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<base href="https://bugs.freedesktop.org/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - EDID valid check ignores errors in CEA blocks"
href="https://bugs.freedesktop.org/show_bug.cgi?id=80683">80683</a>
</td>
</tr>
<tr>
<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Summary</th>
<td>EDID valid check ignores errors in CEA blocks
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Reporter</th>
<td>stefan.bruens@rwth-aachen.de
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Version</th>
<td>DRI CVS
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/other
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr></table>
<p>
<div>
<pre>in linux/drivers/gpu/drm/drm_edid.c:
bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid)
{
...
if (csum) {
if (print_bad_edid) {
DRM_ERROR("EDID checksum is invalid, remainder is
%d\n", csum);
}
/* allow CEA to slide through, switches mangle this */
if (raw_edid[0] != 0x02)
goto bad;
}
...
return true;
---
i.e. CEA blocks are always reported as valid.
This occurs frequently for me with a Radeon 7750 and a Dell U2713HM connected
via DisplayPort, the I2C-over-AUX seems to be buggy and swallows single bytes.
If I change the "return true;" to "return !csum;" bad transfers are retried.</pre>
</div>
</p>
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