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From: Sascha Hauer <sha@pengutronix.de>
To: Ahmad Fatoum <ahmad@a3f.at>
Cc: barebox@lists.infradead.org, mgr@pengutronix.de
Subject: Re: [PATCH 1/2] fixup! usb: dwc2: Add support for optional usb phy
Date: Wed, 6 Jan 2021 11:05:43 +0100	[thread overview]
Message-ID: <20210106100543.GO19063@pengutronix.de> (raw)
In-Reply-To: <20201221003251.83042-2-ahmad@a3f.at>

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
> 
> 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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  reply	other threads:[~2021-01-06 10:05 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-21  0:32 [PATCH 0/2] usb: dwc2: gadget: fix stm32mp1 hang on barebox shutdown Ahmad Fatoum
2020-12-21  0:32 ` [PATCH 1/2] fixup! usb: dwc2: Add support for optional usb phy Ahmad Fatoum
2021-01-06 10:05   ` Sascha Hauer [this message]
2022-03-21 22:17     ` Michael Grzeschik
2022-03-22  5:35       ` Ahmad Fatoum
2022-03-22  8:19         ` Michael Grzeschik
2022-03-22  8:25           ` Ahmad Fatoum
2022-03-22  8:29             ` Michael Grzeschik
2022-03-22  9:23               ` Jules Maselbas
2020-12-21  0:32 ` [PATCH 2/2] regulator: stm32-pwr: don't propagate regulator turn-off to supply Ahmad Fatoum

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