Re: [Patch V3 03/18] phy: tegra: xusb: Add usb-role-switch support

[Nagarjuna Kristam]

On 28-01-2020 23:02, Thierry Reding wrote:
> On Mon, Dec 30, 2019 at 04:39:40PM +0530, Nagarjuna Kristam wrote:
> > If usb-role-switch property is present in USB 2 port, register
> > usb-role-switch to receive usb role changes.
> >
> > Signed-off-by: Nagarjuna Kristam<nkristam@xxxxxxxxxx>
> > ---
> > V3:
> >   - Driver aborts if usb-role-switch is not added in dt forotg/peripheral
> >     roles.
> >   - Added role name strings instead of enum values in debug prints.
> >   - Updated arguments and variable allignments as per Thierry inputs.
> > ---
> > V2:
> >   - Removed dev_set_drvdata for port->dev.
> >   - Added of_platform_depopulate during error handling and driver removal.
> > ---
> >   drivers/phy/tegra/Kconfig |  1 +
> >   drivers/phy/tegra/xusb.c  | 57 +++++++++++++++++++++++++++++++++++++++++++++++
> >   drivers/phy/tegra/xusb.h  |  3 +++
> >   3 files changed, 61 insertions(+)
> >
> > diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
> > index f9817c3..df07c4d 100644
> > --- a/drivers/phy/tegra/Kconfig
> > +++ b/drivers/phy/tegra/Kconfig
> > @@ -2,6 +2,7 @@
> >   config PHY_TEGRA_XUSB
> >   	tristate "NVIDIA Tegra XUSB pad controller driver"
> >   	depends on ARCH_TEGRA
> > +	select USB_CONN_GPIO
> >   	help
> >   	  Choose this option if you have an NVIDIA Tegra SoC.
> >   
> > diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c
> > index f98ec39..11ea9b5 100644
> > --- a/drivers/phy/tegra/xusb.c
> > +++ b/drivers/phy/tegra/xusb.c
> > @@ -523,6 +523,7 @@ static int tegra_xusb_port_init(struct tegra_xusb_port *port,
> >   	port->dev.type = &tegra_xusb_port_type;
> >   	port->dev.of_node = of_node_get(np);
> >   	port->dev.parent = padctl->dev;
> > +	port->dev.driver = padctl->dev->driver;
> This looks wrong. I don't think driver's are supposed to set this
> because it basically means that the device is being attached to the
> driver, but in this case it doesn't get probed by the driver and in
> fact the ports don't match the pad controller, so they can't really
> be driven by the same driver.
>
> Is there any particular reason why you need this?
>
> Thierry

Yes, port->dev.driver->owner is accessed in USB role switch driver in 
API usb_role_switch_get. If driver param is not updated, it causes NULL 
pointer exception. Based on your inputs, since this assignment is not 
supposed to used, I believe option available is to create a new 
device_driver structure and assign the same here.
Please share your thoughts.

- Nagarjuna