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

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Date:   Mon, 10 Oct 2022 10:49:35 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pali Rohár <pali@...nel.org>
Cc:     "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 01-10-22, 01:45, Pali Rohár wrote:
> On Saturday 24 September 2022 10:31:27 Pali Rohár wrote:
> > On Saturday 24 September 2022 12:44:49 Vinod Koul wrote:
> > > On 21-09-22, 10:05, 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
> > > 
> > > update the log now?
> > 
> > What do you want to update?
> 
> Vinod, could you describe a bit more what is needed to update? Because
> this patch fixes regression - USB 3.0 support on Turris Mox board.

Sorry to have missed this...

Somehow I misunderstood that the USB 3.0 was not working and log needs
update... I will apply this once merge window closes

-- 
~Vinod