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

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Message-ID: <20100731212509.GA3633@n2100.arm.linux.org.uk>
Date:	Sat, 31 Jul 2010 22:25:09 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Jeff Garzik <jeff@...zik.org>
Cc:	Ondrej Zary <linux@...nbow-software.org>,
	linux-fbdev@...r.kernel.org,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] cyber2000fb: fix machine hang on module load

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@...nbow-software.org>
>>
>> --- 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.
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