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. 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? * 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)? * 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?) * 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. * Would IRQF_SHARED be appropriate to enable opening IRQ enabled GPIO blocks multiple times? Thanks, Roland -- 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/
