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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [Intel G45] Screen turns blank when terminating a low res X server on a different low res KMS mode."
href="https://bugs.freedesktop.org/show_bug.cgi?id=61457#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [Intel G45] Screen turns blank when terminating a low res X server on a different low res KMS mode."
href="https://bugs.freedesktop.org/show_bug.cgi?id=61457">bug 61457</a>
from <span class="vcard"><a class="email" href="mailto:eich@pdx.freedesktop.org" title="Egbert Eich <eich@pdx.freedesktop.org>"> <span class="fn">Egbert Eich</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=61457#c4">comment #4</a>)
<span class="quote">>
> in order to set the WM to a constant value and disable the low-power
> switching.</span >
Hrm, right - WM == 'watermarks'. Darn acronyms :(
Ok, I've looked into this - it looks promising.
It is this code path that is causing the problems:
if (single_plane_enabled(enabled) &&
g4x_compute_srwm(dev, ffs(enabled) - 1,
sr_latency_ns,
&g4x_wm_info,
&g4x_cursor_wm_info,
&plane_sr, &cursor_sr)) {
I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN);
} ...
The problem occurs when the FW_BLC_SELF_EN bit is set after it has been unset
before.
The reason why the issue doesn't occur for larger modes seems to be that
g4x_compute_srwm() will return false for those.</pre>
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