On 02/02/2023 15:59, Ulf Hansson wrote: > On Tue, 31 Jan 2023 at 17:57, Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> On 30/01/2023 07:54, Hermes Zhang wrote: >>> On 2023/1/29 18:58, Krzysztof Kozlowski wrote: >>>> On 29/01/2023 03:36, Hermes Zhang wrote: >>>>> This commit add a new property: cap-aggressive-pm to enable the >>>> Do not use "This commit/patch". >>>> https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95 >>> >>> Done >>> >>>>> MMC_CAP_AGGRESSIVE_PM feature for (e)MMC/SD power saving. >>>> Why this is a property suitable for DT? IOW, why this isn't enabled always? >>> >>> This property will benfit for the power consumption, but it also may >>> degradation in performance as it will prevent the >>> >>> the card from executing internal house-keeping operations in idle mode. >>> So it's better to config it from DT. >> >> Why? DT is not for policy. How you described it, this is policy or >> system tuning choice thus the job for Linux (OS), not for DT. So I will >> repeat - why this property fits the purpose of DT (describe the hardware). >> > > I guess the HW perspective here, is that it might not fit all > platforms nor the actual eMMC/SD card to support this feature. > However, it still seems like a policy rather than a strict HW > constraint. > > Perhaps there is a way to figure out in the host driver, to > conditionally set the MMC_CAP_AGGRESSIVE_PM for the host, when needed > instead? What also worries me is that there is no user of this property: no DTS, no driver, so it is tricky to deduct out when it is applicable. Anyway things which might be obvious for the submitter, might not be for the reviewer, thus I would really like to see justification why different boards (or memories) need this property. Best regards, Krzysztof
