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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL] Watermark programming is broken when page flipping from linear to Y/Yf tiled frame buffers"
href="https://bugs.freedesktop.org/show_bug.cgi?id=98684">98684</a>
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<th>Summary</th>
<td>[SKL] Watermark programming is broken when page flipping from linear to Y/Yf tiled frame buffers
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>DRI git
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>tvrtko.ursulin@linux.intel.com
</td>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<pre>When flipping from linear to Y or Yf tiled frame buffer we get a FIFO underrun
and a black screen.
This can be reproduced with the kms_flip_tiling flip-to-Y-tiled and
flip-to-Yf-tiled testcases.
Test first displays a Y tiled fb to collect the reference CRC. Display
programming looks like this at that point:
DSPASURF (0x0007019c): 0x01100000
DSPACNTR (0x00070180): 0xc4803000 (enabled)
DSPASTRIDE (0x00070188): 0x00000040 (1)
(0x00070190): 0x0437077f
(0x0007018c): 0x00000000
DSPATILEOFF (0x000701a4): 0x00000000 (0, 0)
(0x000701ac): 0x01100020
(0x00070240): 0x80020079
(0x00070268): 0x00000000
Then the test flips to a linear fb, and back to the reference Y tiled fb. At
this point the plane register programming looks like:
DSPASURF (0x0007019c): 0x01100000
DSPACNTR (0x00070180): 0xc4803000 (enabled)
DSPASTRIDE (0x00070188): 0x00000040 (1)
(0x00070190): 0x0437077f
(0x0007018c): 0x00000000
DSPATILEOFF (0x000701a4): 0x00000000 (0, 0)
(0x000701ac): 0x01100020
(0x00070240): 0x80004004
(0x00070268): 0x00000000
Register 0x70240 (PLANE_WM_1_A_0) is different so probably wrong.
Scenario which tests the opposite flip direction. from Y/Yf to linear works
fine (subtests flip-changes-tiling-Y and flip-changes-tiling-Yf).</pre>
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