	dsi->bridge.of_node = pdev->dev.of_node;
>   #endif
>   
> -	dev_set_drvdata(dev, dsi);
> -
>   	return dsi;
>   }
>   
> @@ -935,23 +933,16 @@ static void __dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
>   /*
>    * Probe/remove API, used from platforms based on the DRM bridge API.
>    */
> -int dw_mipi_dsi_probe(struct platform_device *pdev,
> -		      const struct dw_mipi_dsi_plat_data *plat_data)
> +struct dw_mipi_dsi *
> +dw_mipi_dsi_probe(struct platform_device *pdev,
> +		  const struct dw_mipi_dsi_plat_data *plat_data)
>   {
> -	struct dw_mipi_dsi *dsi;
> -
> -	dsi = __dw_mipi_dsi_probe(pdev, plat_data);
> -	if (IS_ERR(dsi))
> -		return PTR_ERR(dsi);
> -
> -	return 0;
> +	return __dw_mipi_dsi_probe(pdev, plat_data);
>   }
>   EXPORT_SYMBOL_GPL(dw_mipi_dsi_probe);
>   
> -void dw_mipi_dsi_remove(struct platform_device *pdev)
> +void dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
>   {
> -	struct dw_mipi_dsi *dsi = platform_get_drvdata(pdev);
> -
>   	mipi_dsi_host_unregister(&dsi->dsi_host);
>   
>   	__dw_mipi_dsi_remove(dsi);
> @@ -961,31 +952,30 @@ void dw_mipi_dsi_remove(struct platform_device *pdev)
>   /*
>    * Bind/unbind API, used from platforms based on the component framework.
>    */
> -int dw_mipi_dsi_bind(struct platform_device *pdev, struct drm_encoder *encoder,
> -		     const struct dw_mipi_dsi_plat_data *plat_data)
> +struct dw_mipi_dsi *
> +dw_mipi_dsi_bind(struct platform_device *pdev, struct drm_encoder *encoder,
> +		 const struct dw_mipi_dsi_plat_data *plat_data)
>   {
>   	struct dw_mipi_dsi *dsi;
>   	int ret;
>   
>   	dsi = __dw_mipi_dsi_probe(pdev, plat_data);
>   	if (IS_ERR(dsi))
> -		return PTR_ERR(dsi);
> +		return dsi;
>   
>   	ret = drm_bridge_attach(encoder, &dsi->bridge, NULL);
>   	if (ret) {
> -		dw_mipi_dsi_remove(pdev);
> +		dw_mipi_dsi_remove(dsi);
>   		DRM_ERROR("Failed to initialize bridge with drm\n");
> -		return ret;
> +		return ERR_PTR(ret);
>   	}
>   
> -	return 0;
> +	return dsi;
>   }
>   EXPORT_SYMBOL_GPL(dw_mipi_dsi_bind);
>   
> -void dw_mipi_dsi_unbind(struct device *dev)
> +void dw_mipi_dsi_unbind(struct dw_mipi_dsi *dsi)
>   {
> -	struct dw_mipi_dsi *dsi = dev_get_drvdata(dev);
> -
>   	__dw_mipi_dsi_remove(dsi);
>   }
>   EXPORT_SYMBOL_GPL(dw_mipi_dsi_unbind);
> diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> index e5b6310..c1ed691 100644
> --- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> +++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> @@ -66,6 +66,7 @@ enum dsi_color {
>   struct dw_mipi_dsi_stm {
>   	void __iomem *base;
>   	struct clk *pllref_clk;
> +	struct dw_mipi_dsi *dmd;
>   };
>   
>   static inline void dsi_write(struct dw_mipi_dsi_stm *dsi, u32 reg, u32 val)
> @@ -290,6 +291,8 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>   	if (!dsi)
>   		return -ENOMEM;
>   
> +	platform_set_drvdata(pdev, dsi);
> +

Why don't you simply use the original patch from Brian.
With your last update, platform_set_drvdata() is called early during the 
stm_probe() and this is not the "classic" way: most of the time we 
prefer calling platform_set_drvdata() at the end of the probe (or as 
close as possible of the end of the probe). I took few minutes to look 
into drm directory and it seems to be the classic way for most of the 
drivers...

