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From:   Tomer Maimon <tmaimon77@gmail.com>
Date:   Mon, 18 Jul 2022 17:29:32 +0300
Message-ID: <CAP6Zq1gFnLYspn5+dYbSSOicZibCTbF9Z8bmNV+_HDP3=nLp8A@mail.gmail.com>
Subject: Re: [PATCH v1 1/3] usb: host: npcm7xx: remove USB EHCI host reset sequence
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Avi Fishman <avifishman70@gmail.com>,
        Tali Perry <tali.perry1@gmail.com>,
        Joel Stanley <joel@jms.id.au>,
        Patrick Venture <venture@google.com>,
        Nancy Yuen <yuenn@google.com>,
        Benjamin Fair <benjaminfair@google.com>,
        gregkh <gregkh@linuxfoundation.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        Tony Lindgren <tony@atomide.com>,
        Felipe Balbi <felipe.balbi@linux.intel.com>,
        Juergen Gross <jgross@suse.com>,
        Lukas Bulwahn <lukas.bulwahn@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        OpenBMC Maillist <openbmc@lists.ozlabs.org>,
        USB list <linux-usb@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>
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Hi Arnd,

Thanks for your detailed explanation.

I will remove this modification in the next version.

On Mon, 18 Jul 2022 at 15:38, Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Mon, Jul 18, 2022 at 2:29 PM Tomer Maimon <tmaimon77@gmail.com> wrote:
> >
> >  config USB_EHCI_HCD_NPCM7XX
> >         tristate "Support for Nuvoton NPCM7XX on-chip EHCI USB controller"
> > -       depends on (USB_EHCI_HCD && ARCH_NPCM7XX) || COMPILE_TEST
> > +       depends on (USB_EHCI_HCD && ARCH_NPCM7XX && RESET_NPCM) || COMPILE_TEST
> >         default y if (USB_EHCI_HCD && ARCH_NPCM7XX)
> >         help
> >           Enables support for the on-chip EHCI controller on
>
> I would leave out this Kconfig change, there is really no need to enforce
> this specific dependency.  It is expected that a device driver has dependencies
> on several other subsystems (irqchip, reset, pinctrl, clock, ....) and will only
> work if the required drivers are also built for the same kernel.
>
> Also, forcing the USB driver to be a loadable module when the reset driver
> is a module (rather than built-in) does not guarantee that they are initialized
> in the correct order. If only the USB driver is built-in and the reset driver is
> a module, or both are loadable modules and USB gets loaded first, then
> the probe() function should notice this and return -EPROBE_DEFER so
> it will be retried after the reset driver is successfully loaded.
>
>         Arnd

Best regards,

Tomer