Re: [uclinux-dist-devel] [PATCH] serial: bfin_5xx: split uart RX lock from uart port lock to avoid deadlock

[Greg KH <greg@kroah.com>]

On Thu, Feb 03, 2011 at 01:29:08AM -0500, Mike Frysinger wrote:
> On Tue, Jan 11, 2011 at 00:16, Mike Frysinger wrote:
> > From: Sonic Zhang <sonic.zhang@analog.com>
> >
> > The RX lock is used to protect the RX buffer from concurrent access in DMA
> > mode between the timer and RX interrupt routines.  It is independent from
> > the uart lock which is used to protect the TX buffer.  It is possible for
> > a uart TX transfer to be started up from the RX interrupt handler if low
> > latency is enabled.  So we need to split the locks to avoid deadlocking in
> > this situation.
> >
> > In PIO mode, the RX lock is not necessary because the handle_simple_irq
> > and handle_level_irq functions ensure driver interrupt handlers are called
> > once on one core.
> >
> > And now that the RX path has its own lock, the TX interrupt has nothing to
> > do with the RX path, so disabling it at the same time.
> 
> ping ...

Is this needed for .38?

thanks,

greg k-h
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