diff options
Diffstat (limited to 'ARM-Drop-fixed-200-Hz-timer-requirement-from-Samsung-platforms.patch')
| -rw-r--r-- | ARM-Drop-fixed-200-Hz-timer-requirement-from-Samsung-platforms.patch | 88 |
1 files changed, 0 insertions, 88 deletions
diff --git a/ARM-Drop-fixed-200-Hz-timer-requirement-from-Samsung-platforms.patch b/ARM-Drop-fixed-200-Hz-timer-requirement-from-Samsung-platforms.patch deleted file mode 100644 index bf389545b..000000000 --- a/ARM-Drop-fixed-200-Hz-timer-requirement-from-Samsung-platforms.patch +++ /dev/null @@ -1,88 +0,0 @@ -From patchwork Fri Nov 18 11:15:12 2016 -Content-Type: text/plain; charset="utf-8" -MIME-Version: 1.0 -Content-Transfer-Encoding: 7bit -Subject: [v3] ARM: Drop fixed 200 Hz timer requirement from Samsung platforms -From: Krzysztof Kozlowski <krzk@kernel.org> -X-Patchwork-Id: 9436225 -Message-Id: <1479467712-5218-1-git-send-email-krzk@kernel.org> -To: Russell King <linux@armlinux.org.uk>, Kukjin Kim <kgene@kernel.org>, - Krzysztof Kozlowski <krzk@kernel.org>, - Javier Martinez Canillas <javier@osg.samsung.com>, - linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, - linux-kernel@vger.kernel.org -Cc: Arnd Bergmann <arnd@arndb.de>, - Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>, - Tomasz Figa <tomasz.figa@gmail.com>, - Ben Dooks <ben.dooks@codethink.co.uk>, - Sylwester Nawrocki <s.nawrocki@samsung.com>, - Lee Jones <lee.jones@linaro.org>, - Marek Szyprowski <m.szyprowski@samsung.com> -Date: Fri, 18 Nov 2016 13:15:12 +0200 - -All Samsung platforms, including the Exynos, are selecting HZ_FIXED with -200 Hz. Unfortunately in case of multiplatform image this affects also -other platforms when Exynos is enabled. - -This looks like an very old legacy code, dating back to initial -upstreaming of S3C24xx. Probably it was required for s3c24xx timer -driver, which was removed in commit ad38bdd15d5b ("ARM: SAMSUNG: Remove -unused plat-samsung/time.c"). - -Since then, this fixed 200 Hz spread everywhere, including out-of-tree -Samsung kernels (SoC vendor's and Tizen's). I believe this choice -was rather an effect of coincidence instead of conscious choice. - -On S3C24xx, the PWM counter is only 16 bit wide, and with the -typical 12MHz input clock that overflows every 5.5ms. This works -with HZ=200 or higher but not with HZ=100 which needs a 10ms -interval between ticks. On Later chips (S3C64xx, S5P and EXYNOS), -the counter is 32 bits and does not have this problem. - -The new samsung_pwm_timer driver solves the problem by scaling the input -clock by a factor of 50 on S3C24xx, which makes it less accurate but -allows HZ=100 as well as CONFIG_NO_HZ with fewer wakeups. - -Few perf mem and sched tests on Odroid XU3 board (Exynos5422, 4x Cortex -A7, 4x Cortex A15) show no regressions when switching from 200 Hz to -other values. - -Reported-by: Lee Jones <lee.jones@linaro.org> -[Dropping of 200_HZ from S3C/S5P was suggested by Arnd] -Reported-by: Arnd Bergmann <arnd@arndb.de> -Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> -Cc: Kukjin Kim <kgene@kernel.org> -[Tested on Exynos5800] -Tested-by: Javier Martinez Canillas <javier@osg.samsung.com> -Acked-by: Kukjin Kim <kgene@kernel.org> -[Tested on S3C2440] -Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com> ---- - -Changes since v2: -1. Extend message. -2. Add Kukjin's ack. -3. Add Sylwester's tested-by. - -Changes since v1: -1. Add Javier's tested-by. -2. Drop HZ_FIXED also from ARCH_S5PV210 and ARCH_S3C24XX after Arnd - suggestions and analysis. ---- - arch/arm/Kconfig | 3 +-- - 1 file changed, 1 insertion(+), 2 deletions(-) - -diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig -index b5d529fdffab..ced2e08a9d08 100644 ---- a/arch/arm/Kconfig -+++ b/arch/arm/Kconfig -@@ -1496,8 +1496,7 @@ source kernel/Kconfig.preempt - - config HZ_FIXED - int -- default 200 if ARCH_EBSA110 || ARCH_S3C24XX || \ -- ARCH_S5PV210 || ARCH_EXYNOS4 -+ default 200 if ARCH_EBSA110 - default 128 if SOC_AT91RM9200 - default 0 - |