From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 19 Apr 2012 16:23:06 +0000 Subject: [PATCH 02/16] drivers/gpio: gpio-nomadik: Add support for irqdomains In-Reply-To: References: <1334659448-11521-1-git-send-email-lee.jones@linaro.org> <201204181622.34692.arnd@arndb.de> Message-ID: <201204191623.07445.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wednesday 18 April 2012, Linus Walleij wrote: > > On Wed, Apr 18, 2012 at 6:22 PM, Arnd Bergmann wrote: > > > The problem is that we cannot put the interrupt resources into the platform > > device until the irq domain has been added. Right now, we set the gic > > interrupt domain from init_IRQ(), then add the load the gpio > > driver from core_initcall(nmk_gpio_init) and add the platform devices > > from arch_initcall(customize_machine). > > > > This feels fragile because it depends on the gpio device getting probed > > before any device using the gpio interrupts. It does seem to work fine > > right now, but I'm not convinced that this is just coincidence. > > Aha OK. Why not put in that big comment then, thus nobody will > ever miss the point like I did :-) > I think I've just come up with a solution to this problem and would like to hear what Rob and Grant think about this: If we move the code that adds the resources to a platform_device from of_device_alloc() to platform_drv_probe(), we can defer looking up the interrupt number until the driver actually gets probed and bail out early with -EPROBE_DEFER if the irq domain is not available yet. That will even work when we have a builtin driver for a device that uses a GPIO interrupt and the gpio controller driver is a loadable module. Arnd