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

[santosh shilimkar <santosh.shilimkar@oracle.com>]

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@linutronix.de>
> ---
Should be safe to do it.
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>

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