RE: [PATCH] drm/edid: ignore the CEA modes not defined in CEA-861-D

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

On Wed, 01 Jun 2022, "Tseng, William" <william.tseng@intel.com> wrote:
> Thanks, Jani.  This is the bug. 
>
> https://gitlab.freedesktop.org/drm/intel/-/issues/6153
>
> Sorry about my mistake.

Np. Please also attach the EDID you have to the bug.

Thanks,
Jani.

>
>
> Regards
> William
>
>
> -----Original Message-----
> From: Jani Nikula <jani.nikula@linux.intel.com> 
> Sent: Wednesday, June 1, 2022 5:57 PM
> To: Tseng, William <william.tseng@intel.com>; dri-devel@lists.freedesktop.org
> Cc: Lee, Shawn C <shawn.c.lee@intel.com>; Wayne Lin <waynelin@amd.com>
> Subject: RE: [PATCH] drm/edid: ignore the CEA modes not defined in CEA-861-D
>
> On Wed, 01 Jun 2022, "Tseng, William" <william.tseng@intel.com> wrote:
>> Thanks, Jani.
>> This is the issue ticket. 
>> https://gitlab.freedesktop.org/drm/intel/-/issues/6087#note_1400843
>
> Copy-paste fail? Does not seem right.
>
> BR,
> Jani.
>
>
> PS. Also, for some reason you added this in your mail:
>
> Reply-To: "20220531103421.11363-1-william.tseng@intel.com"
> 	<20220531103421.11363-1-william.tseng@intel.com>
>
>
>
>
>>
>>
>> Regards
>> William
>>
>> -----Original Message-----
>> From: Jani Nikula <jani.nikula@linux.intel.com>
>> Sent: Tuesday, May 31, 2022 7:07 PM
>> To: Tseng, William <william.tseng@intel.com>; 
>> dri-devel@lists.freedesktop.org
>> Cc: Lee, Shawn C <shawn.c.lee@intel.com>; Wayne Lin 
>> <waynelin@amd.com>; Tseng, William <william.tseng@intel.com>
>> Subject: Re: [PATCH] drm/edid: ignore the CEA modes not defined in 
>> CEA-861-D
>>
>> On Tue, 31 May 2022, Jani Nikula <jani.nikula@linux.intel.com> wrote:
>>> On Tue, 31 May 2022, William Tseng <william.tseng@intel.com> wrote:
>>>> This is a workaround for HDMI 1.4 sink which has a CEA mode with 
>>>> higher vic than what is defined in CEA-861-D.
>>>>
>>>> As an example, a HDMI 1.4 sink has the video format 2560x1080p to be 
>>>> displayed and the video format is indicated by both SVD (with vic 90 
>>>> and pictuure aspect ratio 64:27) and DTD.  When connecting to such 
>>>> sink, source can't output the video format in SVD because an error 
>>>> is returned by drm_hdmi_avi_infoframe_from_display_mode(), which 
>>>> can't fill the infoframe with pictuure aspect ratio 64:27 and the 
>>>> vic, which is originally 90 and is changed to 0 by drm_mode_cea_vic().
>>>>
>>>> To work around it, this patch ignores such CEA modes in
>>>> do_cea_modes() so the modes won't be processed in drm_hdmi_avi_infoframe_from_display_mode().
>>>> And only the video format in DTD can be dispalyed.
>>
>> I think we should also have a bug filed on this, with the offending EDID attached for posterity.
>>
>> BR,
>> Jani.
>>
>>
>>>>
>>>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>> Cc: Wayne Lin <waynelin@amd.com>
>>>> Cc: Lee Shawn C <shawn.c.lee@intel.com>
>>>> Signed-off-by: William Tseng <william.tseng@intel.com>
>>>> ---
>>>>  drivers/gpu/drm/drm_edid.c | 39
>>>> +++++++++++++++++++++++++-------------
>>>>  1 file changed, 26 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c 
>>>> index bc43e1b32092..a93f68878bfd 100644
>>>> --- a/drivers/gpu/drm/drm_edid.c
>>>> +++ b/drivers/gpu/drm/drm_edid.c
>>>> @@ -3982,6 +3982,19 @@ drm_display_mode_from_cea_vic(struct
>>>> drm_device *dev,  }  EXPORT_SYMBOL(drm_display_mode_from_cea_vic);
>>>>  
>>>> +static bool is_hdmi2_sink(const struct drm_connector *connector) {
>>>> +	/*
>>>> +	 * FIXME: sil-sii8620 doesn't have a connector around when
>>>> +	 * we need one, so we have to be prepared for a NULL connector.
>>>> +	 */
>>>> +	if (!connector)
>>>> +		return true;
>>>> +
>>>> +	return connector->display_info.hdmi.scdc.supported ||
>>>> +		connector->display_info.color_formats & 
>>>> +DRM_COLOR_FORMAT_YCBCR420; }
>>>> +
>>>>  static int
>>>>  do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len) 
>>>> { @@ -3993,6 +4006,19 @@ do_cea_modes(struct drm_connector 
>>>> *connector, const u8 *db, u8 len)
>>>>  
>>>>  		mode = drm_display_mode_from_vic_index(connector, db, len, i);
>>>>  		if (mode) {
>>>> +			u8 vic = svd_to_vic(db[i]);
>>>> +
>>>> +			if (!drm_valid_cea_vic(vic))
>>>> +				continue;
>>>
>>> drm_display_mode_from_vic_index() returns NULL in this case.
>>>
>>>> +
>>>> +			/*
>>>> +			 * HDMI 1.4 VIC range: 1 <= VIC <= 64 (CEA-861-D) but
>>>> +			 * HDMI 2.0 VIC range: 1 <= VIC <= 107 (CEA-861-F). So we
>>>> +			 * have to make sure we dont break HDMI 1.4 sinks.
>>>> +			 */
>>>> +			if (!is_hdmi2_sink(connector) && vic > 64)
>>>> +				continue;
>>>
>>> I'll need to double check if this is the right thing to do... but I 
>>> guess the question becomes if this shouldn't be within 
>>> drm_display_mode_from_vic_index().
>>>
>>> Duplicating the condition from drm_mode_cea_vic() is probably not a 
>>> good idea.
>>>
>>> The continues in both above branches leak the mode.
>>>
>>>
>>> BR,
>>> Jani.
>>>
>>>
>>>> +
>>>>  			/*
>>>>  			 * YCBCR420 capability block contains a bitmap which
>>>>  			 * gives the index of CEA modes from CEA VDB, which @@ -5846,19
>>>> +5872,6 @@ void drm_set_preferred_mode(struct drm_connector
>>>> *connector,  }  EXPORT_SYMBOL(drm_set_preferred_mode);
>>>>  
>>>> -static bool is_hdmi2_sink(const struct drm_connector *connector) -{
>>>> -	/*
>>>> -	 * FIXME: sil-sii8620 doesn't have a connector around when
>>>> -	 * we need one, so we have to be prepared for a NULL connector.
>>>> -	 */
>>>> -	if (!connector)
>>>> -		return true;
>>>> -
>>>> -	return connector->display_info.hdmi.scdc.supported ||
>>>> -		connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR420;
>>>> -}
>>>> -
>>>>  static u8 drm_mode_hdmi_vic(const struct drm_connector *connector,
>>>>  			    const struct drm_display_mode *mode)  {
>>
>> --
>> Jani Nikula, Intel Open Source Graphics Center
>
> --
> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center