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fbdev/atyfb: Fix DSP config on some PowerMacs & PowerBooks
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. There are questions as to whether this should be extended to other platforms or maybe made dependent on specific chip types, but in the meantime, this has been tested on various powermacs and works for them so let's commit it. Signed-off-by: Risto Suominen <Risto.Suominen@gmail.com> Tested-by: Michael Pettersson <mike@it.uu.se> Cc: <stable@kernel.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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@ -8,6 +8,9 @@
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#include <asm/io.h>
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#include <video/mach64.h>
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#include "atyfb.h"
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#ifdef CONFIG_PPC
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#include <asm/machdep.h>
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#endif
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#undef DEBUG
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@ -536,6 +539,14 @@ static int __devinit aty_init_pll_ct(const struct fb_info *info,
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pll->ct.xclk_post_div_real = postdividers[xpost_div];
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pll->ct.mclk_fb_div = q * pll->ct.xclk_post_div_real / 8;
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#ifdef CONFIG_PPC
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if (machine_is(powermac)) {
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/* Override PLL_EXT_CNTL & 0x07. */
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pll->ct.xclk_post_div = xpost_div;
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pll->ct.xclk_ref_div = 1;
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}
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#endif
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#ifdef DEBUG
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pllmclk = (1000000 * pll->ct.mclk_fb_mult * pll->ct.mclk_fb_div) /
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(par->ref_clk_per * pll->ct.pll_ref_div);
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