From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753057AbbCZOsD (ORCPT ); Thu, 26 Mar 2015 10:48:03 -0400 Received: from mga11.intel.com ([192.55.52.93]:10977 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752862AbbCZOr7 (ORCPT ); Thu, 26 Mar 2015 10:47:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,472,1422950400"; d="scan'208";a="686046529" Date: Thu, 26 Mar 2015 16:47:53 +0200 From: Mika Westerberg To: Octavian Purdila Cc: Linus Walleij , Lars-Peter Clausen , Robert Dolca , Robert Dolca , "linux-iio@vger.kernel.org" , Jonathan Cameron , "linux-kernel@vger.kernel.org" , Hartmut Knaack , Peter Meerwald , Denis CIOCCA Subject: Re: [PATCH] IIO: Adds ACPI support for ST gyroscopes Message-ID: <20150326144753.GO1878@lahna.fi.intel.com> References: <20150324150630.GP1878@lahna.fi.intel.com> <20150325094327.GW1878@lahna.fi.intel.com> <20150325122505.GX1878@lahna.fi.intel.com> <20150325132116.GY1878@lahna.fi.intel.com> <20150326101616.GD1878@lahna.fi.intel.com> <20150326140430.GM1878@lahna.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 26, 2015 at 04:37:39PM +0200, Octavian Purdila wrote: > On Thu, Mar 26, 2015 at 4:04 PM, Mika Westerberg > wrote: > > On Thu, Mar 26, 2015 at 02:04:35PM +0200, Octavian Purdila wrote: > >> On Thu, Mar 26, 2015 at 12:16 PM, Mika Westerberg > >> wrote: > >> > On Wed, Mar 25, 2015 at 11:12:16PM +0200, Octavian Purdila wrote: > >> >> On Wed, Mar 25, 2015 at 3:21 PM, Mika Westerberg > >> >> wrote: > >> >> > On Wed, Mar 25, 2015 at 02:25:05PM +0200, Mika Westerberg wrote: > >> >> >> I think we can do the same for ACPI GpioInts so that we introduce > >> >> >> acpi_gpio_irq_get() that translates from GpioInt to Linux IRQ > >> >> >> numberspace. Then we can do something like below in I2C core: > >> >> >> > >> >> >> if (client->irq <= 0) { > >> >> >> int irq = -ENOENT; > >> >> >> > >> >> >> if (dev->of_node) > >> >> >> irq = of_irq_get(dev->of_node, 0); > >> >> >> else if (ACPI_COMPANION(dev)) > >> >> >> irq = acpi_gpio_irq_get(ACPI_COMPANION(dev), 0); > >> >> >> > >> >> >> if (irq == -EPROBE_DEFER) > >> >> >> return irq; > >> >> >> if (irq < 0) > >> >> >> irq = 0; > >> >> >> > >> >> >> client->irq = irq; > >> >> >> } > >> >> >> > >> >> >> Now it has the drawback that the first GpioInt will not be available to > >> >> >> the driver anymore (as a GPIO since it is locked) but if DT already does > >> >> >> the same we should be fine. > >> >> > > >> >> > Below patch should take care of this. > >> >> > > >> >> > >> >> One issue we noticed is that now the gpio request and set input > >> >> directions operations are not called anymore. Some gpio controller > >> >> drivers (dln2, adnp, lynx_point from quickly browsing the code) do not > >> >> explicitly enable the GPIO pin nor set direction to input when the > >> >> interrupt is enabled. Depending on hardware this may be an issue - it > >> >> is on dln2 for example. > >> >> > >> >> Should the gpio controllers enable and set to input in irq_enable, > >> >> irq_bus_sync_unlock, etc.? Or should this be done in gpiolib? > >> > > >> > Good question. > >> > > >> > In general I think that it is assumed that the boot firmware configures > >> > the pin upfront. However, we have seen too many times that it actually > >> > doesn't happen or it is configured wrong. > >> > > >> > Perhaps we could do this in GPIO core, for example in > >> > gpiochip_irq_reqres/gpiochip_irq_map or so. > >> > > >> > >> That sounds good to me. We tested your patch with the patch below and > >> we can now directly use client->irq: > >> > >> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > >> index 568aa2b..9865627 100644 > >> --- a/drivers/gpio/gpiolib.c > >> +++ b/drivers/gpio/gpiolib.c > >> @@ -511,6 +511,19 @@ static const struct irq_domain_ops gpiochip_domain_ops = { > >> static int gpiochip_irq_reqres(struct irq_data *d) > >> { > >> struct gpio_chip *chip = irq_data_get_irq_chip_data(d); > >> + int ret; > >> + > >> + ret = gpiod_request(&chip->desc[d->hwirq], "IRQ"); > >> + if (ret) { > >> + chip_err(chip, "unable to request %lu for IRQ\n", d->hwirq); > >> + return ret; > >> + } > > > > What if the driver has already requested the GPIO? > > > > Initially I implemented the above to take that into account, e.g. if > (test_and_set_bit(FLAG_REQUESTED, &desc->flags) ... > > But than I thought that we can't mess up with the GPIO anyway while > the interrupt is in use. That's right but then the above will fail also normal cases. For example if the driver gets the irq like: desc = devm_gpiod_get(dev, ..); gpiod_direction_input(desc); irq = gpiod_to_irq(desc); ret = request_irq(irq, ...) at this point we end up calling gpiochip_irq_reqres() which cannot request the GPIO again and fails. > One case I missed was if the user wants to read the GPIO while using > it as an interrupt which seems to be possible... While the GPIO is locked as IRQ it cannot be done as far as I can tell but you can work it around by calling free_irq() first. > > >> + > >> + ret = gpiod_direction_input(&chip->desc[d->hwirq]); > >> + if (ret) { > >> + chip_err(chip, "unable to set HW IRQ %lu as input\n", d->hwirq); > >> + return ret; > >> + } > >> > >> if (gpiochip_lock_as_irq(chip, d->hwirq)) { > >> chip_err(chip,