linux-kernel - Re: [patch 07/41] fbdev/atyfb: Fix DSP config on some PowerMacs & PowerBooks

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Message-Id: <1233791475.4612.24.camel@pasglop>
Date:	Thu, 05 Feb 2009 10:51:15 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Justin Forbes <jmforbes@...uxtx.org>,
	Zwane Mwaikambo <zwane@....linux.org.uk>,
	"Theodore Ts'o" <tytso@....edu>,
	Randy Dunlap <rdunlap@...otime.net>,
	Dave Jones <davej@...hat.com>,
	Chuck Wolber <chuckw@...ntumlinux.com>,
	Chris Wedgwood <reviews@...cw.f00f.org>,
	Michael Krufky <mkrufky@...uxtv.org>,
	Chuck Ebbert <cebbert@...hat.com>,
	Domenico Andreoli <cavokz@...il.com>, Willy Tarreau <w@....eu>,
	Rodrigo Rubira Branco <rbranco@...checkpoint.com>,
	Jake Edge <jake@....net>, Eugene Teo <eteo@...hat.com>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Risto Suominen <Risto.Suominen@...il.com>
Subject: Re: [patch 07/41] fbdev/atyfb: Fix DSP config on some PowerMacs &
 PowerBooks

On Wed, 2009-02-04 at 10:46 -0800, Greg KH wrote:
> plain text document attachment
> (fbdev-atyfb-fix-dsp-config-on-some-powermacs-powerbooks.patch)
> 2.6.27-stable review patch.  If anyone has any objections, please let us know.

My only possible worry with that one is the first generation clamshell
iBook which uses a Mobility M1 chip, for which we haven't had anybody
testing whether this would break it or not ... 

So if anybody with such a machine is reading this, please holler...

Cheers,
Ben.

> ------------------
> 
> From: Risto Suominen <Risto.Suominen@...il.com>
> 
> commit 7fbb7cadd062baf299fd8b26a80ea99da0c3fe01 upstream.
> 
> 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@...il.com>
> Tested-by: Michael Pettersson <mike@...uu.se>
> Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  drivers/video/aty/mach64_ct.c |   11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> --- a/drivers/video/aty/mach64_ct.c
> +++ b/drivers/video/aty/mach64_ct.c
> @@ -8,6 +8,9 @@
>  #include <asm/io.h>
>  #include <video/mach64.h>
>  #include "atyfb.h"
> +#ifdef CONFIG_PPC
> +#include <asm/machdep.h>
> +#endif
>  
>  #undef DEBUG
>  
> @@ -536,6 +539,14 @@ static int __devinit aty_init_pll_ct(con
>  	pll->ct.xclk_post_div_real = postdividers[xpost_div];
>  	pll->ct.mclk_fb_div = q * pll->ct.xclk_post_div_real / 8;
>  
> +#ifdef CONFIG_PPC
> +	if (machine_is(powermac)) {
> +		/* Override PLL_EXT_CNTL & 0x07. */
> +		pll->ct.xclk_post_div = xpost_div;
> +		pll->ct.xclk_ref_div = 1;
> +	}
> +#endif
> +
>  #ifdef DEBUG
>  	pllmclk = (1000000 * pll->ct.mclk_fb_mult * pll->ct.mclk_fb_div) /
>  			(par->ref_clk_per * pll->ct.pll_ref_div);
> 
> --
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