From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Vorontsov Subject: Re: [PATCH 1/3] gpio: Add simple poweroff-gpio driver Date: Mon, 12 Nov 2012 11:17:08 -0800 Message-ID: <20121112191708.GA21040@lizard> References: <1352650891-18356-1-git-send-email-andrew@lunn.ch> <1352650891-18356-2-git-send-email-andrew@lunn.ch> <50A020C5.4070506@wwwdotorg.org> <20121112082546.GU22029@lunn.ch> <50A1212C.2080601@wwwdotorg.org> <20121112181947.GS24583@lunn.ch> <20121112184340.GA15643@lizard> <50A146E7.2040608@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <50A146E7.2040608-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Stephen Warren Cc: Andrew Lunn , Jason Cooper , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, jm-Pj/HzkgeCk7QXOPxS62xeg@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, gmbnomis-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Nov 12, 2012 at 11:58:47AM -0700, Stephen Warren wrote: [...] > >>>>> Unfortunately, not all GPIO bindings support active high/low flags in > >>>>> the GPIO specifier. As such, the flags there are basically useless. > >>>>> Other bindings (e.g. IIRC the fixed-regulator binding) have added a > >>>>> separate active-high property to indicate the GPIO polarity. This > >>>>> binding should probably follow suite. > > > > Should the gpio driver fix its bindings then?.. Polarity is a quite > > generic concept of a GPIO, and flags are there for a reason. I'd rather > > prefer having > > There is no "GPIO driver" to fix; each GPIO driver has its own bindings, > and unfortunately, some of the GPIO binding authors chose not to include > any flags cell in the GPIO specifier (e.g. Samsung ARM SoCs IIRC, but > there are probably more). They didn't read this? :) int of_gpio_simple_xlate(struct gpio_chip *gc, const struct of_phandle_args *gpiospec, u32 *flags) { /* * We're discouraging gpio_cells < 2, since that way you'll have to * write your own xlate function (that will have to retrive the GPIO * number and the flags from a single gpio cell -- this is possible, * but not recommended). */ if (gc->of_gpio_n_cells < 2) { WARN_ON(1); return -EINVAL; } They should have gotten the WARN_ON(). If not, if they do have the second cell, then they still can encode the flags. Just change the bindings in a backwards-compatible way. And even if they have just one cell, just as the comment above says, they still can add the polarity flag -- add it into the gpio number specifier. 0x0001 -- GPIO 1, 0x1001 -- GPIO 1, polarity inverted. In the gpio driver they have to mask the flags (by implementing their own xlate), of course. A few "broken" (but fixable) drivers/bindings is not the reason change the whole concept, or declare a long-standing API as 'not suitable for generic code'. At least it was meant exactly to be suitable for a generic code. :) Thanks, Anton.