Re: rt-mutex usage in i2c

[Wolfram Sang <wsa@the-dreams.de>]

[-- Attachment #1: Type: text/plain, Size: 956 bytes --]

On Sat, Mar 14, 2015 at 12:27:03PM +0100, Wolfram Sang wrote:
> Hi Sebastian,
> 
> > - i2c_transfer() has this piece:
> >   2091                 if (in_atomic() || irqs_disabled()) {
> >   2092                         ret = i2c_trylock_adapter(adap);
> > 
> >   is this irqs_disabled() is what bothers me and should not be there.
> >   pxa does a spin_lock_irq() which would enable interrupts on return /
> >   too early.
> >   mxs has a wait_for_completion() which needs irqs enabled _and_ makes
> >   in_atomic() problematic, too. I have't checked other drivers but the
> >   commit, that introduced it, does not explain why it is required.
> 
> I haven't really looked into it, but a quick search gave me this thread
> explaining the intention of the code in question:
> 
> http://lists.lm-sensors.org/pipermail/i2c/2007-November/002268.html
> 
> Regards,
> 
>    Wolfram
> 

And adding a recent mail address from Mike to cc.


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]