On Mon, Feb 19, 2024 at 4:54 PM Théo Lebrun <theo.lebrun@xxxxxxxxxxx> wrote: > > Hello, > > On Mon Feb 19, 2024 at 4:48 PM CET, Bartosz Golaszewski wrote: > > On Wed, Feb 14, 2024 at 5:24 PM Théo Lebrun <theo.lebrun@xxxxxxxxxxx> wrote: > > > > > > Support a single IRQs used by multiple GPIO banks. Change the IRQ > > > handler type from a chained handler (as used by gpiolib > > > for ->parent_handler) to a threaded IRQ. > > > > > > Use a fake raw spinlock to ensure generic_handle_irq() is called in a > > > no-irq context. See Documentation/driver-api/gpio/driver.rst, "CHAINED > > > CASCADED GPIO IRQCHIPS" for additional information. > > > > > > > Any reason for not using preempt_disable()? > > I did what the doc recommended: > > > The generic_handle_irq() is expected to be called with IRQ disabled, > > so the IRQ core will complain if it is called from an IRQ handler which is > > forced to a thread. The "fake?" raw lock can be used to work around this > > problem:: > > > > raw_spinlock_t wa_lock; > > static irqreturn_t omap_gpio_irq_handler(int irq, void *gpiobank) > > unsigned long wa_lock_flags; > > raw_spin_lock_irqsave(&bank->wa_lock, wa_lock_flags); > > generic_handle_irq(irq_find_mapping(bank->chip.irq.domain, bit)); > > raw_spin_unlock_irqrestore(&bank->wa_lock, wa_lock_flags); > > If you confirm I should be using preempt_disable() that's what I'll do > in the next revision. I could even throw in a documentation patch if > the advice is outdated. > > Thanks Bartosz, This was added 9 years ago: commit c307b002548590c5d8c32b964831de671ad4affe Author: Grygorii Strashko <grygorii.strashko@xxxxxx> Date: Tue Oct 20 17:22:15 2015 +0300 gpio: add a real time compliance notes Put in a compliance checklist. Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> I'm Cc'ing Grygorii - maybe he can remember if there was any reason for using a spinlock over preempt_disable(). But for now I'd go with the latter. Bart > > -- > Théo Lebrun, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com