On Fri, Sep 25, 2015 at 12:28 PM, Grygorii Strashko <grygorii.strashko@xxxxxx> wrote: > This patch converts TI OMAP GPIO driver to use generic irq handler > instead of chained IRQ handler. This way OMAP GPIO driver will be > compatible with RT kernel where it will be forced thread IRQ handler > while in non-RT kernel it still will be executed in HW IRQ context. > As part of this change the IRQ wakeup configuration is applied to > GPIO Bank IRQ as it now will be under control of IRQ PM Core during > suspend. > > There are also additional benefits: > - on-RT kernel there will be no complains any more about PM runtime usage > in atomic context "BUG: sleeping function called from invalid context"; > - GPIO bank IRQs will appear in /proc/interrupts and its usage statistic > will be visible; > - GPIO bank IRQs could be configured through IRQ proc_fs interface and, > as result, could be a part of IRQ balancing process if needed; > - GPIO bank IRQs will be under control of IRQ PM Core during > suspend to RAM. > > Disadvantage: > - additional runtime overhed as call chain till > omap_gpio_irq_handler() will be longer now > - necessity to use wa_lock in omap_gpio_irq_handler() to W/A warning > in handle_irq_event_percpu() > WARNING: CPU: 1 PID: 35 at kernel/irq/handle.c:149 handle_irq_event_percpu+0x51c/0x638() > > This patch doesn't fully follows recommendations provided by Sebastian > Andrzej Siewior [1], because It's required to go through and check all > GPIO IRQ pin states as fast as possible and pass control to handle_level_irq > or handle_edge_irq. handle_level_irq or handle_edge_irq will perform actions > specific for IRQ triggering type and wakeup corresponding registered > threaded IRQ handler (at least it's expected to be threaded). > IRQs can be lost if handle_nested_irq() will be used, because excecution > time of some pin specific GPIO IRQ handler can be very significant and > require accessing ext. devices (I2C). > > Idea of such kind reworking was also discussed in [2]. > > [1] http://www.spinics.net/lists/linux-omap/msg120665.html > [2] http://www.spinics.net/lists/linux-omap/msg119516.html > > Tested-by: Tony Lindgren <tony@xxxxxxxxxxx> > Tested-by: Austin Schuh <austin@xxxxxxxxxxxxxxxx> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> Patch applied. I'm thinking that we need some recommendations on how to write IRQ handlers in order to be RT-compatible. Can you help me lining up the requirements in Documentation/gpio/driver.txt? I will write an RFC patch and let you write some additional text to it in response then we can iterate it a bit. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
