On Fri, Jun 17, 2016 at 04:57:21PM +0900, Andi Shyti wrote:
> Some SPI connected devices do not have any CS line connected as
> some devices are alway enabled. Indeed, until now, a common
> workaround was to assign to num_chipselect a -1 value or 255
> (num_chipselect is unsigned).
> 
> In this case do not fail and defer to the SPI device drivers the
> responsibility to check whether the num-cs is '0'.

A SPI controller always has one chip seelct, it may not be controllable
but it's at least logically present.