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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - audio broken in 24Hz/24p since 3.11 (regression)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=69675#c15">Comment # 15</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - audio broken in 24Hz/24p since 3.11 (regression)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=69675">bug 69675</a>
from <span class="vcard"><a class="email" href="mailto:pierre-bugzilla@ossman.eu" title="Pierre Ossman <pierre-bugzilla@ossman.eu>"> <span class="fn">Pierre Ossman</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=69675#c4">comment #4</a>)
<span class="quote">> Something like this:
>
> diff --git a/drivers/gpu/drm/radeon/r600_hdmi.c
> b/drivers/gpu/drm/radeon/r600_hdmi.c
> index b0fa600..f7d2766 100644
> --- a/drivers/gpu/drm/radeon/r600_hdmi.c
> +++ b/drivers/gpu/drm/radeon/r600_hdmi.c
> @@ -63,7 +63,7 @@ static const struct radeon_hdmi_acr
> r600_hdmi_predefined_acr[] = {
> { 27027, 4096, 27027, 6272, 30030, 6144, 27027 }, /*
> 27.00*1.001 MHz */
> { 54000, 4096, 54000, 6272, 60000, 6144, 54000 }, /* 54.00
> MHz */
> { 54054, 4096, 54054, 6272, 60060, 6144, 54054 }, /*
> 54.00*1.001 MHz */
> - { 74175, 11648, 210937, 17836, 234375, 11648, 140625 }, /*
> 74.25/1.001 MHz */
> + { 74180, 11648, 210937, 17836, 234375, 11648, 140625 }, /*
> 74.25/1.001 MHz */
> { 74250, 4096, 74250, 6272, 82500, 6144, 74250 }, /* 74.25
> MHz */
> { 148351, 11648, 421875, 8918, 234375, 5824, 140625 }, /*
> 148.50/1.001 MHz */
> { 148500, 4096, 148500, 6272, 165000, 6144, 148500 }, /* 148.50
> MHz */</span >
This however does not improve things. But that was because the frequency was
actually 74176, not 74180 (damn all that rounded output).
With that fixed, it *seems* to work. But doing the numbers, the audio clock is
slightly off as those numbers assume a perfect 74.25/1.001 video clock, not the
74.176 approximation. And 33 kHz audio needs a changing CTS even with that. So
it doesn't seem like a robust approach IHMO. I vote for letting the hardware do
its magic.
Somewhat related, the calculation in r600_hdmi_calc_cts() is not very good as
it loses a tonne of precision (roughly ten bits' worth). Given the range of the
inputs, you might need to do the calculations in a 64-bit space.</pre>
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