From: Peter Chen <peter.chen@freescale.com>
To: David Cohen <david.a.cohen@linux.intel.com>
Cc: <myungjoo.ham@samsung.com>, <cw00.choi@samsung.com>,
<linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>,
<baolu.lu@linux.intel.com>
Subject: Re: [RFC/PATCH] extcon: otg_gpio: add driver for USB OTG port controlled by GPIO(s)
Date: Wed, 24 Dec 2014 11:08:52 +0800 [thread overview]
Message-ID: <20141224030835.GA31424@shlinux2> (raw)
In-Reply-To: <20141223194022.GA13792@psi-dev26.jf.intel.com>
On Tue, Dec 23, 2014 at 11:40:23AM -0800, David Cohen wrote:
> Hi Peter,
>
> Thanks for the review.
>
> On Tue, Dec 23, 2014 at 09:25:18AM +0800, Peter Chen wrote:
> > On Mon, Dec 22, 2014 at 02:43:37PM -0800, David Cohen wrote:
> > > Some platforms have an USB OTG port fully (or partially) controlled by
> > > GPIOs:
> > >
> > > (1) USB ID is connected directly to GPIO
> > >
> > > Optionally:
> > > (2) VBUS is enabled by a GPIO (when ID is grounded)
> > > (3) Platform has 2 USB controllers connected to same port: one for
> > > device and one for host role. D+/- are switched between phys
> > > by GPIO.
> >
> > Would you explain how it works? Choosing controller runtime?
>
> Both controllers are (indirectly) connected to the same micro B port.
> The D+/- goes from the port to a switch operated by a GPIO. From the
> switch, D+/- may go to Host controller's phy or Device controller's phy.
> Depends on the GPIO level.
>
Get it, why the design like that? If your controller supports both
roles, the software can do role switch by ID pin (through gpio in your
case).
> >
> > >
> > > As per initial version, this driver has the duty to control whether
> > > USB-Host cable is plugged in or not:
> >
> > You mean Micro-AB cable, right?
>
> > > +
> > > + vup->gpio_usb_mux = devm_gpiod_get_index(dev, "usb mux",
> > > + VUPORT_GPIO_USB_MUX);
> > > + if (IS_ERR(vup->gpio_usb_mux))
> > > + dev_info(dev, "cannot request USB USB MUX, skipping it.\n");
> >
> > Using dev_err
>
> That's not really an error, although the IS_ERR() suggests otherwise.
> The driver works well if a board doesn't need this mux (I'll add a
> comment to state that clear). IMHO either keep dev_info or use dev_dgb
> instead?
>
If that, dev_dbg may be suitable.
--
Best Regards,
Peter Chen
next prev parent reply other threads:[~2014-12-24 4:31 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-22 22:43 [RFC/PATCH] extcon: otg_gpio: add driver for USB OTG port controlled by GPIO(s) David Cohen
2014-12-23 1:25 ` Peter Chen
2014-12-23 19:40 ` David Cohen
2014-12-24 3:08 ` Peter Chen [this message]
2014-12-24 22:46 ` David Cohen
2014-12-23 13:10 ` Sergei Shtylyov
2014-12-23 19:57 ` David Cohen
2014-12-23 20:09 ` Sergei Shtylyov
2014-12-23 20:43 ` David Cohen
2014-12-24 0:29 ` Felipe Balbi
2014-12-24 22:43 ` David Cohen
2014-12-26 4:49 ` Felipe Balbi
2015-02-17 19:18 ` David Cohen
2015-02-17 19:25 ` Felipe Balbi
2015-02-17 19:35 ` David Cohen
2015-02-18 10:17 ` Mika Westerberg
2015-02-18 17:53 ` David Cohen
2015-01-08 19:23 ` Linus Walleij
2015-02-17 19:20 ` David Cohen
2015-02-19 19:59 ` [PATCH v2] " David Cohen
2015-02-19 22:39 ` Paul Bolle
2015-02-20 19:02 ` David Cohen
2015-02-20 19:09 ` Felipe Balbi
2015-02-20 19:18 ` David Cohen
2015-02-20 19:10 ` Paul Bolle
2015-02-20 19:18 ` David Cohen
2015-02-20 6:41 ` Robert Baldyga
2015-02-20 9:53 ` Linus Walleij
2015-02-20 19:17 ` David Cohen
2015-02-20 19:36 ` Felipe Balbi
2015-02-20 19:59 ` David Cohen
2015-02-20 20:00 ` Felipe Balbi
2015-02-20 20:40 ` David Cohen
2015-03-07 20:03 ` Linus Walleij
2015-02-24 19:18 ` David Cohen
2015-03-07 20:06 ` Linus Walleij
2015-03-09 16:16 ` Felipe Balbi
2015-03-09 19:10 ` David Cohen
2015-03-16 16:46 ` David Cohen
2015-03-16 16:46 ` David Cohen
2015-03-19 8:18 ` Linus Walleij
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