| 3252a646aa2cf706b2a26433a8bd9cb2e5dce410 |
|
04-Jul-2014 |
Doug Anderson <dianders@chromium.org> |
clocksource: exynos_mct: Only use 32-bits where possible
The MCT has a nice 64-bit counter. That means that we _can_ register
as a 64-bit clocksource and sched_clock. ...but that doesn't mean we
should.
The 64-bit counter is read by reading two 32-bit registers. That
means reading needs to be something like:
- Read upper half
- Read lower half
- Read upper half and confirm that it hasn't changed.
That wouldn't be terrible, but:
- THe MCT isn't very fast to access (hundreds of nanoseconds).
- The clocksource is queried _all the time_.
In total system profiles of real workloads on ChromeOS, we've seen
exynos_frc_read() taking 2% or more of CPU time even after optimizing
the 3 reads above to 2 (see below).
The MCT is clocked at ~24MHz on all known systems. That means that
the 32-bit half of the counter rolls over every ~178 seconds. This
inspired an optimization in ChromeOS to cache the upper half between
calls, moving 3 reads to 2. ...but we can do better! Having a 32-bit
timer that flips every 178 seconds is more than sufficient for Linux.
Let's just use the lower half of the MCT.
Times on 5420 to do 1000000 gettimeofday() calls from userspace:
* Original code: 1323852 us
* ChromeOS cache upper half: 1173084 us
* ChromeOS + ldmia to optimize: 1045674 us
* Use lower 32-bit only (this code): 1014429 us
As you can see, the time used doesn't increase linearly with the
number of reads and we can make 64-bit work almost as fast as 32-bit
with a bit of assembly code. But since there's no real gain for
64-bit, let's go with the simplest and fastest implementation.
Note: with this change roughly half the time for gettimeofday() is
spent in exynos_frc_read(). The rest is timer / system call overhead.
Also note: this patch disables the use of the MCT on ARM64 systems
until we've sorted out how to make "cycles_t" always 32-bit. Really
ARM64 systems should be using arch timers anyway.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
| fdb06f66d53e3c9ba7eeab3c0629c450aee76937 |
|
04-Jul-2014 |
Doug Anderson <dianders@chromium.org> |
clocksource: exynos_mct: Use readl_relaxed/writel_relaxed
Using the __raw functions is discouraged. Update the file to
consistently use the proper functions.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
| 8bf13a4346996b5a53d5f0c64b0914693c818fc2 |
|
04-Jul-2014 |
Amit Daniel Kachhap <amit.daniel@samsung.com> |
clocksource: exynos_mct: Register the timer for stable udelay
This patch registers the exynos mct clocksource as the current timer
as it has constant clock rate. This will generate correct udelay for
the exynos platform and avoid using unnecessary calibrated
jiffies. This change has been tested on exynos5420 based board and
udelay is very close to expected.
Without this patch udelay() on exynos5400 / exynos5800 is wildly
inaccurate due to big.LITTLE not adjusting loops_per_jiffy correctly.
Also without this patch udelay() on exynos5250 can be innacruate
during transitions between frequencies < 800 MHz (you'll go 200 MHz ->
800 MHz -> 300 MHz and will run at 800 MHz for a time with the wrong
loops_per_jiffy).
[dianders: reworked and created version 3]
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 89e6a13b88c8bf7ce1011a8a69113f22889f4585 |
|
04-Jul-2014 |
Doug Anderson <dianders@chromium.org> |
clocksource: exynos_mct: Fix ftrace
In (93bfb76 clocksource: exynos_mct: register sched_clock callback) we
supported using the MCT as a scheduler clock. We properly marked
exynos4_read_sched_clock() as notrace. However, we then went and
called another function that _wasn't_ notrace. That means if you do:
cd /sys/kernel/debug/tracing/
echo function_graph > current_tracer
You'll get a crash.
Fix this (but still let other readers of the MCT be trace-enabled) by
adding an extra function. It's important to keep other users of MCT
traceable because the MCT is actually quite slow to access and we want
exynos4_frc_read() to show up in ftrace profiles if it's the
bottleneck.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 1d80415db64b54141ef02ae58bd2f273d0ac3c38 |
|
11-Jun-2014 |
Chirantan Ekbote <chirantan@chromium.org> |
clocksource: exynos_mct: Don't reset the counter during boot and resume
Unfortunately on some exynos systems, resetting the mct counter also
resets the architected timer counter. This can cause problems if the
architected timer driver has already been initialized because the kernel
will think that the counter has wrapped around, causing a big jump in
printk timestamps and delaying any scheduled clock events until the
counter reaches the value it had before it was reset.
