Re: [PATCH v4 1/3] drm: add bus_formats and num_bus_formats fields to drm_display_info

[Thierry Reding <thierry.reding@gmail.com>]

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On Mon, Dec 01, 2014 at 09:20:59AM +0100, Boris Brezillon wrote:
> Add bus_formats and num_bus_formats fields and
> drm_display_info_set_bus_formats helper function to specify the bus
> formats supported by a given display.
> 
> This information can be used by display controller drivers to configure
> the output interface appropriately (i.e. RGB565, RGB666 or RGB888 on raw
> RGB or LVDS busses).
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
>  drivers/gpu/drm/drm_crtc.c | 32 ++++++++++++++++++++++++++++++++
>  include/drm/drm_crtc.h     |  7 +++++++
>  2 files changed, 39 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index e79c8d3..d3b7ed0 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -763,6 +763,38 @@ static void drm_mode_remove(struct drm_connector *connector,
>  	drm_mode_destroy(connector->dev, mode);
>  }
>  
> +/*

This needs a /** marker to make it a valid kerneldoc comment.

> + * drm_display_info_set_bus_formats - set the supported bus formats
> + * @info: display info to store bus formats in
> + * @fmts: array containing the supported bus formats
> + * @nfmts: the number of entries in the fmts array
> + *
> + * Store the suppported bus formats in display info structure.
> + * See MEDIA_BUS_FMT_* definitions in include/uapi/linux/media-bus-format.h for
> + * a full list of available formats.
> + */
> +int drm_display_info_set_bus_formats(struct drm_display_info *info, const u32 *fmts,

This one still exceeds 80-characters per line, but perhaps I'm reviewing
the wrong patch? Also I think fmts should be formats here.

> +				     unsigned int num_fmts)

And this should be num_formats, for consistency. Also make sure to keep
this consistent with the kerneldoc.

> +{
> +	u32 *formats = NULL;

If you name the parameter formats, maybe bus_formats would be a good
alternative for this local variable. Or fmts here. I think it's most
important that the public API gets the more idiomatic name.

> +
> +	if (!fmts && num_fmts)
> +		return -EINVAL;
> +
> +	if (fmts && num_fmts) {
> +		formats = kmemdup(fmts, sizeof(*fmts) * num_fmts, GFP_KERNEL);
> +		if (!formats)
> +			return -ENOMEM;
> +	}
> +
> +	kfree(info->bus_formats);
> +	info->bus_formats = formats;
> +	info->num_bus_formats = num_fmts;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_display_info_set_bus_formats);

I think you'll want to call kfree() on the bus_formats array from
drm_connector_cleanup() as well to make sure you don't leak this on
driver unload.

Thierry

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