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<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [BDW][Audio][HD-A Display] DP/HDMI audio playback abnormal"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91410#c16">Comment # 16</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [BDW][Audio][HD-A Display] DP/HDMI audio playback abnormal"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91410">bug 91410</a>
from <span class="vcard"><a class="email" href="mailto:han.lu@intel.com" title="Lu, Han <han.lu@intel.com>"> <span class="fn">Lu, Han</span></a>
</span></b>
<pre>(In reply to Jani Nikula from <a href="show_bug.cgi?id=91410#c15">comment #15</a>)
<span class="quote">> (In reply to Lu, Han from <a href="show_bug.cgi?id=91410#c14">comment #14</a>)
> > Regression?
> > YES
>
> Can you bisect please?</span >
We can ask our QA to help bisect. Also could GFX expert involve to give a quick
review please?
With the diagnose patch, when the issue be reproduced, it looks like the
register LCPLL_CTL was not changed but the return value of callback
get_display_clock_speed() changed from 337.5M to 540M:
1. no patch, playback OK;
(1) ./intel_reg read 0x46200 -> (0x00046200): 0x0000021b
(2) ./intel_reg read 0x130040 -> LCPLL_CTL (0x00130040): 0x48000000
(3) dmesg | grep lh -> None
2. no patch, playback slow;
(1) ./intel_reg read 0x46200 -> (0x00046200): 0x0000021b
(2) ./intel_reg read 0x130040 -> LCPLL_CTL (0x00130040): 0x48000000
(3) dmesg | grep lh -> None
3. apply "diagnose.patch", playback OK;
(1) ./intel_reg read 0x46200 -> (0x00046200): 0x0000021b
(2) ./intel_reg read 0x130040 -> LCPLL_CTL (0x00130040): 0x48000000
(3) dmesg | grep lh -> cdclk: 337500
4.apply "diagnose.patch", playback slow;
(1) ./intel_reg read 0x46200 -> (0x00046200): 0x0000021b
(2) ./intel_reg read 0x130040 -> LCPLL_CTL (0x00130040): 0x48000000
(3) dmesg | grep lh -> cdclk: 540000</pre>
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