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

[Bart Van Assche]

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.