Re: [PATCH 3/8] media: v4l: fwnode: Support acpi devices for v4l2_fwnode_device_parse

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Ricardo,

Thanks for the patch.

On Thu, Apr 03, 2025 at 07:16:14PM +0000, Ricardo Ribalda wrote:
> This patch modifies v4l2_fwnode_device_parse() to support ACPI devices.
> 
> We initially add support only for orientation via the ACPI _PLD method.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/v4l2-core/v4l2-fwnode.c | 58 +++++++++++++++++++++++++++++++----
>  1 file changed, 52 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> index cb153ce42c45d69600a3ec4e59a5584d7e791a2a..81563c36b6436bb61e1c96f2a5ede3fa9d64dab3 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -15,6 +15,7 @@
>   * Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
>   */
>  #include <linux/acpi.h>
> +#include <acpi/acpi_bus.h>
>  #include <linux/kernel.h>
>  #include <linux/mm.h>
>  #include <linux/module.h>
> @@ -807,16 +808,47 @@ int v4l2_fwnode_connector_add_link(struct fwnode_handle *fwnode,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_connector_add_link);
>  
> -int v4l2_fwnode_device_parse(struct device *dev,
> -			     struct v4l2_fwnode_device_properties *props)
> +static int v4l2_fwnode_device_parse_acpi(struct device *dev,
> +					 struct v4l2_fwnode_device_properties *props)
> +{
> +	struct acpi_pld_info *pld;
> +	int ret = 0;
> +
> +	if (!acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld)) {
> +		dev_dbg(dev, "acpi _PLD call failed\n");
> +		return 0;
> +	}

You could have software nodes in an ACPI system as well as DT-aligned
properties. They're not the primary means to convey this information still.

How about returning e.g. -ENODATA here if _PLD doesn't exist for the device
and then proceeding to parse properties as in DT?

> +
> +	switch (pld->panel) {
> +	case ACPI_PLD_PANEL_FRONT:
> +		props->orientation = V4L2_FWNODE_ORIENTATION_FRONT;
> +		break;
> +	case ACPI_PLD_PANEL_BACK:
> +		props->orientation = V4L2_FWNODE_ORIENTATION_BACK;
> +		break;
> +	case ACPI_PLD_PANEL_TOP:
> +	case ACPI_PLD_PANEL_LEFT:
> +	case ACPI_PLD_PANEL_RIGHT:
> +	case ACPI_PLD_PANEL_UNKNOWN:
> +		props->orientation = V4L2_FWNODE_ORIENTATION_EXTERNAL;
> +		break;

How about the rotation in _PLD?

> +	default:
> +		dev_dbg(dev, "Unknown _PLD panel val %d\n", pld->panel);
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	ACPI_FREE(pld);
> +	return ret;
> +}
> +
> +static int v4l2_fwnode_device_parse_dt(struct device *dev,
> +				       struct v4l2_fwnode_device_properties *props)
>  {
>  	struct fwnode_handle *fwnode = dev_fwnode(dev);
>  	u32 val;
>  	int ret;
>  
> -	memset(props, 0, sizeof(*props));
> -
> -	props->orientation = V4L2_FWNODE_PROPERTY_UNSET;
>  	ret = fwnode_property_read_u32(fwnode, "orientation", &val);
>  	if (!ret) {
>  		switch (val) {
> @@ -833,7 +865,6 @@ int v4l2_fwnode_device_parse(struct device *dev,
>  		dev_dbg(dev, "device orientation: %u\n", val);
>  	}
>  
> -	props->rotation = V4L2_FWNODE_PROPERTY_UNSET;
>  	ret = fwnode_property_read_u32(fwnode, "rotation", &val);
>  	if (!ret) {
>  		if (val >= 360) {
> @@ -847,6 +878,21 @@ int v4l2_fwnode_device_parse(struct device *dev,
>  
>  	return 0;
>  }
> +
> +int v4l2_fwnode_device_parse(struct device *dev,
> +			     struct v4l2_fwnode_device_properties *props)
> +{
> +	struct fwnode_handle *fwnode = dev_fwnode(dev);
> +
> +	memset(props, 0, sizeof(*props));
> +
> +	props->orientation = V4L2_FWNODE_PROPERTY_UNSET;
> +	props->rotation = V4L2_FWNODE_PROPERTY_UNSET;
> +
> +	if (is_acpi_device_node(fwnode))
> +		return v4l2_fwnode_device_parse_acpi(dev, props);
> +	return v4l2_fwnode_device_parse_dt(dev, props);
> +}
>  EXPORT_SYMBOL_GPL(v4l2_fwnode_device_parse);
>  
>  /*
> 

-- 
Kind regards,

Sakari Ailus