On Thu, Dec 03, 2015 at 12:07:26PM +0100, Takashi Iwai wrote: > Mark Brown wrote: > > On Thu, Dec 03, 2015 at 10:41:38AM +0100, Takashi Iwai wrote:
> > > While reading this patch, I wondered how regmap can be used safely in > > > an irq-disabled context. Mark, do we have any API for that? > > We can use user supplied locks or spin_lock_irqsave(). > I meant how to guarantee to make regmap_read() working in an already > spin-locked context, typically in an irq handler? regmap_read() > involves with the regcache and it may invoke kmalloc(). I know that's what you meant - that should be done by preallocating the cache (which can be done with defaults) and providing your own lock if there's a spinlock already held (since we use _irqsave() which IIRC isn't nestable). We can also use GFP_ATOMIC for some of the allocations in reasonable use cases but it's not in general supported.
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