On Thu, Aug 13, 2015 at 4:58 PM, Grygorii Strashko
<grygorii.strashko@xxxxxx> wrote:
> Since IRQ chip helpers were introduced drivers lose ability to
> register separate lockdep classes for each registered GPIO IRQ
> chip and the gpiolib now is using shared lockdep class for
> all GPIO IRQ chips (gpiochip_irq_lock_class).
> As result, lockdep will produce warning when there are min two
> stacked GPIO chips and all of them are interrupt controllers.
>
> HW configuration which generates lockdep warning (TI dra7-evm):
(...)
>
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: Roger Quadros <rogerq@xxxxxx>
> Reported-by: Roger Quadros <rogerq@xxxxxx>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Ah, I see...
> * implies that if the chip supports IRQs, these IRQs need to be threaded
> * as the chip access may sleep when e.g. reading out the IRQ status
> * registers.
> + * @exported: flags if the gpiochip is exported for use from sysfs. Private.
> * @irq_not_threaded: flag must be set if @can_sleep is set but the
> * IRQs don't need to be threaded
> *
> @@ -126,6 +128,7 @@ struct gpio_chip {
> irq_flow_handler_t irq_handler;
> unsigned int irq_default_type;
> int irq_parent;
> + struct lock_class_key *lock_key;
There is something weird with the kerneldoc. It is documenting something
else but not documenting the new member.
Anyway, so here:
> +int _gpiochip_irqchip_add(struct gpio_chip *gpiochip,
> + struct irq_chip *irqchip,
> + unsigned int first_irq,
> + irq_flow_handler_t handler,
> + unsigned int type,
> + struct lock_class_key *lock_key);
> +
> +#ifdef CONFIG_LOCKDEP
> +#define gpiochip_irqchip_add(...) \
> +( \
> + ({ \
> + static struct lock_class_key _key; \
> + _gpiochip_irqchip_add(__VA_ARGS__, &_key); \
> + }) \
> +)
> +#else
> +#define gpiochip_irqchip_add(...) \
> + _gpiochip_irqchip_add(__VA_ARGS__, NULL)
> +#endif
Every chip will get their own lock class on the heap.
But I think it is a bit kludgy.
Is it not possible to have the lock key in struct gpio_chip
be a real member instead of a pointer and get a per-chip
lock that way?
(...)
struct lock_class_key lock_key;
instead of:
struct lock_class_key *lock_key;
-> problem solved, without kludgy header defines?
Yours,
Linus Walleij
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