Hi, I would like to hear some comments about idea of scaling MMC clock frequency. The basic idea is to lower the clock when device is completely idle or not busy enough. The patchset adds MMC card as a devfreq device and uses simple_ondemand as governor. In idle this gave benefits (less energy consumed during idle): 1. Trats2 (Exynos4412): 2.6% 2. Rinato (Exynos3250): 1% but (especially on Rinato) it had impact on performance (probably because ondemand triggering a little to late). What is interesting manually changing the clock (without this patchset) gave slightly bigger benefits. Maybe the devfreq introduces noticeable overhead? Comments are welcomed. Maybe on other platforms this has bigger impact? Best regards, Krzysztof Krzysztof Kozlowski (3): mmc: Add dynamic frequency scaling ARM: dts: Specify MSHC realistic clocks and use frequency scaling ARM: dts: Use frequency scaling for MSHC Documentation/devicetree/bindings/mmc/mmc.txt | 2 + arch/arm/boot/dts/exynos3250-rinato.dts | 1 + arch/arm/boot/dts/exynos4412-trats2.dts | 4 +- drivers/mmc/card/block.c | 247 ++++++++++++++++++++++++++ drivers/mmc/core/Kconfig | 16 ++ drivers/mmc/core/core.h | 1 - drivers/mmc/core/host.c | 2 + include/linux/mmc/card.h | 8 + include/linux/mmc/host.h | 3 + 9 files changed, 282 insertions(+), 2 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
