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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2005-06-10 14:19:02 +1000
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-09 21:33:35 -0700
commit0086b5ec7834b78358dea3f713275a9ae2b229ec (patch)
tree589b4166efe6ab929ee25b20b2e89935efba504e /drivers/macintosh
parent243cd55e021baf28babdd88112ac03ae5cd4bb9c (diff)
[PATCH] ppc32: Fix nasty sleep/wakeup problem
Despite all the care lately in making the powermac sleep/wakeup as robust as possible, there is still a nasty related to the use of cpufreq on PMU based machines. Unfortunately, it affects paulus old powerbook so I have to fix it :) We didn't manage to understand what is precisely going on, it leads to memory corruption and might have to do with RAM not beeing properly refreshed when a cpufreq transition is done right before the sleep. The best workaround (and less intrusive at this point) we could come up with is included in this patch. We basically do _not_ force a switch to high speed on suspend anymore (that is what is causing the problem) on those machines. We still force a speed switch on wakeup (since we don't know what speed we are coming back from sleep at, and that seems to work fine). Since, during this short interval, the actual CPU speed might be incorrect, we also hack around by multiplying loops_per_jiffy by 2 (max speed factor on those machines) during early wakeup stage to make sure udelay's during that time aren't too short. For after 2.6.12, we'll change udelay implementation to use the CPU timebase (which is always constant) instead like we do on ppc64 and thus get rid of all those problems. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/macintosh')
-rw-r--r--drivers/macintosh/via-pmu.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/macintosh/via-pmu.c b/drivers/macintosh/via-pmu.c
index bb9f4044c74..b941ee22099 100644
--- a/drivers/macintosh/via-pmu.c
+++ b/drivers/macintosh/via-pmu.c
@@ -2593,6 +2593,9 @@ powerbook_sleep_Core99(void)
/* Restore VIA */
restore_via_state();
+ /* tweak LPJ before cpufreq is there */
+ loops_per_jiffy *= 2;
+
/* Restore video */
pmac_call_early_video_resume();
@@ -2613,6 +2616,9 @@ powerbook_sleep_Core99(void)
pmu_request(&req, NULL, 2, PMU_SET_INTR_MASK, pmu_intr_mask);
pmu_wait_complete(&req);
+ /* Restore LPJ, cpufreq will adjust the cpu frequency */
+ loops_per_jiffy /= 2;
+
pmac_wakeup_devices();
return 0;