Hi Simon-san,
> From: Simon Horman, Sent: Tuesday, May 15, 2018 5:04 PM
>
> On Tue, May 15, 2018 at 08:02:00AM +0000, Yoshihiro Shimoda wrote:
> > Hi Simon-san,
> >
> > Thank you for your review!
> >
> > > From: Simon Horman, Sent: Tuesday, May 15, 2018 4:54 PM
> > > On Mon, May 14, 2018 at 06:15:59PM +0900, Yoshihiro Shimoda wrote:
> > <snip>
> > > > static void usb3_set_mode(struct renesas_usb3 *usb3, bool host)
> > > > {
> > > > - _usb3_set_mode(usb3, host);
> > > > + if (usb3->role_sw)
> > > > + usb_role_switch_set_role(usb3->role_sw, host ?
> > > > + USB_ROLE_HOST : USB_ROLE_DEVICE);
> > > > + else
> > > > + _usb3_set_mode(usb3, host);
> > > > }
> > > >
> > > > static void usb3_vbus_out(struct renesas_usb3 *usb3, bool enable)
> > > > @@ -672,8 +676,8 @@ static void usb3_mode_config(struct renesas_usb3 *usb3, bool host, bool a_dev)
> > > > {
> > > > unsigned long flags;
> > > >
> > > > - spin_lock_irqsave(&usb3->lock, flags);
> > > > usb3_set_mode(usb3, host);
> > > > + spin_lock_irqsave(&usb3->lock, flags);
> > >
> > > Hi Shimoda-san,
> > >
> > > could you clarify why moving this lock is safe?
> >
> > The usb3_set_mode() is possible to call usb_role_switch_set_role() API
> > and usb_role_switch_set_role() calls mutex_lock().
> > So, this moving this lock (especially avoiding irqsave) needs.
>
> Thanks, that make sense.
>
> But usb3_set_mode() may also call _usb3_set_mode().
> It is safe to call _usb3_set_mode() without holding the lock?
Thank you for the pointed out. I am thinking it is possible to be
unsafe without holding the lock. So, I'd like to improve this patch somehow
(for example: Add new usb role switch APIs without mutex).
Best regards,
Yoshihiro Shimoda
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