linux-kernel - Re: [PATCH] phy: marvell: phy-mvebu-a3700-comphy: Reset COMPHY registers before USB 3.0 power on

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Date:   Wed, 21 Sep 2022 14:57:22 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Shinichiro Kawasaki <shinichiro.kawasaki@....com>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] phy: marvell: phy-mvebu-a3700-comphy: Reset COMPHY
 registers before USB 3.0 power on

On Wednesday 21 September 2022 12:44:58 Shinichiro Kawasaki wrote:
> On Sep 21, 2022 / 08:05, Pali Rohár wrote:
> > On Wednesday 21 September 2022 05:03:01 Shinichiro Kawasaki wrote:
> > > On Sep 20, 2022 / 14:11, Pali Rohár wrote:
> > > > Turris MOX board with older ARM Trusted Firmware version v1.5 is not able
> > > > to detect any USB 3.0 device connected to USB-A port on Mox-A module after
> > > > commit 0a6fc70d76bd ("phy: marvell: phy-mvebu-a3700-comphy: Remove broken
> > > > reset support"). On the other hand USB 2.0 devices connected to the same
> > > > USB-A port are working fine.
> > > > 
> > > > It looks as if the older firmware configures COMPHY registers for USB 3.0
> > > > somehow incompatibly for kernel driver. Experiments show that resetting
> > > > COMPHY registers via setting SFT_RST auto-clearing bit in COMPHY_SFT_RESET
> > > > register fixes this issue.
> > > > 
> > > > Reset the COMPHY in mvebu_a3700_comphy_usb3_power_on() function as a first
> > > > step after selecting COMPHY lane and USB 3.0 function. With this change
> > > > Turris MOX board can successfully detect USB 3.0 devices again.
> > > > 
> > > > Before the above mentioned commit this reset was implemented in PHY reset
> > > > method, so this is the reason why there was no issue with older firmware
> > > > version then.
> > > > 
> > > > Fixes: 0a6fc70d76bd ("phy: marvell: phy-mvebu-a3700-comphy: Remove broken reset support")
> > > > Reported-by: Marek Behún <kabel@...nel.org>
> > > > Signed-off-by: Pali Rohár <pali@...nel.org>
> > > > ---
> > > > Shinichiro, could you please check that all USB functionality still
> > > > works correctly on your board?
> > > > ---
> > > 
> > > Sure. TL;DR, this patch works ok for my espressobin v7 board.
> > > 
> > > Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>
> > > 
> > > I prepared base kernel v5.19.10 applying the commit 0a6fc70d76bd. Regardless
> > > whether this fix patch for Turrix MOX board is applied or not, two USB ports on
> > > my esprssobin v7 board worked as expected. I confirmed it by using USB thumb
> > > drive. The drive was detected and its partition was mounted successfully using
> > > either of the two USB ports.
> > 
> > Thank you for testing! Anyway, please check that USB 3.0 device is
> > working fine. Because as I wrote in commit message, on Turris Mox was
> > USB 2.0 device working fine, but USB 3.0 not. And maybe check in system
> > (lsusb) that USB 3.0 device was really detected as USB 3.0 because USB
> > 3.0 devices have supported also fallback USB 2.0/1.x legacy mode.
> 
> Ah, I see. For that check, I connected my USB 3.1 drive to the USB 3.0 port of
> my espressobin, then checked 'lsusb -vt' and sysfs:
> 
> $ lsusb -vt
> /:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
>     ID 1d6b:0003 Linux Foundation 3.0 root hub
>     |__ Port 1: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
>         ID 0781:5583 SanDisk Corp. Ultra Fit
> /:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
>     ID 1d6b:0002 Linux Foundation 2.0 root hub
> /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=orion-ehci/1p, 480M
>     ID 1d6b:0002 Linux Foundation 2.0 root hub
> 
> $ cat /sys/bus/usb/devices/3-1/version 
>  3.00
> 
> USB3 port is listed under the Bus 03, "3.0" root hub. According to sysfs, its
> USB version is 3.00. I observed same outputs with and without the patch for
> Turris MOX board.
> 
> Are these good enough? If other check is needed, please let me know.

Perfect, that is enough! If USB 3.1 drive is detected and working then
everything is OK.