Re: [PATCH v2 00/15] UFS: Add OPP and interconnect support

From: Bart Van Assche
Date: Thu Jul 20 2023 - 12:44:57 EST


On 7/19/23 22:40, Manivannan Sadhasivam wrote:
This series adds OPP (Operating Points) support to UFSHCD driver and
interconnect support to Qcom UFS driver.

Motivation behind adding OPP support is to scale both clocks as well as
regulators/performance state dynamically. Currently, UFSHCD just scales
clock frequency during runtime with the help of "freq-table-hz" property
defined in devicetree. With the addition of OPP tables in devicetree (as
done for Qcom SDM845 and SM8250 SoCs in this series) UFSHCD can now scale
both clocks and performance state of power domain which helps in power
saving.

For the addition of OPP support to UFSHCD, there are changes required to
the OPP framework and devfreq drivers which are also added in this series.

Finally, interconnect support is added to Qcom UFS driver for scaling the
interconnect path dynamically. This is required to avoid boot crash in
recent SoCs and also to save power during runtime. More information is
available in patch 13/13.

How much power can OPP save? I'm asking this since I'm wondering whether
the power saved by OPP outweighs the complexity added by this patch series.

Thanks,

Bart.