Messages in this thread | | | Date | Thu, 3 Nov 2005 16:34:45 +0100 | From | Vojtech Pavlik <> | Subject | Re: best way to handle LEDs |
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On Thu, Nov 03, 2005 at 02:49:04PM +0000, Russell King wrote: > On Thu, Nov 03, 2005 at 10:57:26AM +0100, Pavel Machek wrote: > > Hi! > > > > > > Except the led code that is being proposed CAN sit on top of a generic > > > > GPIO layer. > > > > > > I also have issues with a generic GPIO layer. As I mentioned in the > > > past, there's serious locking issues with any generic abstraction of > > > GPIOs. > > > > > > 1. You want to be able to change GPIO state from interrupts. This > > > implies you can not sleep in GPIO state changing functions. > > > > > > 2. Some GPIOs are implemented on I2C devices. This means that to > > > change state, you must sleep. > > > > Can't you just busywait? Yes, it is ugly in general, but perhaps it > > is better than alternatives... > > Does the i2c layer support busy waiting or are you suggesting something > else?
It usually doesn't support anything else. At least on the controllers I've seen the drivers for.
-- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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