Re: [PATCH REPOST] gpio: omap: use raw locks for locking

[Tony Lindgren <tony@xxxxxxxxxxx>]

* Javier Martinez Canillas <javier@xxxxxxxxxxxx> [150619 14:57]:
> On Fri, Jun 19, 2015 at 7:42 PM, santosh shilimkar
> <santosh.shilimkar@xxxxxxxxxx> wrote:
> > On 6/19/2015 10:06 AM, Sebastian Andrzej Siewior wrote:
> >>
> >> This patch converts gpio_bank.lock from a spin_lock into a
> >> raw_spin_lock. The call path is to access this lock is always under a
> >> raw_spin_lock, for instance
> >> - __setup_irq() holds &desc->lock with irq off
> >>    + __irq_set_trigger()
> >>     + omap_gpio_irq_type()
> >>
> >> - handle_level_irq() (runs with irqs off therefore raw locks)
> >>    + mask_ack_irq()
> >>     + omap_gpio_mask_irq()
> >>
> >> This fixes the obvious backtrace on -RT. However the locking vs context
> >> is not and this is not limited to -RT:
> >> - omap_gpio_irq_type() is called with IRQ off and has an conditional
> >>    call to pm_runtime_get_sync() which may sleep. Either it may happen or
> >>    it may not happen but pm_runtime_get_sync() should not be called with
> >>    irqs off.
> >>
> >> - omap_gpio_debounce() is holding the lock with IRQs off.
> >>    + omap2_set_gpio_debounce()
> >>     + clk_prepare_enable()
> >>      + clk_prepare() this one might sleep.
> >>    The number of users of gpiod_set_debounce() / gpio_set_debounce()
> >>    looks low but still this is not good.
> >>
> >> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> >> ---
> >
> > Should be safe to do it.
> > Acked-by: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
> >
> 
> Answered on the wrong thread, sorry for the noise.
> 
> Acked-by: Javier Martinez Canillas <javier@xxxxxxxxxxxx>

Seems OK but looks like this needs updating against current Linux next
to apply though.

Regards,

Tony
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