linux-kernel - Re: [RFC PATCH v2 04/15] usb:cdns3: Driver initialization code.

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Message-ID: <CAL411-rzhH+y-b0-xze4-WmeVtey4bXt4Jc6TWYyfw6E8x-5Eg@mail.gmail.com>
Date:   Tue, 4 Dec 2018 15:11:40 +0800
From:   Peter Chen <hzpeterchen@...il.com>
To:     pawell@...ence.com
Cc:     devicetree@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, rogerq@...com,
        lkml <linux-kernel@...r.kernel.org>, adouglas@...ence.com,
        jbergsagel@...com, nsekhar@...com, nm@...com, sureshp@...ence.com,
        peter.chen@....com, pjez@...ence.com, kurahul@...ence.com
Subject: Re: [RFC PATCH v2 04/15] usb:cdns3: Driver initialization code.

On Mon, Dec 3, 2018 at 4:34 AM Pawel Laszczak <pawell@...ence.com> wrote:
>
> >>
> >> Patch adds core.c and core.h file that implements initialization
> >> of platform driver and adds function responsible for selecting,
> >> switching and running appropriate Device/Host mode.
> >>
> >> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> >> ---
> >>  drivers/usb/cdns3/Makefile |   2 +
> >>  drivers/usb/cdns3/core.c   | 413 +++++++++++++++++++++++++++++++++++++
> >>  drivers/usb/cdns3/core.h   | 100 +++++++++
> >>  3 files changed, 515 insertions(+)
> >>  create mode 100644 drivers/usb/cdns3/core.c
> >>  create mode 100644 drivers/usb/cdns3/core.h
> >>
> >> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
> >> index dcdd62003c6a..02d25b23c5d3 100644
> >> --- a/drivers/usb/cdns3/Makefile
> >> +++ b/drivers/usb/cdns3/Makefile
> >> @@ -1,3 +1,5 @@
> >> +obj-$(CONFIG_USB_CDNS3)                        += cdns3.o
> >>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)       += cdns3-pci.o
> >>
> >> +cdns3-y                                        := core.o
> >>  cdns3-pci-y                            := cdns3-pci-wrap.o
> >> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> >> new file mode 100644
> >> index 000000000000..f9055d4da67f
> >> --- /dev/null
> >> +++ b/drivers/usb/cdns3/core.c
> >> @@ -0,0 +1,413 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Cadence USBSS DRD Driver.
> >> + *
> >> + * Copyright (C) 2018 Cadence.
> >> + *
> >
> >Please add NXP copyright too.
>
> Ok, I don't know why I omitted this.
> I know that you are the main author of this file
> Sorry for that.
>
> One additional question. What year I should add in Copyright for NXP?.
> The original year 2017 or I should modified all to 2018.
>
Please use below copyright, thanks.

Copyright 2017-2018 NXP



> >> +       mutex_init(&cdns->mutex);
> >> +
> >> +       cdns->phy = devm_phy_get(dev, "cdns3,usbphy");
> >> +       if (IS_ERR(cdns->phy)) {
> >> +               dev_info(dev, "no generic phy found\n");
> >> +               cdns->phy = NULL;
> >> +               /*
> >> +                * fall through here!
> >> +                * if no generic phy found, phy init
> >> +                * should be done under boot!
> >> +                */
> >
> >If the phy driver is defer-probed, it will be here, it is not an error.
> >I think you could have a generic phy driver or usb generic phy driver
> >(drivers/usb/phy/phy-generic.c) even you don't need any operations for
> >PHY. It will be easy for other platforms.
>
> Yes, Roger ask me to modify this fragment. In next version it will look like:
>         cdns->phy = devm_phy_get(dev, "cdns3,usbphy");
>         if (IS_ERR(cdns->phy)) {
>                 ret = PTR_ERR(cdns->phy);
>                 if (ret == -ENOSYS || ret == -ENODEV) {
>                         cdns->phy = NULL;
>                 } else if (ret == -EPROBE_DEFER) {
>                         return ret;
>                 } else {
>                         dev_err(dev, "no phy found\n");
>                         goto err0;
>                 }
>         }
>
>         phy_init(cdns->phy);
>
> We are going to use phy driver. I don't know if it correct.
> I don't have experience in this filed.
> We need phy initialization but I don't have testing platform now.
> In most usb drivers I see that there are used usb phy driverd instead phy dirverd.
>

At my CDNS3 platform, there are some USB PHY initialization for register setting
and clock enable. You could add generic PHY driver under: drivers/phy/cadence/.

Above PHY initialization code is OK for me.


> >> +static void __exit cdns3_driver_platform_unregister(void)
> >> +{
> >> +       platform_driver_unregister(&cdns3_driver);
> >> +}
> >> +module_exit(cdns3_driver_platform_unregister);
> >> +
> >> +MODULE_ALIAS("platform:cdns3");
> >> +MODULE_AUTHOR("Pawel Laszczak <pawell@...ence.com>");
> >> +MODULE_LICENSE("GPL v2");
> >> +MODULE_DESCRIPTION("Cadence USB3 DRD Controller Driver");
> >> diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
> >> new file mode 100644
> >> index 000000000000..7c8204fe4d3d
> >> --- /dev/null
> >> +++ b/drivers/usb/cdns3/core.h
> >> @@ -0,0 +1,100 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +/*
> >> + * Cadence USBSS DRD Driver.
> >> + *
> >
> >Header file
> I don't understand. What is wrong ?
> >

The comment for this file

Cadence USBSS DRD Core Header File

Peter