cyber2000fb: fix machine hang on module load
PATCH RESEND 1/1 cyber2000fb: fix machine hang on module load
Hello,
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.
drivers/video/cyber2000fb.c +1 -0
@@ -436,6 +436,7 @@ static void cyber2000fb_write_ramdac_ctrcyber2000fb_writeb (i |4 ,0x3cf , cfb);cyber2000fb_writeb (val,0x3c6 , cfb);cyber2000fb_writeb (i,0x3cf , cfb); +udelay (1 ); }static void cyber2000fb_set_timing (struct cfb_info *cfb,struct par_info *hw)
Signature · 1 line
Ondrej Zary
Quoted 7 lines · Ondrej Zary
Hello,
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.
This one on the other hand I think is rather too heavy.
What might be better is to re-code the last register write to use the x86 outb_p() stuff to slow it down, rather than using udelay(). Could you try something along those lines please?
Quoted 7 lines · On Tuesday 27 July 2010 18:25:11 Russell King - ARM Linux wrote:
Quoted 6 lines · Ondrej Zary
Hello,
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.
Quoted 8 lines
Quoted 2 lines
Add delay after RAMDAC control register write to prevent hangs on module load.
This one on the other hand I think is rather too heavy.
What might be better is to re-code the last register write to use the x86
outb_p()stuff to slow it down, rather than usingudelay(). Could you try something along those lines please?
Is this better?
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.
drivers/video/cyber2000fb.c +2 -0
@@ -436,6 +436,8 @@ static void cyber2000fb_write_ramdac_ctrcyber2000fb_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); }static void cyber2000fb_set_timing (struct cfb_info *cfb,struct par_info *hw)
Signature · 1 line
Ondrej Zary