From: Paul Mackerras Date: Tue, 10 Oct 2006 03:51:00 +0000 (+1000) Subject: [POWERPC] Fix secondary CPU startup on old "powersurge" SMP powermacs X-Git-Tag: v2.6.19-rc2~144^2~2 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=d6a29252ad120457cd544d44b2fbea46a00734a7;p=linux-2.6-omap-h63xx.git [POWERPC] Fix secondary CPU startup on old "powersurge" SMP powermacs On the old "powersurge" SMP powermacs, the second CPU is started up by sending it an IPI, which has the side effect of stopping the timebase clock (so the secondary CPU's timebase can be synchronized with the primary's). The routine that did this used udelay, which will hang forever when the timebase is stopped, since udelay now spins until the timebase reaches a certain value. The end result is that the kernel would hang when bringing up the second CPU. This fixes it by using a simple loop which just does a fixed number of iterations to generate the delay. These old systems were all clocked at around 200 MHz or so, so a fixed number of iterations is acceptable. Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c index 574cd205b30..eeb2ae5ffc5 100644 --- a/arch/powerpc/platforms/powermac/smp.c +++ b/arch/powerpc/platforms/powermac/smp.c @@ -328,6 +328,7 @@ static void __init smp_psurge_kick_cpu(int nr) { unsigned long start = __pa(__secondary_start_pmac_0) + nr * 8; unsigned long a; + int i; /* may need to flush here if secondary bats aren't setup */ for (a = KERNELBASE; a < KERNELBASE + 0x800000; a += 32) @@ -340,7 +341,11 @@ static void __init smp_psurge_kick_cpu(int nr) mb(); psurge_set_ipi(nr); - udelay(10); + /* + * We can't use udelay here because the timebase is now frozen. + */ + for (i = 0; i < 2000; ++i) + barrier(); psurge_clr_ipi(nr); if (ppc_md.progress) ppc_md.progress("smp_psurge_kick_cpu - done", 0x354);