[RFC PATCH] drm/edid: index CEA/HDMI mode tables using the VIC

[Ville Syrjälä]

On Tue, Dec 01, 2015 at 05:16:54PM +0200, Jani Nikula wrote:
> Add a dummy entry to CEA/HDMI mode tables so they can be indexed
> directly using the VIC, avoiding a +1/-1 dance here and there. This adds
> clarity to the error checking for various functions that return the VIC
> on success and zero on failure; we now explicitly check for 0 instead of
> just subtracting one from an unsigned type.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> 
> ---
> 
> This is on top of
> 
> commit 4c6bcf44549907cb50b67f98eb13717a4adc6b33
> Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Date:   Mon Nov 16 21:05:12 2015 +0200
> 
>     drm/edid: Make the detailed timing CEA/HDMI mode fixup accept up to 5kHz clock difference
> 
> in drm-intel/topic/drm-misc
> ---
>  drivers/gpu/drm/drm_edid.c | 84 ++++++++++++++++++++++++----------------------
>  1 file changed, 43 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index c214f1246cb4..aea09eae407e 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
<snip>
> @@ -2713,16 +2716,16 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
>  	list_for_each_entry(mode, &connector->probed_modes, head) {
>  		const struct drm_display_mode *cea_mode = NULL;
>  		struct drm_display_mode *newmode;
> -		u8 mode_idx = drm_match_cea_mode(mode) - 1;
> +		u8 vic = drm_match_cea_mode(mode);
>  		unsigned int clock1, clock2;
>  
> -		if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
> -			cea_mode = &edid_cea_modes[mode_idx];
> +		if (vic > 0 && vic < ARRAY_SIZE(edid_cea_modes)) {

Maybe add some sort of vic_is_valid() helpers to avoid duplicating
these in so many places?

Otherwise I like it.

> +			cea_mode = &edid_cea_modes[vic];
>  			clock2 = cea_mode_alternate_clock(cea_mode);
>  		} else {
> -			mode_idx = drm_match_hdmi_mode(mode) - 1;
> -			if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
> -				cea_mode = &edid_4k_modes[mode_idx];
> +			vic = drm_match_hdmi_mode(mode);
> +			if (vic > 0 && vic < ARRAY_SIZE(edid_4k_modes)) {
> +				cea_mode = &edid_4k_modes[vic];
>  				clock2 = hdmi_mode_alternate_clock(cea_mode);
>  			}
>  		}
> @@ -2773,17 +2776,17 @@ drm_display_mode_from_vic_index(struct drm_connector *connector,
>  {
>  	struct drm_device *dev = connector->dev;
>  	struct drm_display_mode *newmode;
> -	u8 cea_mode;
> +	u8 vic;
>  
>  	if (video_db == NULL || video_index >= video_len)
>  		return NULL;
>  
>  	/* CEA modes are numbered 1..127 */
> -	cea_mode = (video_db[video_index] & 127) - 1;
> -	if (cea_mode >= ARRAY_SIZE(edid_cea_modes))
> +	vic = (video_db[video_index] & 127);
> +	if (vic == 0 || vic >= ARRAY_SIZE(edid_cea_modes))
>  		return NULL;
>  
> -	newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
> +	newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
>  	if (!newmode)
>  		return NULL;
>  
> @@ -2878,8 +2881,7 @@ static int add_hdmi_mode(struct drm_connector *connector, u8 vic)
>  	struct drm_device *dev = connector->dev;
>  	struct drm_display_mode *newmode;
>  
> -	vic--; /* VICs start at 1 */
> -	if (vic >= ARRAY_SIZE(edid_4k_modes)) {
> +	if (vic == 0 || vic >= ARRAY_SIZE(edid_4k_modes)) {
>  		DRM_ERROR("Unknown HDMI VIC: %d\n", vic);
>  		return 0;
>  	}
> @@ -3170,24 +3172,24 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
>  {
>  	const struct drm_display_mode *cea_mode;
>  	int clock1, clock2, clock;
> -	u8 mode_idx;
> +	u8 vic;
>  	const char *type;
>  
>  	/*
>  	 * allow 5kHz clock difference either way to account for
>  	 * the 10kHz clock resolution limit of detailed timings.
>  	 */
> -	mode_idx = drm_match_cea_mode_clock_tolerance(mode, 5) - 1;
> -	if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
> +	vic = drm_match_cea_mode_clock_tolerance(mode, 5);
> +	if (vic > 0 && vic < ARRAY_SIZE(edid_cea_modes)) {
>  		type = "CEA";
> -		cea_mode = &edid_cea_modes[mode_idx];
> +		cea_mode = &edid_cea_modes[vic];
>  		clock1 = cea_mode->clock;
>  		clock2 = cea_mode_alternate_clock(cea_mode);
>  	} else {
> -		mode_idx = drm_match_hdmi_mode_clock_tolerance(mode, 5) - 1;
> -		if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
> +		vic = drm_match_hdmi_mode_clock_tolerance(mode, 5);
> +		if (vic > 0 && vic < ARRAY_SIZE(edid_4k_modes)) {
>  			type = "HDMI";
> -			cea_mode = &edid_4k_modes[mode_idx];
> +			cea_mode = &edid_4k_modes[vic];
>  			clock1 = cea_mode->clock;
>  			clock2 = hdmi_mode_alternate_clock(cea_mode);
>  		} else {
> @@ -3205,7 +3207,7 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
>  		return;
>  
>  	DRM_DEBUG("detailed mode matches %s VIC %d, adjusting clock %d -> %d\n",
> -		  type, mode_idx + 1, mode->clock, clock);
> +		  type, vic, mode->clock, clock);
>  	mode->clock = clock;
>  }
>  
> -- 
> 2.1.4

-- 
Ville Syrjälä
Intel OTC