Re: [PATCH v5 04/17] drm: add helper to validate ycbcr420 modes

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards

Shashank


On 7/4/2017 9:26 PM, Ville Syrjälä wrote:
> On Tue, Jul 04, 2017 at 07:41:51PM +0530, Shashank Sharma wrote:
>> YCBCR420 modes are supported only on HDMI 2.0 capable sources.
>> This patch adds a drm helper to validate YCBCR420-only mode
>> on a particular connector. This function will help pruning
>> the YCBCR420-only modes from the connector's modelist.
>>
>> V5: Introduced the patch in series.
>>
>> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/drm_edid.c         |  3 ++-
>>   drivers/gpu/drm/drm_modes.c        | 28 ++++++++++++++++++++++++++++
>>   drivers/gpu/drm/drm_probe_helper.c |  4 ++++
>>   include/drm/drm_edid.h             |  1 +
>>   include/drm/drm_modes.h            |  5 +++++
>>   5 files changed, 40 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index b879662..ad26c5e 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -2947,10 +2947,11 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
>>   }
>>   EXPORT_SYMBOL(drm_match_cea_mode);
>>   
>> -static bool drm_valid_cea_vic(u8 vic)
>> +bool drm_valid_cea_vic(u8 vic)
>>   {
>>   	return vic > 0 && vic < ARRAY_SIZE(edid_cea_modes);
>>   }
>> +EXPORT_SYMBOL(drm_valid_cea_vic);
>>   
>>   /**
>>    * drm_get_cea_aspect_ratio - get the picture aspect ratio corresponding to
>> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
>> index f2493b9..3b53c8e3 100644
>> --- a/drivers/gpu/drm/drm_modes.c
>> +++ b/drivers/gpu/drm/drm_modes.c
>> @@ -1083,6 +1083,34 @@ drm_mode_validate_size(const struct drm_display_mode *mode,
>>   }
>>   EXPORT_SYMBOL(drm_mode_validate_size);
>>   
>> +/**
>> + * drm_mode_ycbcr420_only - add 'ycbcr420-only' modes only when allowed
>> + * @mode: mode to check
>> + * @connector: drm connector under action
>> + *
>> + * This function is a helper which can be used to filter out any YCBCR420
>> + * only mode, when the source doesn't support it.
>> + *
>> + * Returns:
>> + * The mode status
>> + */
>> +enum drm_mode_status
>> +drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
>> +			   struct drm_connector *connector)
>> +{
>> +	u8 vic = drm_match_cea_mode(mode);
>> +	enum drm_mode_status status = MODE_OK;
>> +	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
>> +
>> +	if (drm_valid_cea_vic(vic) && test_bit(vic, hdmi->y420_vdb_modes)) {
> The drm_valid_cea_vic() check seems redundant to me.
> Why do you think we need it?
drm_match_cea_mode() returns 0 in case if a vic is not found. if we take 
that to test_bit() it will check bit 0
and give wrong results. So first we have to check valid vic, this is 
also an additional check for YCBCR420 mode
as they must have a valid vic
> Also I don't think this will compile since we don't have
> y420_vdb_modes[] yet.
Ah, now I recall the reason I wanted to give you, when you asked me to 
move this patch, before we add ycbcr420 modes.
So now this has to go after patch 5 right ? I would re-sequence 
accordingly.

- Shashank
>> +		if (!connector->ycbcr_420_allowed)
>> +			status = MODE_NO_420;
>> +	}
>> +
>> +	return status;
>> +}
>> +EXPORT_SYMBOL(drm_mode_validate_ycbcr420);
>> +
>>   #define MODE_STATUS(status) [MODE_ ## status + 3] = #status
>>   
>>   static const char * const drm_mode_status_names[] = {
>> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
>> index 00e6832..904966c 100644
>> --- a/drivers/gpu/drm/drm_probe_helper.c
>> +++ b/drivers/gpu/drm/drm_probe_helper.c
>> @@ -528,6 +528,10 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>>   		if (mode->status == MODE_OK)
>>   			mode->status = drm_mode_validate_pipeline(mode,
>>   								  connector);
>> +
>> +		if (mode->status == MODE_OK)
>> +			mode->status = drm_mode_validate_ycbcr420(mode,
>> +								  connector);
>>   	}
>>   
>>   prune:
>> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> index 89c0062..b55b2a7 100644
>> --- a/include/drm/drm_edid.h
>> +++ b/include/drm/drm_edid.h
>> @@ -477,4 +477,5 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name,
>>   struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
>>   					   int hsize, int vsize, int fresh,
>>   					   bool rb);
>> +bool drm_valid_cea_vic(u8 vic);
>>   #endif /* __DRM_EDID_H__ */
>> diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
>> index 94ac771..f8a1268 100644
>> --- a/include/drm/drm_modes.h
>> +++ b/include/drm/drm_modes.h
>> @@ -80,6 +80,7 @@ struct videomode;
>>    * @MODE_ONE_SIZE: only one resolution is supported
>>    * @MODE_NO_REDUCED: monitor doesn't accept reduced blanking
>>    * @MODE_NO_STEREO: stereo modes not supported
>> + * @MODE_NO_420: ycbcr 420 modes not supported
>>    * @MODE_STALE: mode has become stale
>>    * @MODE_BAD: unspecified reason
>>    * @MODE_ERROR: error condition
>> @@ -124,6 +125,7 @@ enum drm_mode_status {
>>   	MODE_ONE_SIZE,
>>   	MODE_NO_REDUCED,
>>   	MODE_NO_STEREO,
>> +	MODE_NO_420,
>>   	MODE_STALE = -3,
>>   	MODE_BAD = -2,
>>   	MODE_ERROR = -1
>> @@ -496,6 +498,9 @@ bool drm_mode_equal_no_clocks_no_stereo(const struct drm_display_mode *mode1,
>>   enum drm_mode_status drm_mode_validate_basic(const struct drm_display_mode *mode);
>>   enum drm_mode_status drm_mode_validate_size(const struct drm_display_mode *mode,
>>   					    int maxX, int maxY);
>> +enum drm_mode_status
>> +drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
>> +			   struct drm_connector *connector);
>>   void drm_mode_prune_invalid(struct drm_device *dev,
>>   			    struct list_head *mode_list, bool verbose);
>>   void drm_mode_sort(struct list_head *mode_list);
>> -- 
>> 2.7.4

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