From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH 3/5] gpio/omap: Add DT support to GPIO driver Date: Tue, 26 Feb 2013 17:45:15 -0600 Message-ID: <512D490B.70900@ti.com> References: <1329321854-24490-1-git-send-email-b-cousson@ti.com> <1329321854-24490-4-git-send-email-b-cousson@ti.com> <4F44FA56.7020000@gmail.com> <4F44FC37.2000701@ti.com> <4F452484.5080503@gmail.com> <74CDBE0F657A3D45AFBB94109FB122FF17BD8BC6C1@HQMAIL01.nvidia.com> <4F47AD08.4030504@ti.com> <512D39DA.7020306@ti.com> <512D3AB1.1080202@wwwdotorg.org> <512D3EC2.6050408@ti.com> <512D3FE6.1010300@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <512D3FE6.1010300@wwwdotorg.org> Sender: linux-omap-owner@vger.kernel.org To: Stephen Warren Cc: Javier Martinez Canillas , Stephen Warren , Kevin Hilman , "devicetree-discuss@lists.ozlabs.org" , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linus Walleij , Grant Likely List-Id: devicetree@vger.kernel.org On 02/26/2013 05:06 PM, Stephen Warren wrote: > On 02/26/2013 04:01 PM, Jon Hunter wrote: >> >> On 02/26/2013 04:44 PM, Stephen Warren wrote: >>> On 02/26/2013 03:40 PM, Jon Hunter wrote: >>>> >>>> On 02/26/2013 04:01 AM, Javier Martinez Canillas wrote: >>>> >>>> [snip] >>>> >>>>> I was wondering if the level/edge settings for gpios is working on OMAP. >>>>> >>>>> I'm adding DT support for an SMSC911x ethernet chip connected to the >>>>> GPMC for an OMAP3 SoC based board. >>>>> >>>>> In the smsc911x driver probe function (smsc911x_drv_probe() in >>>>> drivers/net/ethernet/smsc/smsc911x.c), a call to request_irq() with >>>>> the flag IRQF_TRIGGER_LOW is needed because of the wiring on my board. >>>>> >>>>> Reading the gpio-omap.txt documentation it says that #interrupt-cells >>>>> should be <2> and that a value of 8 is "active low level-sensitive". >>>>> >>>>> So I tried this: >>>>> >>>>> &gpmc { >>>>> ethernet@5,0 { >>>>> pinctrl-names = "default"; >>>>> pinctrl-0 = <&smsc911x_pins>; >>>>> compatible = "smsc,lan9221", "smsc,lan9115"; >>>>> reg = <5 0 0xff>; /* CS5 */ >>>>> interrupt-parent = <&gpio6>; >>>>> interrupts = <16 8>; /* gpio line 176 */ >>>>> interrupt-names = "smsc911x irq"; >>>>> vmmc-supply = <&vddvario>; >>>>> vmmc_aux-supply = <&vdd33a>; >>>>> reg-io-width = <4>; >>>>> >>>>> smsc,save-mac-address; >>>>> }; >>>>> }; >>>> >>>> Are you requesting the gpio anywhere? If not then this is not going to >>>> work as-is. This was discussed fairly recently [1] and the conclusion >>>> was that the gpio needs to be requested before we can use as an interrupt. >>> >>> That seems wrong; the GPIO/IRQ driver should handle this internally. The >>> Ethernet driver shouldn't know/care whether the interrupt it's given is >>> some form of dedicated interrupt or a GPIO-based interrupt, and even if >>> it somehow did, there's no irq_to_gpio() any more, so the driver can't >>> tell which GPIO ID it should request, unless it's given yet another >>> property to represent this. >> >> I agree that ideally this should be handled internally. Did you read the >> discussion on the thread that I referenced [1]? If you have any thoughts >> we are open to ideas :-) >> >> Cheers >> Jon >> >> [1] http://comments.gmane.org/gmane.linux.ports.arm.omap/92192 > > Oh, when I clicked that link the first time, all I saw was the patch, > not any discussion. I guess it must have timed out finding the other > emails or something. Actually, I sent a slightly different link the 2nd time to ensure you saw the thread. So my fault ;-) > I disagree that the GPIO needs to be requested, and that a custom DT > property and associated code are needed for that; simply requesting the > IRQ should be enough to make everything work. > > In the Tegra GPIO IRQ driver for example, the irq_set_type irq_chip op > goes and configures the base GPIO HW to enable the pin as a GPIO, just > like gpio_request() would. I imagine the OMAP driver can do whatever > similar action it needs. Yes that is similar to what the patch in the thread was attempting to do, but this got shot down. One issue I see is that by not calling gpio_request, then potentially you could have someone request a gpio via gpio_request() and someone trying to use it as an interrupt source via request_irq(). Now obviously that represents a bug because there is only one physical gpio, but I gather it is something we need to protect against. Cheers Jon