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<body><span class="vcard"><a class="email" href="mailto:sielicki@yandex.com" title="Nicholas Sielicki <sielicki@yandex.com>"> <span class="fn">Nicholas Sielicki</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [SKL,IVB] HDMI and DP: EDID-supplied BPP is not always properly clamped."
href="https://bugs.freedesktop.org/show_bug.cgi?id=99250">bug 99250</a>
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<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>WONTFIX
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [SKL,IVB] HDMI and DP: EDID-supplied BPP is not always properly clamped."
href="https://bugs.freedesktop.org/show_bug.cgi?id=99250#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - [SKL,IVB] HDMI and DP: EDID-supplied BPP is not always properly clamped."
href="https://bugs.freedesktop.org/show_bug.cgi?id=99250">bug 99250</a>
from <span class="vcard"><a class="email" href="mailto:sielicki@yandex.com" title="Nicholas Sielicki <sielicki@yandex.com>"> <span class="fn">Nicholas Sielicki</span></a>
</span></b>
<pre>HDMI 1.3A spec says the following
<span class="quote">> 6.2.4 Color Depth Requirements
>
> HDMI Sources and Sinks may support color depths of 24, 30, 36 and/or 48 bits
> per pixel. All HDMI Sources and Sinks shall support 24 bits per pixel. Color
> depths greater than 24 bits are defined to be “Deep Color” modes. All Deep
> Color modes are optional though if an HDMI Source or Sink supports any Deep
> Color mode, it shall support 36-bit mode.
>
> For each supported Deep Color mode, RGB 4:4:4 shall be supported and optionally
> YCBCR 4:4:4 may be supported.
>
> YCBCR 4:2:2 is not permitted for any Deep Color mode.
>
> An HDMI Sink shall support all EDID-indicated Deep Color modes on all
> EDID-indicated video formats except if that combination exceeds the
> Max_TMDS_Clock indication.
>
> An HDMI Source shall not send any Deep Color mode to a Sink that does not
> indicate support for that mode.</span >
The take away: it is illegal for DC_30bit to be set without DC_36bit also being
set.
The EDID claims the following:
<span class="quote">> CEA extension block
> Extension version: 3
> 30 bytes of CEA data
> <...>
> Vendor-specific data block, OUI 000c03 (HDMI)
> Source physical address 1.0.0.0
> DC_30bit</span >
Note the lack of DC_36bit.
While i915 is technically sending DC_36bit (a deep color mode) to a sink that
does not indicate support for that mode, the monitor clearly violated the spec
first and in a worse way. Had the monitor not violated the spec, i915 would not
have violated the spec.
So I think this can be chalked up as a bad monitor operating outside the spec.
I'm going to close this bug.
(Thank you to everyone on #intel-gfx for the help.)</pre>
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