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

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

On Wed, Jul 05, 2017 at 08:48:40AM +0530, Sharma, Shashank wrote:
> 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.

Why would bit 0 be set? That would sound like a bug in the mode parsing.

> 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

-- 
Ville Syrjälä
Intel OTC
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