On 07/27/2015 02:50 PM, Linus Walleij wrote: > Patch applied. thanks. > > Now this question appear in my head: > > Is drivers/gpio full of stuff that will not work with the -RT kernel, > and is this a change that should be done mutatis mutandis on > all the GPIO drivers?
I described two call paths where you need a rawlock_t. If your gpio driver uses irq_chip_generic then you a rawlock here and things should be fine. In general: If your gpio controller acts as an interrupts controller (that is via chained handler) then you need the raw-locks if you need any locking (if you have a write 1 to mask/unmask/enable/disable register then you probably don't need any locking here at all). If the gpio controller does not act as an interrupt controller than the spinlock_t type should be enough. If your gpio-interrupt controller requests its interrupt via requested_threaded_irq() then it should do handle_nested_irq() and a mutex is probably used for locking. Using request_irq() with "0" flags is kind of broken. It works in IRQ-context and delivers the interrupts with generic_handle_irq() and this one passes it the handler (like handle_edge_irq() / handle_level_irq()) which takes a raw_lock. Now, if you boot the vanilla kernel with threadedirq then the irq-handler runs in threaded context and you can't take a spinlock here anymore. So I think you should use here IRQF_NO_THREAD here (and the raw lock type). I added tglx on Cc: to back up because it is Monday. > Yours, > Linus Walleij > Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
