From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v2] gpiolib: return -ENOENT if no GPIO mapping exists Date: Tue, 10 Dec 2013 17:28:11 +0200 Message-ID: <1386689291.1871.169.camel@smile> References: <1386686247-24592-1-git-send-email-acourbot@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga01.intel.com ([192.55.52.88]:38015 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752147Ab3LJP3E (ORCPT ); Tue, 10 Dec 2013 10:29:04 -0500 In-Reply-To: <1386686247-24592-1-git-send-email-acourbot@nvidia.com> Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Alexandre Courbot Cc: Linus Walleij , Mika Westerberg , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, 2013-12-10 at 23:37 +0900, Alexandre Courbot wrote: > Some devices drivers make use of optional GPIO parameters. For such > drivers, it is important to discriminate between the case where no > GPIO mapping has been defined for the function they are requesting, and > the case where a mapping exists but an error occured while resolving it > or when acquiring the GPIO. > > This patch changes the family of gpiod_get() functions such that they > will return -ENOENT if and only if no GPIO mapping is defined for the > requested function. Other error codes are used when an actual error > occured during the GPIO resolution. > One minor comment below. Independently on that: Reviewed-by: Andy Shevchenko > Signed-off-by: Alexandre Courbot > --- > Changes since v1: > - Rebase on top of Linus' devel tree > - Fixed error reporting as suggested by Andy > --- > Documentation/gpio/consumer.txt | 6 +++++- > drivers/gpio/gpiolib.c | 33 ++++++++++++++++----------------- > 2 files changed, 21 insertions(+), 18 deletions(-) > > diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt > index 07c74a3..e42f77d 100644 > --- a/Documentation/gpio/consumer.txt > +++ b/Documentation/gpio/consumer.txt > @@ -38,7 +38,11 @@ device that displays digits), an additional index argument can be specified: > const char *con_id, unsigned int idx) > > Both functions return either a valid GPIO descriptor, or an error code checkable > -with IS_ERR(). They will never return a NULL pointer. > +with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned > +if and only if no GPIO has been assigned to the device/function/index triplet, > +other error codes are used for cases where a GPIO has been assigned but an error > +occured while trying to acquire it. This is useful to discriminate between mere > +errors and an absence of GPIO for optional GPIO parameters. > > Device-managed variants of these functions are also defined: > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 12e47df..32a6e3a 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -2367,7 +2367,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, > unsigned int idx, > enum gpio_lookup_flags *flags) > { > - struct gpio_desc *desc = ERR_PTR(-ENODEV); > + struct gpio_desc *desc = ERR_PTR(-ENOENT); > struct gpiod_lookup_table *table; > struct gpiod_lookup *p; > > @@ -2389,19 +2389,21 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, > chip = find_chip_by_name(p->chip_label); > > if (!chip) { > - dev_warn(dev, "cannot find GPIO chip %s\n", > - p->chip_label); > - continue; > + dev_err(dev, "cannot find GPIO chip %s\n", > + p->chip_label); > + return ERR_PTR(-ENODEV); > } > > if (chip->ngpio <= p->chip_hwnum) { > - dev_warn(dev, "GPIO chip %s has %d GPIOs\n", > - chip->label, chip->ngpio); > - continue; > + dev_err(dev, "requested GPIO %d is out of range [0..%d]" > + " for chip %s\n", idx, chip->ngpio, chip->label); You may leave string literals over 80 character border. chackpatch.pl will not complain about. I might put a) 'dev_warn(dev,', b) '"..."', and c) 'the rest' on three separate lines. > + return ERR_PTR(-EINVAL); > } > > desc = gpiochip_offset_to_desc(chip, p->chip_hwnum); > *flags = p->flags; > + > + return desc; > } > > return desc; > @@ -2413,7 +2415,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, > * @con_id: function within the GPIO consumer > * > * Return the GPIO descriptor corresponding to the function con_id of device > - * dev, or an IS_ERR() condition if an error occured. > + * dev, -ENOENT if no GPIO has been assigned to the requested function, or > + * another IS_ERR() code if an error occured while trying to acquire the GPIO. > */ > struct gpio_desc *__must_check gpiod_get(struct device *dev, const char *con_id) > { > @@ -2430,7 +2433,9 @@ EXPORT_SYMBOL_GPL(gpiod_get); > * This variant of gpiod_get() allows to access GPIOs other than the first > * defined one for functions that define several GPIOs. > * > - * Return a valid GPIO descriptor, or an IS_ERR() condition in case of error. > + * Return a valid GPIO descriptor, -ENOENT if no GPIO has been assigned to the > + * requested function and/or index, or another IS_ERR() code if an error > + * occured while trying to acquire the GPIO. > */ > struct gpio_desc *__must_check gpiod_get_index(struct device *dev, > const char *con_id, > @@ -2455,15 +2460,9 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev, > * Either we are not using DT or ACPI, or their lookup did not return > * a result. In that case, use platform lookup as a fallback. > */ > - if (!desc || IS_ERR(desc)) { > - struct gpio_desc *pdesc; > - > + if (!desc || desc == ERR_PTR(-ENOENT)) { > dev_dbg(dev, "using lookup tables for GPIO lookup"); > - pdesc = gpiod_find(dev, con_id, idx, &flags); > - > - /* If used as fallback, do not replace the previous error */ > - if (!IS_ERR(pdesc) || !desc) > - desc = pdesc; > + desc = gpiod_find(dev, con_id, idx, &flags); > } > > if (IS_ERR(desc)) { -- Andy Shevchenko Intel Finland Oy