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

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Date:   Wed, 5 Dec 2018 08:55:28 +0000
From:   Alan Douglas <adouglas@...ence.com>
To:     Pawel Laszczak <pawell@...ence.com>,
        Peter Chen <hzpeterchen@...il.com>
CC:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "rogerq@...com" <rogerq@...com>,
        lkml <linux-kernel@...r.kernel.org>,
        "jbergsagel@...com" <jbergsagel@...com>,
        "nsekhar@...com" <nsekhar@...com>, "nm@...com" <nm@...com>,
        Suresh Punnoose <sureshp@...ence.com>,
        "peter.chen@....com" <peter.chen@....com>,
        Pawel Jez <pjez@...ence.com>, Rahul Kumar <kurahul@...ence.com>
Subject: RE: [RFC PATCH v2 04/15] usb:cdns3: Driver initialization code.

Hi Peter,

On 05 December 2018 07:20, Pawel Laszczak wrote:
> Hi,
> 
> >> >>
> >> >> 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
> 
> I add this in all files  modified or created by you.
> >
> >
> >
> >> >> +       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.
> 
> It will be added as separate driver.
> I think that Allan Douglas working on it.
> I ask him to add you to -cc in patch for phy.
Patch series for the cadence Sierra generic PHY driver can be found here:
https://lore.kernel.org/patchwork/cover/1011486/

It can also be found in Kishon's linux-phy git tree at
    git://git.kernel.org/pub/scm/linux/kernel/git/kishon/linux-phy.git
in the 'next' branch.

It will be great if you are able to take a look at it.

Regards,
Alan