From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 16389] New PM-Code produces white screen on laptop display on
startup on an radeon x700
Date: Tue, 20 Jul 2010 16:08:49 GMT
Message-ID: <201007201608.o6KG8njp025314@demeter.kernel.org>
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https://bugzilla.kernel.org/show_bug.cgi?id=16389
--- Comment #5 from Alex Deucher 2010-07-20 16:08:48 ---
(In reply to comment #4)
> Looking at fdo-bug 22755 i found another way to put the screen into an usable
> stae after resolution switch:
> xrandr -s 1024x768; xrandr --output LVDS --off; xrandr --output LVDS --auto
> works (i think it is the same call as vbetool dpms off / on).
> Without turning the output off and on i get the white screen. Whats the
> difference between boot-time initialization of the screen (which does not work)
> and the initialization with the xrandr off / on call (which works) ?
Nothing. Both use the same path in the driver. I suspect this is a timing
issue with the LVDS. Your system probably needs a longer/shorter delay
somewhere in the LVDS dpms code. Can you try adjusting the delays in
radeon_legacy_lvds_dpms() in radeon_legacy_encoders.c? Can you also try
something like this:
diff --git a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
index bad77f4..5688a0c 100644
--- a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
+++ b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
@@ -108,6 +108,7 @@ static void radeon_legacy_lvds_dpms(struct drm_encoder
*encoder, int mode)
udelay(panel_pwr_delay * 1000);
WREG32(RADEON_LVDS_GEN_CNTL, lvds_gen_cntl);
WREG32_PLL(RADEON_PIXCLKS_CNTL, pixclks_cntl);
+ udelay(panel_pwr_delay * 1000);
break;
}
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