Re: [PATCH 1/3] cyber2000fb: fix machine hang on module load

From: Jeff Garzik
Date: Sat Jul 31 2010 - 18:37:37 EST

On 07/31/2010 05:25 PM, Russell King - ARM Linux wrote:
On Sat, Jul 31, 2010 at 05:21:33PM -0400, Jeff Garzik wrote:
On 07/31/2010 04:55 PM, Ondrej Zary wrote:
I was testing two CyberPro 2000 based PCI cards on x86 and the machine always
hanged completely when the cyber2000fb module was loaded. It seems that the
card hangs when some registers are accessed too quickly after writing RAMDAC
control register. With this patch, both card work.

Add delay after RAMDAC control register write to prevent hangs on module load.

Signed-off-by: Ondrej Zary<linux@xxxxxxxxxxxxxxxxxxxx>

--- linux-2.6.35-rc2-orig/drivers/video/cyber2000fb.c 2010-06-06 05:43:24.000000000 +0200
+++ linux-2.6.35-rc3/drivers/video/cyber2000fb.c 2010-07-27 23:12:37.000000000 +0200
@@ -436,6 +436,8 @@ static void cyber2000fb_write_ramdac_ctr
cyber2000fb_writeb(i | 4, 0x3cf, cfb);
cyber2000fb_writeb(val, 0x3c6, cfb);
cyber2000fb_writeb(i, 0x3cf, cfb);
+ /* prevent card lock-up observed on x86 with CyberPro 2000 */
+ cyber2000fb_readb(0x3cf, cfb);

IIRC, cyber2000 is basically an S3 graphics chip.

No such luck. It's a proprietary Integraphics chip, mainly used in
ARM Netwinders some 10 years ago. It's completely different from the
S3 chips such as Trio64.

Ah, I stand corrected. Maybe that was cyberfb I was remembering...


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