On 6/8/2021 5:40 AM, Ulf Hansson wrote: > On Wed, 2 Jun 2021 at 21:28, Al Cooper <alcooperx@xxxxxxxxx> wrote: >> >> Add support for the legacy Arasan sdhci controller on the BCM7211 and >> related SoC's. This includes adding a .shutdown callback to increase >> the power savings during S5. > > Please split this into two separate changes. > > May I also ask about the ->shutdown() callback and in relation to S5. > What makes the ->shutdown callback only being invoked for S5? It is not only called for S5 (entered via poweroff on a prompt) but also during kexec or reboot. The poweroff path is via: kernel_power_off() -> kernel_shutdown_prepare() -> device_shutdown() -> .shutdown() For kexec or reboot we do not really care about power savings since we are about to load a new image anyway, however for S5/poweroff we do care about quiescing the eMMC controller in a way that its clocks and the eMMC device can be put into low power mode since we will stay in that mode for seconds/hours/days until someone presses a button on their remote (or other wake-up sources). -- Florian
