Re: [PATCH RFC 0/7] Add devfreq based clock scaling support for mmc

Ulf Hansson
2018-07-16T10:11:43Z

On 13 July 2018 at 11:52, Sayali Lokhande <sayalil@codeaurora.org> wrote:
> This change adds the use of devfreq based clock scaling to MMC.
> Both eMMC and SD card can 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,
> 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 as per load.
>
> Sahitya Tummala (1):
> devfreq: Add new flag to do simple clock scaling
>
> Sayali Lokhande (6):
> mmc: core: devfreq: Add devfreq based clock scaling support
> mmc: core: Add sysfs entries for dynamic control of clock scaling
> mmc: core: add support for devfreq suspend/resume
> mmc: sdhci-msm: Kconfig: select devfreq ondemand for sdhci-msm
> mmc: sdhci-msm: Enable clock scaling property
> mmc: core: Add a debugfs entry to set max clock rate
>
> .../devicetree/bindings/mmc/sdhci-msm.txt | 10 +
> Documentation/mmc/mmc-dev-attrs.txt | 38 ++
> drivers/devfreq/governor_simpleondemand.c | 25 +-
> drivers/mmc/core/core.c | 672 +++++++++++++++++++++
> drivers/mmc/core/core.h | 9 +
> drivers/mmc/core/debugfs.c | 90 +++
> drivers/mmc/core/host.c | 163 ++++-
> drivers/mmc/core/mmc.c | 227 ++++++-
> drivers/mmc/core/sd.c | 85 ++-
> drivers/mmc/host/Kconfig | 2 +
> drivers/mmc/host/sdhci-msm.c | 38 ++
> drivers/mmc/host/sdhci-pltfm.c | 11 +
> drivers/mmc/host/sdhci.c | 27 +
> drivers/mmc/host/sdhci.h | 8 +
> include/linux/devfreq.h | 4 +
> include/linux/mmc/card.h | 5 +
> include/linux/mmc/host.h | 70 +++
> 17 files changed, 1475 insertions(+), 9 deletions(-)
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

Thanks for you patchse! Just wanted to let you know that I am current
in holiday mode, so I needs some more time to review this properly.
Apologize for the inconvenience.

Kind regards
Uffe