Mark Brown wrote at Thursday, July 14, 2011 6:25 AM: > On Wed, Jul 13, 2011 at 02:40:17PM -0600, Stephen Warren wrote: > > > + gpio_request(TEGRA_GPIO_CDC_IRQ, "wm8903"); > > + gpio_direction_input(TEGRA_GPIO_CDC_IRQ); > > + > > i2c_register_board_info(0, &wm8903_board_info, 1); > > This seems silly - we should fix this in the core code rather than have > every single board that ahppens to use an interrupt which is also > available as a GPIO manually faff around with gpiolib. That seems a good goal. However, how does the WM8903 driver know whether the interrupt number it's passed is a straight-up dedicated interrupt (hence the calls aren't required), or a GPIO (hence they are)? I guess the answer is that there should be an interrupt API to map from interrupt to GPIO number, returning <0 when there is no GPIO backing the IRQ, and an op in struct irq_chip to implement that? However, that's not there right now as far as I can tell. Finally, there are some pinmux interactions that need to be dealt with; on Tegra, the pinmux allows the tristate/drive status of pins to be set on a group basis (a group being a set of 1-n pins). However, gpio enable (which overrides the pinmux's setting of tristate/drive) can be set on a per-pin basis. At least on Seaboard, the WM8903 IRQ is an input pin in a group that otherwise needs to contain output pins, so we really want to enable the WM8903 IRQ GPIO pin as a GPIO, and set it to input, before setting up that pinmux group to drive the pins. Without this, there may be a brief period where both Tegra and the WM8903 are driving this IRQ signal, which can't be good for hardware. -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
