linux-kernel - Correct ordering of phy_init and phy_power

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Message-ID: <6cd01e79-fdc0-3bd4-32b5-a85142533f8a@pengutronix.de>
Date:   Mon, 21 Dec 2020 00:06:39 +0100
From:   Ahmad Fatoum <a.fatoum@...gutronix.de>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>,
        Minas Harutyunyan <hminas@...opsys.com>,
        linux-usb@...r.kernel.org
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-usb@...r.kernel.org, Jules Maselbas <jmaselbas@...ray.eu>
Subject: Correct ordering of phy_init and phy_power_on

Hello,

I just noticed that USB controller drivers differ in the order in which they
do phy_init and phy_power_on. For example:

__dwc2_lowlevel_hw_enable():

	ret = phy_power_on(hsotg->phy);    
	if (ret == 0)                      
        	ret = phy_init(hsotg->phy);

dwc3_core_init():

	ret = dwc3_core_soft_reset(dwc); // internally does phy_init(dwc->usb2_generic_phy);
	/* [snip] */
	ret = phy_power_on(dwc->usb2_generic_phy);


My initial assumption has been init -> power_on, but at least the phy-stm32-usbphyc
(used with dwc2) is written with the assumption that exit -> power_off (and therefore
power_on -> init). If they are swapped, disabling fails.

So how was it meant to be?

Cheers,
Ahmad

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