Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754757Ab3HXONV (ORCPT ); Sat, 24 Aug 2013 10:13:21 -0400 Received: from mail-ea0-f169.google.com ([209.85.215.169]:38735 "EHLO mail-ea0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754296Ab3HXONS (ORCPT ); Sat, 24 Aug 2013 10:13:18 -0400 From: Tomasz Figa To: Laurent Pinchart Cc: Laurent Pinchart , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Linus Walleij , swarren@wwwdotorg.org, ian.campbell@citrix.com, mark.rutland@arm.com, pawel.moll@arm.com, galak@codeaurora.org, rob.herring@calxeda.com Subject: Re: [PATCH v2 3/3] gpio: pcf857x: Add OF support Date: Sat, 24 Aug 2013 16:13:11 +0200 Message-ID: <2417846.CRj8QejgZy@flatron> User-Agent: KMail/4.11 (Linux/3.10.9-gentoo; KDE/4.11.0; x86_64; ; ) In-Reply-To: <1688346.YLZnUtEaXr@avalon> References: <1376953494-9684-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com> <5465986.lNHQvRvp7j@flatron> <1688346.YLZnUtEaXr@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6543 Lines: 175 On Saturday 24 of August 2013 02:54:07 Laurent Pinchart wrote: > Hi Tomasz, > > Thank you for the review. > > On Saturday 24 August 2013 02:41:59 Tomasz Figa wrote: > > On Tuesday 20 of August 2013 01:04:54 Laurent Pinchart wrote: > > > Add DT bindings for the pcf857x-compatible chips and parse the > > > device > > > tree node in the driver. > > > > > > Signed-off-by: Laurent Pinchart > > > --- > > > > > > .../devicetree/bindings/gpio/gpio-pcf857x.txt | 71 > > > +++++++++++++++++ drivers/gpio/gpio-pcf857x.c > > > | 57 ++++++++++++++--- 2 files changed, 119 insertions(+), 9 > > > deletions(-) > > > > > > create mode 100644 > > > > > > Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > > > > diff --git a/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt new file > > > mode > > > 100644 > > > index 0000000..df94462 > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > @@ -0,0 +1,71 @@ > > [snip] > > > > + - pins-initial-state: Bitmask that specifies the initial state of > > > + each pin. When a bit is set to zero, the corresponding pin will > > > be > > > + initialized to the input (pulled-up) state. When the bit is > > > set to + one, the pin will be initialized the the low-level > > > output state. If + the property is not specified all pins will > > > be initialized to the + input state. > > > > Hmm, do you actually need to know whether those pins are outputs or > > inputs before they get used for first time? I believe any driver > > using GPIO will call gpio_direction_{in,out}put() before it starts > > using the pin, which will initialize the pin to a known state. > > > > What I'd suggest is making the driver handle this by having a bit mask > > that marks states of pins as defined and flagging all pins as > > undefined by default. Then any call to gpio_direction_output() or > > _input() would mark it as defined and direction of the pin could be > > stored in internal driver structures. > > The problem is that all pins are controlled through a single I2C write. > Setting the direction of a pin will set the direction of all other pins. > I thus need to know what the initial settings are to avoid glitches. Oh, that's a funny hardware, isn't it? :) Well, I guess it can't be helped then. Sorry for the noise. > > > + The I/O expander can detect input state changes, and thus > > > optionally > > > + act as an interrupt controller. When interrupts support is > > > desired > > > > I don't like this statement. Device tree should represent what the > > device allows you to do, not what you want the device to do. > > > > My opinion on this is that if the chip supports interrupts then it > > should always be an interrupt-controller (unless its interrupt pin is > > not wired on the board, but this still conforms to what I wrote > > above). > > I agree. What about the following text then ? > > The I/O expander can detect input state changes, and thus optionally act > as an interrupt controller. When the expander interrupt pin is > connected all the following properties must be set. For more > information please see the interrupt controller device tree bindings > documentation available at > Documentation/devicetree/bindings/interrupt-controller/interrupts.txt. Sounds good. > > > diff --git a/drivers/gpio/gpio-pcf857x.c > > > b/drivers/gpio/gpio-pcf857x.c > > > index 070e81f..50a90f1 100644 > > > --- a/drivers/gpio/gpio-pcf857x.c > > > +++ b/drivers/gpio/gpio-pcf857x.c > > [snip] > > > > @@ -50,6 +52,27 @@ static const struct i2c_device_id pcf857x_id[] = > > > { > > > > > > }; > > > MODULE_DEVICE_TABLE(i2c, pcf857x_id); > > > > > > +#ifdef CONFIG_OF > > > +static const struct of_device_id pcf857x_of_table[] = { > > > + { .compatible = "nxp,pcf8574", .data = (void *)8 }, > > > + { .compatible = "nxp,pcf8574a", .data = (void *)8 }, > > > + { .compatible = "nxp,pca8574", .data = (void *)8 }, > > > + { .compatible = "nxp,pca9670", .data = (void *)8 }, > > > + { .compatible = "nxp,pca9672", .data = (void *)8 }, > > > + { .compatible = "nxp,pca9674", .data = (void *)8 }, > > > + { .compatible = "nxp,pcf8575", .data = (void *)16 }, > > > + { .compatible = "nxp,pca8575", .data = (void *)16 }, > > > + { .compatible = "nxp,pca9671", .data = (void *)16 }, > > > + { .compatible = "nxp,pca9673", .data = (void *)16 }, > > > + { .compatible = "nxp,pca9675", .data = (void *)16 }, > > > + { .compatible = "maxim,max7328", .data = (void *)8 }, > > > + { .compatible = "maxim,max7329", .data = (void *)8 }, > > > + { .compatible = "ti,tca9554", .data = (void *)8 }, > > > + { } > > > +}; > > > +MODULE_DEVICE_TABLE(of, pcf857x_of_table); > > > +#endif > > > + > > > > > > /* > > > > > > * The pcf857x, pca857x, and pca967x chips only expose one read and > > > one > > > * write register. Writing a "one" bit (to match the reset state) > > > lets > > > > > > @@ -257,14 +280,29 @@ fail: > > > static int pcf857x_probe(struct i2c_client *client, > > > > > > const struct i2c_device_id *id) > > > > > > { > > > > > > - struct pcf857x_platform_data *pdata; > > > + struct pcf857x_platform_data *pdata = client- >dev.platform_data; > > > + struct device_node *np = client->dev.of_node; > > > > > > struct pcf857x *gpio; > > > > > > + unsigned int n_latch = 0; > > > + unsigned int ngpio; > > > > > > int status; > > > > > > - pdata = client->dev.platform_data; > > > - if (!pdata) { > > > +#ifdef CONFIG_OF > > > + if (np) { > > > > Wouldn't if (IS_ENABLED(CONFIG_OF) && np) be sufficient here, without > > the #ifdef? You would have to move the match table out of the #ifdef > > in this case, though... > > That's the exact reason why I've used #ifdef CONFIG_OF here, I didn't > want to add the overhead of the pcf857x_of_table when CONFIG_OF isn't > defined. I'm not sure if I remember correctly, but I think there was something said in one of discussions some time ago, that we should be moving away from ifdef'ing such things, in favour of just having them compiled unconditionally. [Adding DT maintainers on Cc for more opinions.] Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/