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. When working on s3fb, over a decade ago, ISTR needing a lot of MMIO register flushes -- dummy register reads -- to flush out just-written register writes.
-- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
