[06/10,V2] spi: Add SPI driver for mx233/mx28

[Lothar Waßmann]

Shawn Guo writes:
> On Wed, Aug 01, 2012 at 08:45:19AM +0200, Marek Vasut wrote:
> > > I must be missing something.  Why do almost all spi drivers call it in the
> > > error path, even if there is no call to spi_master_get ?
> > 
> > To push the refcounting to 0, to deallocate the device, I'd say ...
> > 
> It's not going to work if spi_master_put is called without
> spi_master_get being called before that.
> 
spi_alloc_master() calls device_initialize() which resuires a
device_put() (called from spi_master_put()) to free the device.

Thus each call of either spi_alloc_master() or spi_master_get() must
be paired with an spi_master_put() call to free the resources.

The kfree() is taken care of by the spi_master_release() function that
is called once the last reference to the underlying struct device has
been released. Thus kfree() must not be called after
spi_alloc_master().


Lothar Waßmann
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