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  1. 15 12月, 2015 6 次提交
  3. 17 11月, 2015 1 次提交
    • A
      clocksource: Disallow drivers for ARCH_USES_GETTIMEOFFSET · 3da6d49e
      由 Arnd Bergmann 提交于 
      We can now select clocksource drivers like ti-32k and CONFIG_OF
on ancient machines that still use gettimeoffset, and the combination
results in a link error.

arch/arm/kernel/built-in.o: In function `time_init':
(.init.text+0xc28): undefined reference to `clocksource_probe'

The reason for this is that the Makefile is hidden behind
CONFIG_ARCH_USES_GETTIMEOFFSET, but the Kconfig file is not, and
it has shown up just now because the ti-32k driver was added
and can be selected using COMPILE_TEST on all platforms.

This patch hides the Kconfig menu in CONFIG_ARCH_USES_GETTIMEOFFSET
as well.

Fixes: dfedaf10 "clocksource: ti-32k: make it depend on GENERIC_CLOCKSOURCE"
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Felipe Balbi <balbi@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/7579471.4N90fYPQOK@wuerfelSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      3da6d49e
  5. 17 10月, 2015 2 次提交
  7. 16 10月, 2015 1 次提交
  9. 01 10月, 2015 2 次提交
  11. 03 9月, 2015 1 次提交
  13. 10 8月, 2015 1 次提交
  15. 24 7月, 2015 1 次提交
  17. 24 6月, 2015 1 次提交
  19. 23 6月, 2015 1 次提交
  21. 22 6月, 2015 1 次提交
    • P
      clocksource: Increase dependencies of timer-stm32 to limit build wreckage · 1cb6c215
      由 Paul Gortmaker 提交于 
      This driver leaks out into arch/parisc builds that don't have
CONFIG_GENERIC_CLOCKEVENTS, leading to the following (truncated)
wreckage:

  CC      drivers/clocksource/timer-stm32.o
drivers/clocksource/timer-stm32.c:38:28: error: field 'evtdev' has incomplete type
drivers/clocksource/timer-stm32.c:44:19: warning: 'enum clock_event_mode' declared inside parameter list
drivers/clocksource/timer-stm32.c:44:19: warning: its scope is only this definition or declaration, which is probably not what you want
drivers/clocksource/timer-stm32.c:43:62: error: parameter 1 ('mode') has incomplete type
drivers/clocksource/timer-stm32.c:43:13: error: function declaration isn't a prototype
drivers/clocksource/timer-stm32.c: In function 'stm32_clock_event_set_mode':
drivers/clocksource/timer-stm32.c:47:3: error: type defaults to 'int' in declaration of '__mptr'
drivers/clocksource/timer-stm32.c:47:3: warning: initialization from incompatible pointer type
drivers/clocksource/timer-stm32.c:51:7: error: 'CLOCK_EVT_MODE_PERIODIC' undeclared (first use in this function)
drivers/clocksource/timer-stm32.c:51:7: note: each undeclared identifier is reported only once for each function it appears in
drivers/clocksource/timer-stm32.c:56:7: error: 'CLOCK_EVT_MODE_ONESHOT' undeclared (first use in this function)

Tighten up the dependencies to limit where it gets built by copying
the style of the Kconfig line for CLKSRC_EFM32 a few lines above.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: http://lkml.kernel.org/r/1434841352-24300-1-git-send-email-paul.gortmaker@windriver.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      1cb6c215
  23. 03 6月, 2015 1 次提交
  25. 02 6月, 2015 5 次提交
  27. 06 4月, 2015 1 次提交
  29. 01 4月, 2015 1 次提交
  31. 26 3月, 2015 1 次提交
  33. 17 3月, 2015 1 次提交
  35. 25 2月, 2015 1 次提交
  37. 29 1月, 2015 3 次提交
  39. 14 1月, 2015 1 次提交
  41. 09 1月, 2015 1 次提交
  43. 24 11月, 2014 2 次提交
  45. 18 11月, 2014 1 次提交
  47. 29 9月, 2014 1 次提交
  49. 15 9月, 2014 1 次提交
  51. 23 7月, 2014 1 次提交
    • D
      clocksource: exynos_mct: Only use 32-bits where possible · 3252a646
      由 Doug Anderson 提交于 
      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: NDoug Anderson <dianders@chromium.org>
Acked-by Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
      3252a646