The kernel code makes no assumptions about the initial value of the mct
counter so there is no reason from a software perspective to clear the
counter before starting it. This also fixes the problems described in
the previous paragraph.
Cc: Olof Johansson <olof@lixom.net>
Cc: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Chirantan Ekbote <chirantan@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 93bfb769752babdc4d3665a1fb166bb4e3ff927b |
|
02-May-2014 |
Vincent Guittot <vincent.guittot@linaro.org> |
clocksource: exynos_mct: register sched_clock callback
Use the clocksource mct-frc for sched_clock
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 8db6e5104b77de5d0b7002b95069da0992a34be9 |
|
16-Apr-2014 |
Krzysztof Kozlowski <k.kozlowski@samsung.com> |
clocksource: Exynos_mct: Register clock event after request_irq()
After hotplugging CPU1 the first call of interrupt handler for CPU1
oneshot timer was called on CPU0 because it fired before setting IRQ
affinity. Affected are SoCs where Multi Core Timer interrupts are
shared (SPI), e.g. Exynos 4210.
During setup of the MCT timers the clock event device should be
registered after setting the affinity for interrupt. This will prevent
starting the timer too early.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>,
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org,
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140416143316.299247848@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 30ccf03b4a6a2102a2219058bdc6d779dc637dd7 |
|
16-Apr-2014 |
Thomas Gleixner <tglx@linutronix.de> |
clocksource: Exynos_mct: Use irq_force_affinity() in cpu bringup
The starting cpu is not yet in the online mask so irq_set_affinity()
fails which results in per cpu timers for this cpu ending up on some
other online cpu, ususally cpu 0.
Use irq_force_affinity() which disables the online mask check and
makes things work.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>,
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org,
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140416143316.106665251@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
| 09e15176ded1faa7bd685b3b5b1213cf0240566e |
|
01-Mar-2014 |
Dan Carpenter <dan.carpenter@oracle.com> |
clocksource: exynos_mct: silence a static checker warning
My guess is we aren't going to have a 2 digit cpuid here any time soon
but the static checkers don't know that and complain that the snprintf()
could overflow.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
| 3581e56fd33b87ef485140c246d0db6c43fe4c58 |
|
13-Feb-2014 |
Pankaj Dubey <pankaj.dubey@samsung.com> |
clocksource: exynos_mct: remove unwanted header file inclusion
remove unwanted header file inclusion "asm/mach/time.h" from exynos_mct.c
Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 6c16dedfd4c49c6a7f410f171c6da3116834a23d |
|
01-Dec-2013 |
Chander Kashyap <chander.kashyap@linaro.org> |
clocksource: mct: extend mct to support 8 local interrupts for Exynos5420
Exynos5420 is octa-core SoC from Samsung. Hence extend exynos-mct clocksource
driver to support 8 local interrupts.
Also extend dts entries for 8 interrupts.
Signed-off-by: Chander Kashyap <chander.kashyap@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 5df718d84679936454e815451d748ccca0e9edad |
|
25-Sep-2013 |
Tomasz Figa <t.figa@samsung.com> |
clocksource: exynos_mct: Set IRQ affinity when the CPU goes online
Some variants of Exynos MCT, namely exynos4210-mct at the moment, use
normal, shared interrupts for local timers. This means that each
interrupt must have correct affinity set to fire only on CPU
corresponding to given local timer.
However after recent conversion of clocksource drivers to not use the
local timer API for local timer initialization any more, the point of
time when local timers get initialized changed and irq_set_affinity()
fails because the CPU is not marked as online yet.
This patch fixes this by moving the call to irq_set_affinity() to
CPU_ONLINE notification, so the affinity is being set when the CPU goes
online.
This fixes a regression introduced by commit
ee98d27df6 ARM: EXYNOS4: Divorce mct from local timer API
which rendered all Exynos4210 based boards unbootable due to
failing irq_set_affinity() making local timers inoperatible.
