linux-kernel - Re: [PATCH v2 10/10] usb: chipidea: tegra: Add USB_TEGRA

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Message-ID: <20191230210259.GD24135@qmqm.qmqm.pl>
Date:   Mon, 30 Dec 2019 22:02:59 +0100
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Peter Chen <peter.chen@....com>, Rob Herring <robh-dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Felipe Balbi <balbi@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 10/10] usb: chipidea: tegra: Add USB_TEGRA_PHY module
 to driver's dependencies

On Tue, Dec 24, 2019 at 07:21:05AM +0300, Dmitry Osipenko wrote:
> 24.12.2019 00:32, Michał Mirosław пишет:
> > On Fri, Dec 20, 2019 at 07:31:08AM +0300, Dmitry Osipenko wrote:
> >> 20.12.2019 06:56, Peter Chen пишет:
> >>> On 19-12-20 04:52:38, Dmitry Osipenko wrote:
> > [...]
> >>>> --- a/drivers/usb/chipidea/ci_hdrc_tegra.c
> >>>> +++ b/drivers/usb/chipidea/ci_hdrc_tegra.c
> >>>> @@ -53,6 +53,12 @@ static int tegra_udc_probe(struct platform_device *pdev)
> >>>>  	struct tegra_udc *udc;
> >>>>  	int err;
> >>>>  
> >>>> +	if (IS_MODULE(CONFIG_USB_TEGRA_PHY)) {
> >>>> +		err = request_module("phy_tegra_usb");
> >>>> +		if (err)
> >>>> +			return err;
> >>>> +	}
> >>>> +
> >>>
> >>> Why you do this dependency, if this controller driver can't
> >>> get USB PHY, it should return error. What's the return value
> >>> after calling below:
> >>>
> >>> 	udc->phy = devm_usb_get_phy_by_phandle(&pdev->dev, "nvidia,phy", 0);
> >>
> >> It returns -EPROBE_DEFER when phy_tegra_usb isn't loaded.
> > 
> > How are other driver modules autoloaded? Isn't there an appropriate
> > MODALIAS or MODULE_DEVICE_TABLE in there?
> 
> Hello Michał,
> 
> The phy_tegra_usb module is fine by itself, it's getting autoloaded.
> 
> The problem is that ci_hdrc_tegra module depends on the phy_tegra_usb
> module and thus the PHY module should be loaded before the CI module,
> otherwise CI driver fails with the EPROBE_DEFER.

Why, then, is CI driver not being probed again after PHY driver loads?
EPROBE_DEFER is what should cause driver core to re-probe a device after
other devices appear (PHY in this case).

Best Regards,
Michał Mirosław