Re: [PATCH v5] usb: common: usb-conn-gpio: Set last role to unknown before initial detection

[Prashanth K]

On 30-05-23 12:31 am, Greg Kroah-Hartman wrote:
> On Tue, May 30, 2023 at 12:00:15AM +0530, Prashanth K wrote:
> > On 28-05-23 05:03 pm, Greg Kroah-Hartman wrote:
> > > > > > diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
> > > > > > index e20874c..30bdb81 100644
> > > > > > --- a/drivers/usb/common/usb-conn-gpio.c
> > > > > > +++ b/drivers/usb/common/usb-conn-gpio.c
> > > > > > @@ -257,6 +257,9 @@ static int usb_conn_probe(struct platform_device *pdev)
> > > > > >     	platform_set_drvdata(pdev, info);
> > > > > >     	device_set_wakeup_capable(&pdev->dev, true);
> > > > > > +	/* Set last role to unknown before performing the initial detection */
> > > > > > +	info->last_role = USB_ROLE_UNKNOWN;
> > > > >
> > > > > Shouldn't last_role have already been set to 0?  If so, why not just
> > > > > have this enum value be 0?
> > > > Last role would be 0 during first detection, that's the problem here.
> > > > During initial detection, if the the new role is detected as USB_ROLE_NONE
> > > > (0), then we wouldn't call the set_role(). But it should send the current
> > > > role to gadget after the inital detection.
> > >
> > > So you are hoping that the old enum type is still assigned to 0?  That's
> > > brave, please make it explicit otherwise it's very hard to follow or
> > > ensure that this really will happen.  And most of all, document it so
> > > that that value remains 0 in the future, otherwise a list of enum types
> > > without explicit values are seen as if the values do not matter.
> > >
> > > thanks,
> > >
> > > greg k-h
> >
> > So I think it would be better to add USB_ROLE_UNKNOWN towards the end of
> > enum usb_role, so that we can avoid explicit declaration. Is that fine?
> >
> >   enum usb_role {
> >   	USB_ROLE_NONE,
> >   	USB_ROLE_HOST,
> >   	USB_ROLE_DEVICE,
> > +	USB_ROLE_UNKNOWN,
>
> Either is fine, be explicit, or not, just don't mix the two please.
>
> thanks,
>
> greg k-h

Thanks for the suggestion, will update it in next patch.

Regards,
Prashanth K