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
|
| 8c37bb3ac95b8ff953bd3c8bc8dd0a393d5ae989 |
|
19-Jun-2013 |
Paul Gortmaker <paul.gortmaker@windriver.com> |
clocksource+irqchip: delete __cpuinit usage from all related files
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the drivers/clocksource and drivers/irqchip uses of
the __cpuinit macros from all C files.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
|
| ee98d27df6827b5ba4bd99cb7d5cb1239b6a1a31 |
|
16-Feb-2013 |
Stephen Boyd <sboyd@codeaurora.org> |
ARM: EXYNOS4: Divorce mct from local timer API
Separate the mct local timers from the local timer API. This will
allow us to remove ARM local timer support in the near future and
gets us closer to moving this driver to drivers/clocksource.
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
|
| 7114cd749a12ff9fd64a2f6f04919760f45ab183 |
|
18-Jun-2013 |
Chander Kashyap <chander.kashyap@linaro.org> |
clocksource: exynos_mct: use (request/free)_irq calls for local timer registration
Replace the (setup/remove)_irq calls for local timer registration with
(request/free)_irq calls. This generalizes the local timer registration API.
Suggested by Mark Rutland.
Signed-off-by: Chander Kashyap <chander.kashyap@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 034c097ca27fb163754ee4f4e26f85559bece69b |
|
10-Apr-2013 |
Arnd Bergmann <arnd@arndb.de> |
clocksource: exynos_mct: remove platform header dependency
For the non-DT case, the mct_init() function requires access
to a couple of platform specific constants, but cannot include
the header files in case we are building for multiplatform.
This changes the interface to the platform so we pass all
the necessary data as arguments to mct_init.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
|
| f4636d0ad7eee4741ef5146080e9ce57b9e2de0b |
|
19-Apr-2013 |
Arnd Bergmann <arnd@arndb.de> |
clocksource: exynos_mct: fix build error on non-DT
There is currently no alternative implementation for of_irq_count
when the function is not defined, and the declaration is hidden,
so this works around calling an undeclared function. It should
really not be needed.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
|
| 354599f460ba79c9fb00f220e42de5a7509ceeb4 |
|
04-Apr-2013 |
Axel Lin <[axel.lin@ingics.com]> |
clocksource: mct: Add terminating entry for exynos_mct_ids table
The of_device_id table is supposed to be zero-terminated.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| d8acac566c9b8ba96c278bf17b8acd549c99e621 |
|
04-Apr-2013 |
Doug Anderson <[dianders@chromium.org]> |
clocksource: mct: Add missing semicolons in exynos_mct.c
The CLOCKSOURCE_OF_DECLARE lines were added without a semicolon at the
end. On my system this causes a compile-time error that looks like:
drivers/clocksource/exynos_mct.c:557:202: warning: comparison of distinct pointer types lacks a cast [enabled by default]
drivers/clocksource/exynos_mct.c:558:1: error: expected ',' or ';' before 'static'
The error didn't show up till now because there was an extra semicolon
at end of the CLOCKSOURCE_OF_DECLARE definition that was removed by
Arnd Bergmann in "clocksource: make CLOCKSOURCE_OF_DECLARE type safe"
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| ca9048ec31ab5e50c79bf18eccb79396c1f24b22 |
|
09-Mar-2013 |
Thomas Abraham <thomas.abraham@linaro.org> |
clocksource: mct: add support for mct clock setup
Add support for mct clock lookup and setup to ensure that the mct
clock is has been turned on.
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 415ac2e240f7f3e1b609f34ba7aa1c340589fdb1 |
|
09-Mar-2013 |
Thomas Abraham <thomas.abraham@linaro.org> |
clocksource: mct: use fin_pll clock as the tick clock source for mct
With the migration of Exynos4 clocks to use common clock framework, the
old styled 'xtal' clock is not used anymore. Instead, the clock 'fin_pll'
is used as the tick clock for mct controller.
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|
| 6938d75a8c1a1752f9fa7ef14a0c570036c7b73b |
|
09-Mar-2013 |
Thomas Abraham <thomas.abraham@linaro.org> |
ARM: EXYNOS: move mct driver to drivers/clocksource
Move the multi core timer (mct) driver to from mach-exynos
to drivers/clocksource and update the Kconfig and makefiles.
Cc: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
|