linux-kernel - Re: Mobility Radeon HD 4530/4570/545v: flicker in 1920x1080

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Date:	Wed, 4 Nov 2015 00:03:30 +0100
From:	Pavel Machek <pavel@....cz>
To:	Alex Deucher <alexdeucher@...il.com>
Cc:	Christian König <christian.koenig@....com>,
	"Deucher, Alexander" <alexander.deucher@....com>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	Maling list - DRI developers 
	<dri-devel@...ts.freedesktop.org>
Subject: Re: Mobility Radeon HD 4530/4570/545v: flicker in 1920x1080

Hi!


> >> >> >Any ideas?
> >> >>
> >> >> Alex probably knows more about this, but it sounds like problems with
> >> >> switching the memory clocks on 3D load.
> >> >
> >> >> Try to disable power management completely with radeon.dpm=0 on the kernel
> >> >> command line or nailing the hardware at a specific power level using
> >> >> sysfs.
> >> >
> >> > I tried that, but it still flickers.
> >>
> >> It's probably pll stability.  There seem to be a number of regressions
> >> since the pll code was rewritten to support matching the hdmi clocks
> >> more closely.  Does this patch help?
> >>
> >> diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c
> >> b/drivers/gpu/drm/radeon/atombios_crtc.c
> >> index dac78ad..b86f06a 100644
> >> --- a/drivers/gpu/drm/radeon/atombios_crtc.c
> >> +++ b/drivers/gpu/drm/radeon/atombios_crtc.c
> >> @@ -569,6 +569,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
> >>         radeon_crtc->pll_flags = 0;
> >>
> >>         if (ASIC_IS_AVIVO(rdev)) {
> >> +               radeon_crtc->pll_flags |= RADEON_PLL_PREFER_MINM_OVER_MAXP;
> >> +
> >>                 if ((rdev->family == CHIP_RS600) ||
> >>                     (rdev->family == CHIP_RS690) ||
> >>                     (rdev->family == CHIP_RS740))
> >>
> >
> > Help.. maybe... it is tricky to tell. It definitely does _not_ fix the
> > issue completely.
> 
> You could also try the old pll algorithm:

I reverted the patch above, and switched to the old algorithm.

The flicker is still there. (But maybe its less horrible, like with
RADEON_PLL_PREFER_MINM_OVER_MAXP).

Thanks,
								Pavel
								
-- 
(english) http://www.livejournal.com/~pavelmachek
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