Re: [PATCH v5 06/13] mmc: arm_pl180: Power down card supplies at OS handoff

On Mon, Aug 24, 2026 at 3:30 PM Stephan Gerhold
<[email protected]> wrote:
> On Sun, Aug 23, 2026 at 10:39:25PM +0200, Linus Walleij wrote:

> > PL180 card supplies remain enabled after probing and while U-Boot is
> > running. They are no longer needed once control is handed to the operating
> > system.
> >
> > Mark the driver for removal during OS preparation and disable its VMMC and
> > VQMMC supplies from the remove callback.
> >
> > Signed-off-by: Linus Walleij <[email protected]>
>
> Is it worth briefly toggling the regulator off before Linux turns it on
> again? Linux will typically need to turn them on again later during
> boot, and even if not Linux should be able to deal with unused
> regulators. I'm not sure it's worth adding such cleanup to U-Boot.

For our specific Ux500 target it is true.

But this driver is used by a bunch of platforms including some
ARM reference designs, and also booting other operating systems
than Linux.

Something could EFI boot off one SD card, then have rootfs
on another one and the original boot card undefined in the
hardware description for example. Albeit that sounds a bit
stupid.

So I thought it'd be more clean to shut off the light on your way
out.

But it's not like I'm married to the patch.

Yours,
Linus Walleij