>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>   	if (!res) {
>   		DRM_ERROR("Unable to get resource\n");
> @@ -318,10 +321,11 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>   	dw_mipi_dsi_stm_plat_data.base = dsi->base;
>   	dw_mipi_dsi_stm_plat_data.priv_data = dsi;
>   
> -	ret = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data);
> -	if (ret) {
> +	dsi->dmd = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data);
> +	if (IS_ERR(dsi->dmd)) {
>   		DRM_ERROR("Failed to initialize mipi dsi host\n");
>   		clk_disable_unprepare(dsi->pllref_clk);
> +		return PTR_ERR(dsi->dmd);
>   	}
>   
>   	return ret;

Moreover, I do prefer the "return 0;" from the Brian original version 
because "ret" here is far from its usage (from clk_prepare_enable()) 
with this new patch.

So, once again, I really prefer the Brian original version, on which you 
already got my Tested-By & Acked-by.

Is there any reason why you did not use the original patch?

Many thanks,
Philippe :-)
Note: I will be ooo next 2 weeks.

> @@ -329,10 +333,10 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>   
>   static int dw_mipi_dsi_stm_remove(struct platform_device *pdev)
>   {
> -	struct dw_mipi_dsi_stm *dsi = dw_mipi_dsi_stm_plat_data.priv_data;
> +	struct dw_mipi_dsi_stm *dsi = platform_get_drvdata(pdev);
>   
>   	clk_disable_unprepare(dsi->pllref_clk);
> -	dw_mipi_dsi_remove(pdev);
> +	dw_mipi_dsi_remove(dsi->dmd);
>   
>   	return 0;
>   }
> diff --git a/include/drm/bridge/dw_mipi_dsi.h b/include/drm/bridge/dw_mipi_dsi.h
> index 9b30fec..d9c6d54 100644
> --- a/include/drm/bridge/dw_mipi_dsi.h
> +++ b/include/drm/bridge/dw_mipi_dsi.h
> @@ -10,6 +10,8 @@
>   #ifndef __DW_MIPI_DSI__
>   #define __DW_MIPI_DSI__
>   
> +struct dw_mipi_dsi;
> +
>   struct dw_mipi_dsi_phy_ops {
>   	int (*init)(void *priv_data);
>   	int (*get_lane_mbps)(void *priv_data, struct drm_display_mode *mode,
> @@ -29,11 +31,14 @@ struct dw_mipi_dsi_plat_data {
>   	void *priv_data;
>   };
>   
> -int dw_mipi_dsi_probe(struct platform_device *pdev,
> -		      const struct dw_mipi_dsi_plat_data *plat_data);
> -void dw_mipi_dsi_remove(struct platform_device *pdev);
> -int dw_mipi_dsi_bind(struct platform_device *pdev, struct drm_encoder *encoder,
> -		     const struct dw_mipi_dsi_plat_data *plat_data);
> -void dw_mipi_dsi_unbind(struct device *dev);
> +struct dw_mipi_dsi *dw_mipi_dsi_probe(struct platform_device *pdev,
> +				      const struct dw_mipi_dsi_plat_data
> +				      *plat_data);
> +void dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi);
> +struct dw_mipi_dsi *dw_mipi_dsi_bind(struct platform_device *pdev,
> +				     struct drm_encoder *encoder,
> +				     const struct dw_mipi_dsi_plat_data
> +				     *plat_data);
> +void dw_mipi_dsi_unbind(struct dw_mipi_dsi *dsi);
>   
>   #endif /* __DW_MIPI_DSI__ */
>