[Intel-gfx] HDMI 4k modes VIC

Jani Nikula jani.nikula at linux.intel.com
Wed Oct 28 09:38:21 PDT 2015

On Wed, 28 Oct 2015, Damien Lespiau <damien.lespiau at intel.com> wrote:
> On Wed, Oct 28, 2015 at 01:58:55PM +0000, Sharma, Shashank wrote:
>>    Hi Damien
>>    This is regarding one of the patches:
>>    drm: Add support for alternate clocks of 4k modes
>>    (3f2f653378112c1453c0d83c81746a9225e4bc75)
>>    I am seeing that from function drm_match_hdmi_mode we are not returning
>>    correct VIC's for 4k modes (listed in edid_4k_modes[])
>>    Looks like we are returning VIC=(1, 2, 3, 4) for 4K modes (3840x2160 at 30Hz,
>>    3840x2160 at 25Hz, 3840x2160 at 24Hz and 4096x2160 at 24Hz)
> drm_match_hdmi_mode() doesn't return the VIC for the AVI infoframe, but
> the VIC for the HDMI vendor specific infoframe. See section 8.2.3 of the
> HDMI 1.4 spec.
>>    But as per the CEA-861-F specs, the respective VIC should be (95, 94 and
>>    93). The VIC returned is being used for writing AVI IF in
>>    drm_hdmi_vendor_infoframe_from_display_mode.
> That's not the AVI infoframe, that's the HDMI vendor specific infoframe.
>>    Please help me to understand if there any specific reason for this, or am
>>    I missing something in interpretation ?
> Are you seeing a bug? it's totally possible, I've never used an actual
> conformance tool when I wrote that code, so it's likely buggy and the
> VIC in the AVI infoframe may well be wrong.

Possibly relevant

> -- 
> Damien
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Jani Nikula, Intel Open Source Technology Center

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