On Tue, May 4, 2021 at 6:12 PM Ulf Hansson [off-list ref] wrote:

In SD spec v4.x the SD function extension registers were introduced. A
specific function register were added to let the card announce support for
optional features in regards to power management. The features that were
added are "Power Off Notification", "Power Down Mode" and "Power
Sustenance".

As a first step, let's read and parse this register for power management
during the SD card initialization and store the information about the
supported features in the struct mmc_card. In this way, we prepare for
subsequent changes to implement the complete support for the new features.

Signed-off-by: Ulf Hansson <redacted>

Looks to me like it will work just fine.
Reviewed-by: Linus Walleij <redacted>

Yours,
Linus Walleij