Re: [PATCH 1/4] gpu: drm: replace of_graph_get_next_endpoint()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hello Morimoto-san,

Thank you for the patch.

On Tue, Feb 06, 2024 at 02:55:01AM +0000, Kuninori Morimoto wrote:
> From DT point of view, in general, drivers should be asking for a
> specific port number because their function is fixed in the binding.
> 
> of_graph_get_next_endpoint() doesn't match to this concept.
> 
> Simply replace
> 
> 	- of_graph_get_next_endpoint(xxx, NULL);
> 	+ of_graph_get_endpoint_by_regs(xxx, 0, -1);
> 
> Link: https://lore.kernel.org/r/20240202174941.GA310089-robh@kernel.org
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> ---
>  drivers/gpu/drm/drm_of.c                              | 2 +-
>  drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 2 +-
>  drivers/gpu/drm/tiny/arcpgu.c                         | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
> index 177b600895d3..c2eae9296012 100644
> --- a/drivers/gpu/drm/drm_of.c
> +++ b/drivers/gpu/drm/drm_of.c
> @@ -516,7 +516,7 @@ struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev)
>  	/*
>  	 * Get first endpoint child from device.
>  	 */
> -	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);

This assumes that the DSI device's port@0 will also be the input. That's
fine for current users of this function, but we should at least document
it.

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 177b600895d3..012c4d04cf51 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -504,6 +504,8 @@ EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);
  * Gets parent DSI bus for a DSI device controlled through a bus other
  * than MIPI-DCS (SPI, I2C, etc.) using the Device Tree.
  *
+ * This function assumes that the device's port@0 is the DSI input.
+ *
  * Returns pointer to mipi_dsi_host if successful, -EINVAL if the
  * request is unsupported, -EPROBE_DEFER if the DSI host is found but
  * not available, or -ENODEV otherwise.

With this,

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

>  	if (!endpoint)
>  		return ERR_PTR(-ENODEV);
>  
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> index 4618c892cdd6..e10e469aa7a6 100644
> --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -400,7 +400,7 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c)
>  	rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
>  
>  	/* Look up the DSI host.  It needs to probe before we do. */
> -	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
>  	if (!endpoint)
>  		return -ENODEV;
>  
> diff --git a/drivers/gpu/drm/tiny/arcpgu.c b/drivers/gpu/drm/tiny/arcpgu.c
> index e5b10e41554a..04d0053b9315 100644
> --- a/drivers/gpu/drm/tiny/arcpgu.c
> +++ b/drivers/gpu/drm/tiny/arcpgu.c
> @@ -288,7 +288,7 @@ static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
>  	 * There is only one output port inside each device. It is linked with
>  	 * encoder endpoint.
>  	 */
> -	endpoint_node = of_graph_get_next_endpoint(pdev->dev.of_node, NULL);
> +	endpoint_node = of_graph_get_endpoint_by_regs(pdev->dev.of_node, 0, -1);
>  	if (endpoint_node) {
>  		encoder_node = of_graph_get_remote_port_parent(endpoint_node);
>  		of_node_put(endpoint_node);

-- 
Regards,

Laurent Pinchart