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6a4dae5e13
The scheduler imposes a requirement to sched_clock() which is to stop the clock during suspend, if we don't do that any RT thread will be rescheduled in the future which might cause any sort of problems. This became an issue on OMAP when we converted omap-i2c.c to use threaded IRQs, it turned out that depending on how much time we spent on suspend, the I2C IRQ thread would end up being rescheduled so far in the future that I2C transfers would timeout and, because omap_hsmmc depends on an I2C-connected device to detect if an MMC card is inserted in the slot, our rootfs would just vanish. arch/arm/kernel/sched_clock.c already had an optional implementation (sched_clock_needs_suspend()) which would handle scheduler's requirement properly, what this patch does is simply to make that implementation non-optional. Note that this has the side-effect that printk timings won't reflect the actual time spent on suspend so other methods to measure that will have to be used. This has been tested with beagleboard XM (OMAP3630) and pandaboard rev A3 (OMAP4430). Suspend to RAM is now working after this patch. Thanks to Kevin Hilman for helping out with debugging. Acked-by: Kevin Hilman <khilman@ti.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
15 lines
449 B
C
15 lines
449 B
C
/*
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* sched_clock.h: support for extending counters to full 64-bit ns counter
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef ASM_SCHED_CLOCK
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#define ASM_SCHED_CLOCK
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extern void sched_clock_postinit(void);
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extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate);
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#endif
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