linux-kernel - Re: [Linux-fbdev-devel] radeonfb lockup in .28-rc (bisected)

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Date:	Wed, 05 Nov 2008 08:36:00 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Paul Collins <paul@...ly.ondioline.org>
Cc:	James Cloos <cloos@...loos.com>,
	linux-fbdev-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Krzysztof Halasa <khc@...waw.pl>
Subject: Re: [Linux-fbdev-devel] radeonfb lockup in .28-rc (bisected)

On Tue, 2008-11-04 at 19:49 +1300, Paul Collins wrote:
> Benjamin Herrenschmidt <benh@...nel.crashing.org> writes:
> 
> > One thing you may want to try .. it will result in crap results on
> > screen but would help telling us if that's the cause, is to hack
> > radeonfb to round the image size to a multiple of 32 and see if that
> > stops the lockup.
> 
> I took a guess at how to do this and ended up with the patch below.
> 
> With the patch applied, the screen turns almost completely to gibberish
> at console handover and the machine hangs.  At the top I get two lines
> of old output from the previous boot.  (I'm pretty sure it's hung
> because the optical drive init happens after console handover, and I
> don't get the usual chunka-chunka noise.)
> 
> The corruption I get is very similar to what I got when I originally
> reported the problem when I was using my patched-in 12x24 font.  (I
> created the .psf version later and switched back to default 8x16 to
> verify my problem was the same as James's.)
> 
> 
> diff --git a/drivers/video/aty/radeon_accel.c b/drivers/video/aty/radeon_accel.c
> index 8718f73..848e9bc 100644
> --- a/drivers/video/aty/radeon_accel.c
> +++ b/drivers/video/aty/radeon_accel.c
> @@ -208,7 +208,11 @@ static void radeonfb_prim_imageblit(struct radeonfb_info *rinfo,
>  	 * work ok for me without that and the doco doesn't seem to imply
>  	 * there is such a restriction.
>  	 */
> -	OUTREG(DST_WIDTH_HEIGHT, (image->width << 16) | image->height);
> +	{
> +		/* Hack attack. */
> +		int width = ((image->width - 1) / 32 + 1) * 32;
> +		OUTREG(DST_WIDTH_HEIGHT, (width << 16) | image->height);
> +	}
>  
>  	src_bytes = (((image->width * image->depth) + 7) / 8) * image->height;
>  	dwords = (src_bytes + 3) / 4;

Oh and you also need to change the src_bytes calculation 

Ben.

> 

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