Messages in this thread Patch in this message | | | Date | Wed, 07 Mar 2007 09:12:13 -0800 | From | Greg KH <> | Subject | [patch 098/101] video/aty/mach64_ct.c: fix bogus delay loop |
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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); -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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