Re: [PATCH 19/32] drm: Store a pointer to drm_format_info under drm_framebuffer

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

Hi Ville,

Thank you for the patch.

On Thursday 17 Nov 2016 18:14:18 ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> To avoid having to look up the format information struct every time,
> let's just store a pointer to it under drm_framebuffer.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_framebuffer.c    | 4 +++-
>  drivers/gpu/drm/drm_modeset_helper.c | 1 +
>  include/drm/drm_framebuffer.h        | 4 ++++
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_framebuffer.c
> b/drivers/gpu/drm/drm_framebuffer.c index 527220c08f9b..47478678d609 100644
> --- a/drivers/gpu/drm/drm_framebuffer.c
> +++ b/drivers/gpu/drm/drm_framebuffer.c
> @@ -632,8 +632,10 @@ int drm_framebuffer_init(struct drm_device *dev, struct
> drm_framebuffer *fb, int ret;
> 
>  	INIT_LIST_HEAD(&fb->filp_head);
> -	if (WARN_ON_ONCE(fb->dev != dev))
> +	if (WARN_ON_ONCE(fb->dev != dev)) {
>  		fb->dev = dev;
> +		fb->format = drm_format_info(fb->pixel_format);
> +	}


With this drivers will start relying on fb->format. I believe we should commit 
to provide a non-NULL format info to avoid having to sprinkle NULL checks in 
all drivers. Should drm_framebuffer_init() return an error in that case ? Or 
do we guarantee already through another mean that the pixel format is valid 
and will always lead to a non-NULL format info here ?

>  	fb->funcs = funcs;
> 
>  	ret = drm_mode_object_get_reg(dev, &fb->base, DRM_MODE_OBJECT_FB,
> diff --git a/drivers/gpu/drm/drm_modeset_helper.c
> b/drivers/gpu/drm/drm_modeset_helper.c index 57a319e3f780..1aa5e3bcc8a1
> 100644
> --- a/drivers/gpu/drm/drm_modeset_helper.c
> +++ b/drivers/gpu/drm/drm_modeset_helper.c
> @@ -91,6 +91,7 @@ void drm_helper_mode_fill_fb_struct(struct drm_device
> *dev, }
> 
>  	fb->dev = dev;
> +	fb->format = info;
>  	fb->width = mode_cmd->width;
>  	fb->height = mode_cmd->height;
>  	for (i = 0; i < 4; i++) {
> diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h
> index b3141a0e609b..741b3a994d1f 100644
> --- a/include/drm/drm_framebuffer.h
> +++ b/include/drm/drm_framebuffer.h
> @@ -122,6 +122,10 @@ struct drm_framebuffer {
>  	 */
>  	struct drm_mode_object base;
>  	/**
> +	 * @format: framebuffer format information
> +	 */
> +	const struct drm_format_info *format;
> +	/**
>  	 * @funcs: framebuffer vfunc table
>  	 */
>  	const struct drm_framebuffer_funcs *funcs;

-- 
Regards,

Laurent Pinchart

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