Messages in this thread |  | | Date | Wed, 10 Jun 2009 10:56:33 +0300 | From | Baruch Siach <> | Subject | Re: [PATCH v4] gpio: driver for PrimeCell PL061 GPIO controller |
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On Wed, Jun 10, 2009 at 12:44:47AM -0700, Andrew Morton wrote: > On Wed, 10 Jun 2009 10:22:31 +0300 Baruch Siach <baruch@tkos.co.il> wrote: > > > Hi Andrew, > > > > > > static unsigned int pl061_irq_startup(unsigned irq) > > > > { > > > > - int ret; > > > > - > > > > - ret = gpio_request(irq_to_gpio(irq), "IRQ"); > > > > - if (ret < 0) { > > > > - pr_warning("%s: warning: gpio_request(%d) returned %d\n", > > > > - __func__, irq_to_gpio(irq), ret); > > > > - return 0; > > > > - } > > > > + if (gpio_request(irq_to_gpio(irq), "IRQ") == 0) > > > > + pr_warning("%s: warning: GPIO%d has not been requested\n", > > > > + __func__, irq_to_gpio(irq)); > > > > > > This is wrong, isn't it? gpio_request() returns 0 on success. > > > > Russell said that gpio configuration is the responsibility of the platform > > code. Here I just warn when the gpio has not been requested, and thus > > gpio_request() succeeds. I'll add a comment. > > OK. > > If the gpio_request() accidentally succeeded, should we gpio_free() the > result here?
I don't think so. This is just a warning. We do use this GPIO here, so I guess we should keep it requested.
> Should the gpio core provide a primitive to check that a gpio has been > properly requested rathe rthan open-coding it here?
Probably. The author (maintainer?) of gpiolib, David Brownell, is not responsive at the moment. (I have an SPI master driver waiting for his review/ack).
> > > > static void pl061_irq_handler(unsigned irq, struct irq_desc *desc) > > > > { > > > > + struct list_head *chip_list = get_irq_chip_data(irq); > > > > + struct list_head *ptr; > > > > + struct pl061_gpio *chip; > > > > + > > > > desc->chip->ack(irq); > > > > - while (1) { > > > > + list_for_each(ptr, chip_list) { > > > > > > What locking protects the newly-added list? > > > > Do we need locking even though we list_add() only at probe time? > > Nope. I guess. It depends on the driver. hotplug/hot-remove needs to > beconsidered often. > > > (Compiling as > > a module is not supported, so this only happens at boot time). > > The probe handler is probably serialised against everything else even if > the driver _is_ a module.
baruch
-- ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -
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