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Subject[patch 098/101] video/aty/mach64_ct.c: fix bogus delay loop
From: David Miller <davem@davemloft.net>

[PATCH] video/aty/mach64_ct.c: fix bogus delay loop

CT based mach64 cards were reported to hang on sparc64 boxes when
compiled with gcc-4.1.x and later.

Looking at this piece of code, it's no surprise. A critical
delay was implemented as an empty for() loop, and gcc 4.0.x
and previous did not optimize it away, so we did get a delay.

But gcc-4.1.x and later can optimize it away, and we get crashes.

Use a real udelay() to fix this. Fix verified on SunBlade100.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

---
drivers/video/aty/mach64_ct.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- linux-2.6.20.1.orig/drivers/video/aty/mach64_ct.c
+++ linux-2.6.20.1/drivers/video/aty/mach64_ct.c
@@ -598,7 +598,6 @@ static void aty_resume_pll_ct(const stru
struct atyfb_par *par = info->par;

if (par->mclk_per != par->xclk_per) {
- int i;
/*
* This disables the sclk, crashes the computer as reported:
* aty_st_pll_ct(SPLL_CNTL2, 3, info);
@@ -614,7 +613,7 @@ static void aty_resume_pll_ct(const stru
* helps for Rage Mobilities that sometimes crash when
* we switch to sclk. (Daniel Mantione, 13-05-2003)
*/
- for (i=0;i<=0x1ffff;i++);
+ udelay(500);
}

aty_st_pll_ct(PLL_REF_DIV, pll->ct.pll_ref_div, par);
--
-
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