On Mon, Dec 21, 2020 at 01:32:50AM +0100, Ahmad Fatoum wrote:

Linux doesn't seem to enforce a fixed order between phy_init and
phy_power_on. The Linux dwc2 driver does power_on and then phy_init,
which is the inverse of what barebox is currently doing.

The PHYs normally used with dwc2 are written with this in mind.
For example, our stm32-usbphyc driver fails to disable:

  ERROR: stm32-usbphyc 5a006000.usbphyc@5a006000.of: PLL not reset
  ERROR: phy1: phy exit failed --> -5

Because Linux does exit -> power_off, but barebox does power_off ->
exit.

Issue was raised upstream:
https://lore.kernel.org/lkml/6cd01e79-fdc0-3bd4-32b5-a85142533f8a@pengutronix.de/T/#t (local)

Until this is settled, swap the order to follow what Linux does.
This is suboptimal, because it means controller drivers have different
order of the operations and that you can't combine arbitrary PHYs and
controllers, but it seems unlikely we will support combinations that
aren't supported by Linux in the first place anyway.

This is valuable information and I don't want it to be lost, so instead
of applying this as a fixup I rewrote the subject to:

usb: dwc2: swap order of phy_init and phy_power_on to what Linux does

and applied it as a separate patch.

Sascha

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