linux-kernel - Re: [PATCH RFC] usb: dwc3: Remove dwc3 dependency on gadget.

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Date:	Fri, 11 Jan 2013 15:59:31 +0200
From:	Felipe Balbi <balbi@...com>
To:	Vivek Gautam <gautamvivek1987@...il.com>
CC:	<balbi@...com>, Vivek Gautam <gautam.vivek@...sung.com>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <gregkh@...uxfoundation.org>,
	Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH RFC] usb: dwc3: Remove dwc3 dependency on gadget.

Hi,

On Fri, Jan 11, 2013 at 07:13:55PM +0530, Vivek Gautam wrote:
> On Thu, Jan 10, 2013 at 6:32 PM, Felipe Balbi <balbi@...com> wrote:
> > Hi,
> >
> > On Mon, Dec 24, 2012 at 07:28:33PM +0530, Vivek Gautam wrote:
> >> DWC3 controller curretly depends on CONFIG_USB and CONFIG_USB_GADGET.
> >> Some hardware may like to use only host feature on dwc3.
> >> So, removing the dependency of USB_DWC3 on USB_GADGET
> >> and further modulating the dwc3 core to enable gadget features
> >> only with USB_GADGET.
> >>
> >> Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
> >> CC: Doug Anderson <dianders@...omium.org>
> >
> > right, right... Eventually we need to do it, but you're only making
> > gadget side optional. Host side should be optional too, but then you
> > need to make sure we don't build dwc3 without gadget and host.
> >
> 
> Yes, true we need to make host side also optional, build dwc3 only when
> either of host or gadget are built.

btw, make the default Dual-Role, if user/defconfig doesn't select
anything we want to build with all features.

> > Maybe make a mode selection for Host-only, Peripheral-only, Dual-Role
> > Device ??
> >
> 
> True this will be good idea to use modes: host only, gadget only or dual role.
> May be the platform glue layers can use them later to put the controller
> in a specific mode ?

probably not as that's likely to change from board to board.

> >>  int dwc3_gadget_init(struct dwc3 *dwc);
> >>  void dwc3_gadget_exit(struct dwc3 *dwc);
> >> +#else
> >> +static inline int dwc3_gadget_init(struct dwc3 *dwc)
> >> +{ return -EINVAL; }
> >> +static inline void dwc3_gadget_exit(struct dwc3 *dwc)
> >> +{ }
> >> +#endif
> >>
> >>  #endif /* __DRIVERS_USB_DWC3_CORE_H */
> >> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> >> index d4a30f1..553bbaa 100644
> >> --- a/drivers/usb/dwc3/debugfs.c
> >> +++ b/drivers/usb/dwc3/debugfs.c
> >> @@ -535,7 +535,8 @@ static ssize_t dwc3_testmode_write(struct file *file,
> >>               testmode = 0;
> >>
> >>       spin_lock_irqsave(&dwc->lock, flags);
> >> -     dwc3_gadget_set_test_mode(dwc, testmode);
> >> +     if (dwc3_gadget_set_test_mode(dwc, testmode))
> >> +             dev_dbg(dwc->dev, "host: Invalid request\n");
> >>       spin_unlock_irqrestore(&dwc->lock, flags);
> >>
> >>       return count;
> >
> > wrong, if you don't have gadget mode, you just don't create this file.
> >
> 
> dwc3-core makes call to dwc3_debugfs_init() invariably depending on DEBUG_FS.
> Will this not go ahead and create this file ?
> I think i am missing here something.  :-(

right, you can change dwc3_debugfs_init() to take into account the fact
that you're a gadget/drd or host-only.

In case of host only, you stil want regdump to be available :-)

-- 
balbi

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