Hi Roland, On 12/04/2012 09:39 PM, Roland Stigge wrote: > Hi Wolfgang, > > On 03/12/12 10:17, Wolfgang Grandegger wrote: >> I re-tried v8 on my AT91-SAM9G45 board and it works fine if >> CONFIG_GPIO_SYSFS is enable. Unfortunately, the access via misc device >> fails if CONFIG_GPIO_SYSFS is not set. That's due to gpio_block_export() >> returning -ENOSYS in gpio_block_register(). >> >> Anyway, I really like that new GPIO block interface making life for >> applications fiddling with GPIOs much easier and faster. Just the poll >> support is missing. > > Thanks for your feedback! > > I'm posting an update (v9) which includes poll() support in the dev > interface.
I just gave it a try and it was working after replacing IRQF_TRIGGER_FALLING with 0 in the request_irq in the device open: # ./gpio_block_test mask=0x7e mask=0x7f mask=0x7d mask=0x7f mask=0x77 mask=0x7f Otherwise it get: # ./gpio_block_test genirq: Setting trigger mode 2 for irq 86 failed (gpio_irq_type+0x0/0x18) can't open device /dev/gpiobuttons (Invalid argument) Also opening with O_NONBLOCK works as expected. > Some issues regarding IRQ driven poll() remain: > > * What would be the correct locking mechanism for the got_int flag (set > in the isr and reset on read()'s return), if necessary at all? If you sync against the interrupt context, I think spin_lock_irqsave and spin_unlock_irqrestore should be used. > * There is probably an explicit interrupt configuration necessary (via > struct gpio_block, and devicetree, respectively) since there are > constellations where gpio_to_irq() isn't working. E.g., in contrast to > controllers which are aware of their IRQs and providing to_irq(), there > is typically independent wiring from GPIO expander chips' interrupt line > to individual IRQ inputs on SoCs/CPUs. Or should all this be solved via > devicetree and drivers (which should support IRQ config where possible)? Yes, I think it's up to the device tree or platform code to properly setup the interrupt... like for defining the GPIO block. > * For the same reason, the IRQ flags are currently IRQF_TRIGGER_FALLING, > which isn't flexible. Instead, either preset by board setup/firmware, or > via interrupts config in devicetree (optional property of a GPIO block?) Yes, and it did fail on my setup. > * Some GPIOs' IRQs are not suitable for GPI input change detection. E.g. > on LPC32xx, I can configure the IRQ which is controlled directly by the > GPI's values as FALLING, RISING, HIGH /exclusive/ or LOW. I.e., this way > it's not possible to detect both 0->1 and 1->0 changes without > reconfiguring the GPIO controller inbetween. Other controllers provide a > dedicated interrupt on all values changes. Hm. > * Would IRQF_SHARED be appropriate to enable opening IRQ enabled GPIO > blocks multiple times? Sounds reasonable for me. Some more comments in the patch mails... Wolfgang. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
