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

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Date:   Thu, 21 Jun 2018 11:08:07 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Andrey Smirnov <andrew.smirnov@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>,
        Peter Chen <peter.chen@....com>,
        USB list <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

Hi Andrey,

On Thu, Jun 21, 2018 at 9:47 AM, Andrey Smirnov
<andrew.smirnov@...il.com> wrote:

> 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.

I think we need to investigate this portsc register hang further.

> 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?

Yes, this can be improved, but this is not the cause of the issue .

gpio2 5 is passed as the USB PHY reset:

reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;

The default IOMUX setting after power on reset  is GPIO, so not an issue.

> 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.

Yes, it seems we need to revert the full patch and have a proper fix
in place that works for imx51 RDU, imx53-ppd and imx51 babbage.

The USB host 1 on imx51-babbage has been working since kernel 3.19 :-)

Thanks