Re: [PATCH 1/2] drm/edid: split VIC display mode lookup into a separate function

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Nov 28, 2013 at 05:12:46PM +0000, Thomas Wood wrote:
> Signed-off-by: Thomas Wood <thomas.wood@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 67 +++++++++++++++++++++++++++-------------------
>  1 file changed, 39 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 52e060e..1dd82cd 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2557,25 +2557,40 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
>  	return modes;
>  }
>  
> -static int
> -do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> +static struct drm_display_mode *
> +drm_display_mode_from_vic_index(struct drm_connector *connector,
> +				const u8 *video_db, u8 video_len,
> +				u8 video_index)
>  {
>  	struct drm_device *dev = connector->dev;
> -	const u8 *mode;
> +	struct drm_display_mode *newmode;
>  	u8 cea_mode;
> -	int modes = 0;
>  
> -	for (mode = db; mode < db + len; mode++) {
> -		cea_mode = (*mode & 127) - 1; /* CEA modes are numbered 1..127 */
> -		if (cea_mode < ARRAY_SIZE(edid_cea_modes)) {
> -			struct drm_display_mode *newmode;
> -			newmode = drm_mode_duplicate(dev,
> -						     &edid_cea_modes[cea_mode]);
> -			if (newmode) {
> -				newmode->vrefresh = 0;
> -				drm_mode_probed_add(connector, newmode);
> -				modes++;
> -			}
> +	if (video_db == NULL || video_index > video_len)
> +		return NULL;

Hmm, this seems wrong. video_len is the length of the payload only,
so the check should be >=. But this bug is already present in
the current code in add_3d_struct_modes(). So maybe include another
patch to fix that up first.

The rest looks OK to me.

> +
> +	/* CEA modes are numbered 1..127 */
> +	cea_mode = (video_db[video_index] & 127) - 1;
> +	if (cea_mode >= ARRAY_SIZE(edid_cea_modes))
> +		return NULL;
> +
> +	newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
> +	newmode->vrefresh = 0;
> +
> +	return newmode;
> +}
> +
> +static int
> +do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> +{
> +	int i, modes = 0;
> +
> +	for (i = 0; i < len; i++) {
> +		struct drm_display_mode *mode;
> +		mode = drm_display_mode_from_vic_index(connector, db, len, i);
> +		if (mode) {
> +			drm_mode_probed_add(connector, mode);
> +			modes++;
>  		}
>  	}
>  
> @@ -2669,21 +2684,13 @@ static int add_hdmi_mode(struct drm_connector *connector, u8 vic)
>  static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
>  			       const u8 *video_db, u8 video_len, u8 video_index)
>  {
> -	struct drm_device *dev = connector->dev;
>  	struct drm_display_mode *newmode;
>  	int modes = 0;
> -	u8 cea_mode;
> -
> -	if (video_db == NULL || video_index > video_len)
> -		return 0;
> -
> -	/* CEA modes are numbered 1..127 */
> -	cea_mode = (video_db[video_index] & 127) - 1;
> -	if (cea_mode >= ARRAY_SIZE(edid_cea_modes))
> -		return 0;
>  
>  	if (structure & (1 << 0)) {
> -		newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
> +		newmode = drm_display_mode_from_vic_index(connector, video_db,
> +							  video_len,
> +							  video_index);
>  		if (newmode) {
>  			newmode->flags |= DRM_MODE_FLAG_3D_FRAME_PACKING;
>  			drm_mode_probed_add(connector, newmode);
> @@ -2691,7 +2698,9 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
>  		}
>  	}
>  	if (structure & (1 << 6)) {
> -		newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
> +		newmode = drm_display_mode_from_vic_index(connector, video_db,
> +							  video_len,
> +							  video_index);
>  		if (newmode) {
>  			newmode->flags |= DRM_MODE_FLAG_3D_TOP_AND_BOTTOM;
>  			drm_mode_probed_add(connector, newmode);
> @@ -2699,7 +2708,9 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
>  		}
>  	}
>  	if (structure & (1 << 8)) {
> -		newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
> +		newmode = drm_display_mode_from_vic_index(connector, video_db,
> +							  video_len,
> +							  video_index);
>  		if (newmode) {
>  			newmode->flags |= DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF;
>  			drm_mode_probed_add(connector, newmode);
> -- 
> 1.8.4.2
> 
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-- 
Ville Syrjälä
Intel OTC