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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - Regression: EDP panel flickers with linux 5.1+"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110675#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - Regression: EDP panel flickers with linux 5.1+"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110675">bug 110675</a>
from <span class="vcard"><a class="email" href="mailto:ville.syrjala@linux.intel.com" title="Ville Syrjala <ville.syrjala@linux.intel.com>"> <span class="fn">Ville Syrjala</span></a>
</span></b>
<pre>The immediate difference I see is:
[ 12.400643] [drm:intel_dump_pipe_config] dp m_n: lanes: 2; gmch_m: 5146655,
gmch_n: 8388608, link_m: 285925, link_n: 524288, tu: 64
vs.
[ 12.465994] [drm:intel_dump_pipe_config] dp m_n: lanes: 2; gmch_m: 20054,
gmch_n: 32768, link_m: 17825, link_n: 32768, tu: 64
Hmm. The relevant commit 53ca2edcf033 ("drm: Change limited M/N quirk to
constant N quirk.") is already in both kernels so these really should be
identical. I can't see how the quirk could get applied to only dp_m2_n2 but not
dp_m_n.
Can you try something silly like:
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7061,7 +7061,7 @@ static void compute_m_n(unsigned int m, unsigned int n,
* specified fixed N value for asynchronous clock mode,
* which the devices expect also in synchronous clock mode.
*/
- if (constant_n)
+ if (1||constant_n)
*ret_n = 0x8000;
else
*ret_n = min_t(unsigned int, roundup_pow_of_two(n),
DATA_LINK_N_MAX);</pre>
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