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<body><span class="vcard"><a class="email" href="mailto:kenneth@whitecape.org" title="Kenneth Graunke <kenneth@whitecape.org>"> <span class="fn">Kenneth Graunke</span></a>
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<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [GEN8+] Hang when discarding a fragment if dual source blending is enabled but shader doesn't support it"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107306">bug 107306</a>
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<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [GEN8+] Hang when discarding a fragment if dual source blending is enabled but shader doesn't support it"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107306#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [GEN8+] Hang when discarding a fragment if dual source blending is enabled but shader doesn't support it"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107306">bug 107306</a>
from <span class="vcard"><a class="email" href="mailto:kenneth@whitecape.org" title="Kenneth Graunke <kenneth@whitecape.org>"> <span class="fn">Kenneth Graunke</span></a>
</span></b>
<pre>Fixed by:
commit 00fc56a68d21d7aa91b95f0eaacba59a96c466f5 (HEAD -> master)
Author: Danylo Piliaiev <<a href="mailto:danylo.piliaiev@gmail.com">danylo.piliaiev@gmail.com</a>>
Date: Fri Jul 20 12:54:42 2018 +0300
anv: Disable dual source blending when shader doesn't support it on gen8+
Dual source blending behaviour is undefined when shader doesn't
have second color output.
"If SRC1 is included in a src/dst blend factor and
a DualSource RT Write message is not used, results
are UNDEFINED. (This reflects the same restriction in DX APIs,
where undefined results are produced if “o1” is not written
by a PS – there are no default values defined)."
Dismissing fragment in such situation leads to a hang on gen8+
if depth test in enabled.
Since blending cannot be gracefully fixed in such case and the result
is undefined - blending is simply disabled.
v2 (Jason Ekstrand):
- Apply the workaround to each individual entry
- Emit a warning through debug_report
Signed-off-by: Danylo Piliaiev <<a href="mailto:danylo.piliaiev@globallogic.com">danylo.piliaiev@globallogic.com</a>>
Reviewed-by: Jason Ekstrand <<a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a>>
Reviewed-by: Kenneth Graunke <<a href="mailto:kenneth@whitecape.org">kenneth@whitecape.org</a>></pre>
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