From 863ee050726b67db82869e8e4221a7385a28b067 Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Sat, 2 Jan 2016 23:06:36 +0100 Subject: [PATCH 1/3] clocksource/drivers: Fix dependencies for !HAS_IOMEM archs Not every arch has io memory. So, unbreak the build by fixing the dependencies. Signed-off-by: Richard Weinberger Signed-off-by: Daniel Lezcano --- drivers/clocksource/Kconfig | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index b251013eef0a..796efbe7bea5 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -152,7 +152,7 @@ config CLKSRC_EFM32 config CLKSRC_LPC32XX bool "Clocksource for LPC32XX" if COMPILE_TEST - depends on GENERIC_CLOCKEVENTS + depends on GENERIC_CLOCKEVENTS && HAS_IOMEM select CLKSRC_MMIO select CLKSRC_OF help @@ -160,6 +160,7 @@ config CLKSRC_LPC32XX config CLKSRC_PISTACHIO bool "Clocksource for Pistachio SoC" if COMPILE_TEST + depends on HAS_IOMEM select CLKSRC_OF help Enables the clocksource for the Pistachio SoC. @@ -269,7 +270,7 @@ config SYS_SUPPORTS_SH_CMT config MTK_TIMER bool "Mediatek timer driver" if COMPILE_TEST - depends on GENERIC_CLOCKEVENTS + depends on GENERIC_CLOCKEVENTS && HAS_IOMEM select CLKSRC_OF select CLKSRC_MMIO help @@ -365,20 +366,20 @@ config CLKSRC_PXA config H8300_TMR8 bool "Clockevent timer for the H8300 platform" if COMPILE_TEST - depends on GENERIC_CLOCKEVENTS + depends on GENERIC_CLOCKEVENTS && HAS_IOMEM help This enables the 8 bits timer for the H8300 platform. config H8300_TMR16 bool "Clockevent timer for the H83069 platform" if COMPILE_TEST - depends on GENERIC_CLOCKEVENTS + depends on GENERIC_CLOCKEVENTS && HAS_IOMEM help This enables the 16 bits timer for the H8300 platform with the H83069 cpu. config H8300_TPU bool "Clocksource for the H8300 platform" if COMPILE_TEST - depends on GENERIC_CLOCKEVENTS + depends on GENERIC_CLOCKEVENTS && HAS_IOMEM help This enables the clocksource for the H8300 platform with the H8S2678 cpu. @@ -391,6 +392,7 @@ config CLKSRC_IMX_GPT config CLKSRC_ST_LPC bool "Low power clocksource found in the LPC" if COMPILE_TEST select CLKSRC_OF if OF + depends on HAS_IOMEM help Enable this option to use the Low Power controller timer as clocksource. From 03724ac3d48f8f0e3caf1d30fa134f8fd96c94e2 Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Fri, 8 Jan 2016 14:21:31 +0100 Subject: [PATCH 2/3] clocksource/drivers/fsl_ftm_timer: Fix CLKSRC_MMIO dependency Select CLKSRC_MMIO when FSL_FTM_TIMER is enabled. Otherwise it fails to compile on i386 with COMPILE_TEST=y. " on i386: when CLKSRC_MMIO is not enabled: drivers/built-in.o: In function `ftm_timer_init': fsl_ftm_timer.c:(.init.text+0x6842): undefined reference to `clocksource_mmio_readl_up' fsl_ftm_timer.c:(.init.text+0x6855): undefined reference to `clocksource_mmio_init' " Reported-by: Randy Dunlap Signed-off-by: Daniel Lezcano --- drivers/clocksource/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 796efbe7bea5..56777f04d2d9 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -257,6 +257,7 @@ config CLKSRC_SAMSUNG_PWM config FSL_FTM_TIMER bool "Freescale FlexTimer Module driver" if COMPILE_TEST depends on GENERIC_CLOCKEVENTS + select CLKSRC_MMIO help Support for Freescale FlexTimer Module (FTM) timer. From f9eccf24615672896dc13251410c3f2f33a14f95 Mon Sep 17 00:00:00 2001 From: Roman Volkov Date: Fri, 1 Jan 2016 16:24:41 +0300 Subject: [PATCH 3/3] clocksource/drivers/vt8500: Increase the minimum delta The vt8500 clocksource driver declares itself as capable to handle the minimum delay of 4 cycles by passing the value into clockevents_config_and_register(). The vt8500_timer_set_next_event() requires the passed cycles value to be at least 16. The impact is that userspace hangs in nanosleep() calls with small delay intervals. This problem is reproducible in Linux 4.2 starting from: c6eb3f70d448 ('hrtimer: Get rid of hrtimer softirq') From Russell King, more detailed explanation: "It's a speciality of the StrongARM/PXA hardware. It takes a certain number of OSCR cycles for the value written to hit the compare registers. So, if a very small delta is written (eg, the compare register is written with a value of OSCR + 1), the OSCR will have incremented past this value before it hits the underlying hardware. The result is, that you end up waiting a very long time for the OSCR to wrap before the event fires. So, we introduce a check in set_next_event() to detect this and return -ETIME if the calculated delta is too small, which causes the generic clockevents code to retry after adding the min_delta specified in clockevents_config_and_register() to the current time value. min_delta must be sufficient that we don't re-trip the -ETIME check - if we do, we will return -ETIME, forward the next event time, try to set it, return -ETIME again, and basically lock the system up. So, min_delta must be larger than the check inside set_next_event(). A factor of two was chosen to ensure that this situation would never occur. The PXA code worked on PXA systems for years, and I'd suggest no one changes this mechanism without access to a wide range of PXA systems, otherwise they're risking breakage." Cc: stable@vger.kernel.org Cc: Russell King Acked-by: Alexey Charkov Signed-off-by: Roman Volkov Signed-off-by: Daniel Lezcano --- drivers/clocksource/vt8500_timer.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/clocksource/vt8500_timer.c b/drivers/clocksource/vt8500_timer.c index a92e94b40b5b..dfc3bb410b00 100644 --- a/drivers/clocksource/vt8500_timer.c +++ b/drivers/clocksource/vt8500_timer.c @@ -50,6 +50,8 @@ #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) +#define MIN_OSCR_DELTA 16 + static void __iomem *regbase; static cycle_t vt8500_timer_read(struct clocksource *cs) @@ -80,7 +82,7 @@ static int vt8500_timer_set_next_event(unsigned long cycles, cpu_relax(); writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL); - if ((signed)(alarm - clocksource.read(&clocksource)) <= 16) + if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA) return -ETIME; writel(1, regbase + TIMER_IER_VAL); @@ -151,7 +153,7 @@ static void __init vt8500_timer_init(struct device_node *np) pr_err("%s: setup_irq failed for %s\n", __func__, clockevent.name); clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ, - 4, 0xf0000000); + MIN_OSCR_DELTA * 2, 0xf0000000); } CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);