linux-kernel - Re: [PATCH] usb: chipidea: Fix ULPI on imx51

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Message-ID: <CAHQ1cqHxq+RM1nNHECY75Cojd_kxu1ERLe6+MhMLUa5kb10r8w@mail.gmail.com>
Date:   Thu, 21 Jun 2018 05:47:25 -0700
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>,
        Peter Chen <peter.chen@....com>, linux-usb@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Chris Healy <cphealy@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Sebastian Reichel <sebastian.reichel@...labora.co.uk>
Subject: Re: [PATCH] usb: chipidea: Fix ULPI on imx51

On Wed, Jun 20, 2018 at 3:22 PM Fabio Estevam <festevam@...il.com> wrote:
>
> On Wed, Jun 20, 2018 at 7:07 PM, Fabio Estevam <festevam@...il.com> wrote:
>
> > This patches causes a regression on a imx51-babbage running 4.18-rc1:
> > I get a kernel hang.
> >
> > If I revert it on top of 4.18-rc1, then it boots fine and USB host is
> > functional.
> >
> > I understand this patch fixes a kernel hang for you, so which commit
> > is responsible for the hang you observe?
> >

I never assumed it was a regression and that USB worked on RDU1 board
before, so I never tried to see if this was a regression. I can only
tell you that it hangs as soon as any PORTSC registers are accessed.

> > It seems this commit fixes a hang for you and causes another hang for me :-)
> >
> > Any ideas?
>

RDU1 design is based heavily on Babbage board, moreso USB1/ULPI
portion of it is an exact copy (it does use different GPIO for PHY
reset, but that's irrelevant), so I am surprised that it breaks in
your case.

However looking at imx51-babbage.dts, I am suspicious of it's USB1
setup. There we have usbh1phy node that references <&gpio2 5
GPIO_ACTIVE_LOW> as reset, but corresponding pinmux, pinctrl_usbh1reg,
is not being used anywhere. Cold that be that the problem you are
seeing is due to USB PHY not being properly reset?

> I am able to boot again if I skip passing the CI_HDRC_OVERRIDE_PHY_CONTROL flag:
>

Yeah, IMHO if you are dropping that flag, you may as well revert the
whole patch :-). The path that make the kernel hang in my case would
be taken if that flag is dropped.

Thanks,
Andrey Smirnov