Messages in this thread | | | Subject | Re: [Linux-fbdev-devel] [PATCH] atyfb: fix distorted image on PowerMacs | From | Benjamin Herrenschmidt <> | Date | Wed, 04 Feb 2009 08:06:12 +1100 |
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On Tue, 2009-02-03 at 20:56 +0200, Ville Syrjälä wrote: > On Thu, Jan 22, 2009 at 10:12:04PM +0200, Ville Syrjälä wrote: > > On Thu, Jan 22, 2009 at 08:22:48PM +0200, Risto Suominen wrote: > > > Since the complete re-write in 2.6.10, some PowerMacs (At least PowerMac 5500 > > > and PowerMac G3 Beige rev A) with ATI Mach64 chip have suffered from unstable > > > columns in their framebuffer image. This seems to depend on a value (4) read > > > from PLL_EXT_CNTL register, which leads to incorrect DSP config parameters to > > > be written to the chip. This patch uses a value calculated by aty_init_pll_ct > > > instead, as a starting point. > > > > AFAICS it should be the right thing to do on other systems too. I have > > a good collection of mach64 pci cards and laptops so I'll try to find > > some time next week to test that theory on x86. > > Well, the experiment failed on the first Mobility I tried. The FIFO > calculations aren't obvious from the code and there's no mention how > to actually calculate them in the programming guide. So I guess special > casing powermacs is the best way forward.
There's one powermac with a M1 (the first clamshell ibook). I don't have such a machine however, it would be useful if somebody who did could test if the patch caused a regression there...
It's possible that we should instead base the code on the chip variant.
Ben.
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