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

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 01 Dec 2015, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> 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@linux.intel.com>
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> 
>> ---
>> 
>> This is on top of
>> 
>> commit 4c6bcf44549907cb50b67f98eb13717a4adc6b33
>> Author: Ville Syrjälä <ville.syrjala@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?

Any thoughts on how that should handle CEA vs. HDMI VICs, comparing
against ARRAY_SIZE(edid_cea_modes) and ARRAY_SIZE(edid_4k_modes)?

Add versions of drm_match_*_mode*() that return struct drm_display_mode
* or NULL on errors?

BR,
Jani.


>
> 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

-- 
Jani Nikula, Intel Open Source Technology Center
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