Messages in this thread | | | Date | Thu, 8 Sep 2011 18:35:44 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] leds/of: leds-gpio.c: Use gpio_get_value_cansleep() when initializing. |
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On Tue, 30 Aug 2011 16:39:52 -0700 David Daney <david.daney@cavium.com> wrote:
> I get the following warning: > > ------------[ cut here ]------------ > WARNING: at drivers/gpio/gpiolib.c:1559 __gpio_get_value+0x90/0x98() > Modules linked in: > Call Trace: > [<ffffffff81440950>] dump_stack+0x8/0x34 > [<ffffffff81141478>] warn_slowpath_common+0x78/0xa0 > [<ffffffff812f0958>] __gpio_get_value+0x90/0x98 > [<ffffffff81434f04>] create_gpio_led+0xdc/0x194 > [<ffffffff8143524c>] gpio_led_probe+0x290/0x36c > [<ffffffff8130e8b0>] driver_probe_device+0x78/0x1b0 > [<ffffffff8130eaa8>] __driver_attach+0xc0/0xc8 > [<ffffffff8130d7ac>] bus_for_each_dev+0x64/0xb0 > [<ffffffff8130e130>] bus_add_driver+0x1c8/0x2a8 > [<ffffffff8130f100>] driver_register+0x90/0x180 > [<ffffffff81100438>] do_one_initcall+0x38/0x160 > > ---[ end trace ee38723fbefcd65c ]--- > > My GPIOs are on an I2C port expander, so we must use the *_cansleep() > variant of the GPIO functions. This is was not being done in > create_gpio_led(). > > We can change gpio_get_value() to gpio_get_value_cansleep() because it > is only called from the platform_driver probe function, which is a > context where we can sleep. > > Only tested on my gpio_cansleep() system, but it seems safe for all > systems. > > ... > > --- a/drivers/leds/leds-gpio.c > +++ b/drivers/leds/leds-gpio.c > @@ -121,7 +121,7 @@ static int __devinit create_gpio_led(const struct gpio_led *template, > } > led_dat->cdev.brightness_set = gpio_led_set; > if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) > - state = !!gpio_get_value(led_dat->gpio) ^ led_dat->active_low; > + state = !!gpio_get_value_cansleep(led_dat->gpio) ^ led_dat->active_low; > else > state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); > led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
gpio_get_value() is an architecture-specific function whereas gpio_get_value_cansleep() is not. Hence all architectures will now be forced to use the same code. Why is this OK?
Asides:
The duplication of code between __gpio_get_value() and gpio_get_value_cansleep() is daft.
The comment over gpio_get_value_cansleep() sucks mud rocks.
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