[PATCH resend] cs5535-clockevt: don't ignore MFGPT on SMP-capablekernels

From: Jens Rottmann
Date: Mon Feb 06 2012 - 03:27:19 EST

cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels

On SMP-capable kernels (e.g. generic distro kernel) the cs5535-clockevt driver
loads but is not actually used.

Setting cpumask to cpu_all_mask works for UP-only kernels, but if compiled for
SMP - though still running on the same UP hardware -
kernel/time/tick-common.c:tick_check_new_device() reads this as "non-cpu-local"
and silently ignores the device.

If we leave cpumask unset clockevents_register_device() will initialize it and
the cs5535-clockevt driver will be used no matter how the kernel was compiled.
Should anyone ever manage to stick a CS553x in an SMP system (is this even
possible?) then a warning will be printed. This is fine as the cs5535-clockevt
driver was never written/tested for SMP.

If bisecting led you here this patch may have exposed a pre-existing MFGPT
problem. Configure for UP-only and re-check.

Signed-off-by: Jens Rottmann <JRottmann@xxxxxxxxxxxxxxxxxx>
Acked-by: Andres Salomon <dilinger@xxxxxxxxxx>

Hi again,

could you please take this, for linux-next?


--- linux-3.2-rc6/drivers/clocksource/cs5535-clockevt.c
+++ use_mfgpt_on_smp_kernels/drivers/clocksource/cs5535-clockevt.c
@@ -100,7 +100,6 @@ static struct clock_event_device cs5535_
.set_mode = mfgpt_set_mode,
.set_next_event = mfgpt_next_event,
.rating = 250,
- .cpumask = cpu_all_mask,
.shift = 32


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