On Fri, Jul 13, 2018 at 03:22:58PM +0530, Sayali Lokhande wrote: > This change adds the use of devfreq to MMC. > Both eMMC and SD card will use it. > For some workloads, such as video playback, it isn't > necessary for these cards to run at high speed. > Running at lower frequency, for example 52MHz, in such > cases can still meet the deadlines for data transfers. > Scaling down the clock frequency dynamically has power > savings not only because the bus is running at lower frequency > but also has an advantage of scaling down the system core > voltage, if supported. > Provide an ondemand clock scaling support similar to the > cpufreq ondemand governor having two thresholds, > up_threshold and down_threshold to decide whether to > increase the frequency or scale it down respectively. > The sampling interval is in the order of milliseconds. > If sampling interval is too low, frequent switching of > frequencies can lead to high power consumption and if > sampling interval is too high, the clock scaling logic > would take long time to realize that the underlying > hardware (controller and card) is busy and scale up > the clocks. > > Signed-off-by: Talel Shenhar <tatias@xxxxxxxxxxxxxx> > Signed-off-by: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx> > --- > .../devicetree/bindings/mmc/sdhci-msm.txt | 10 + > drivers/mmc/core/core.c | 560 +++++++++++++++++++++ > drivers/mmc/core/core.h | 7 + > drivers/mmc/core/debugfs.c | 46 ++ > drivers/mmc/core/host.c | 8 + > drivers/mmc/core/mmc.c | 200 +++++++- > drivers/mmc/core/sd.c | 72 ++- > drivers/mmc/host/sdhci-msm.c | 37 ++ > drivers/mmc/host/sdhci-pltfm.c | 11 + > drivers/mmc/host/sdhci.c | 27 + > drivers/mmc/host/sdhci.h | 8 + > include/linux/mmc/card.h | 5 + > include/linux/mmc/host.h | 70 +++ > 13 files changed, 1059 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt > index 502b3b8..bd8470a 100644 > --- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt > +++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt > @@ -26,6 +26,15 @@ Required properties: > "cal" - reference clock for RCLK delay calibration (optional) > "sleep" - sleep clock for RCLK delay calibration (optional) > > +Optional Properties: > +- qcom,devfreq,freq-table - specifies supported frequencies for clock scaling. > + Clock scaling logic shall toggle between these frequencies based > + on card load. In case the defined frequencies are over or below > + the supported card frequencies, they will be overridden > + during card init. In case this entry is not supplied, > + the driver will construct one based on the card > + supported max and min frequencies. > + The frequencies must be ordered from lowest to highest. This should be a common binding in which case will just a list of frequencies be sufficient. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
