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<b><a class="bz_bug_link
bz_status_ASSIGNED "
title="ASSIGNED - [SKL, BIOS upgrade regression] distorted display after resume from suspend"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91697#c21">Comment # 21</a>
on <a class="bz_bug_link
bz_status_ASSIGNED "
title="ASSIGNED - [SKL, BIOS upgrade regression] distorted display after resume from suspend"
href="https://bugs.freedesktop.org/show_bug.cgi?id=91697">bug 91697</a>
from <span class="vcard"><a class="email" href="mailto:akshu.agrawal@intel.com" title="Akshu Agrawal <akshu.agrawal@intel.com>"> <span class="fn">Akshu Agrawal</span></a>
</span></b>
<pre>If we just enable the ‘DBUF Power Request’ bit in DBUF_CNTL, there is no
display corruption. IMO this bit is left in reset state as we are enabling the
PW2 in BIOS. Following change would also fix the issue:
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index af0bcfe..fd69c4c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5698,6 +5698,12 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv)
/* DPLL0 already enabed !? */
if (I915_READ(LCPLL1_CTL) & LCPLL_PLL_ENABLE) {
DRM_DEBUG_DRIVER("DPLL0 already running\n");
+ /* check for DBUF status and enable if in reset state */
+ if (!(I915_READ(DBUF_CTL) & DBUF_POWER_STATE)) {
+ I915_WRITE(DBUF_CTL, I915_READ(DBUF_CTL)
+ | DBUF_POWER_REQUEST);
+ POSTING_READ(DBUF_CTL);
+ }
return;
}</pre>
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