On Fri, Apr 04, 2014 at 08:30:38AM +0530, Harini Katakam wrote: > On Fri, Apr 4, 2014 at 3:04 AM, Mark Brown <broonie@xxxxxxxxxx> wrote: > > On Thu, Apr 03, 2014 at 04:40:31PM +0530, Harini Katakam wrote: > >> +Optional properties: > >> +- num-cs : Number of chip selects used. > > How does this translate to the hardware? > This IP can drive 4 slaves. > The CS line to be driven is selected in spi device structure and > that is driven by the software. So why specify this in the binding at all? If the device always has the same number of chip selects it's redundant. > >> + num-cs = /bits/ 16 <4>; > > What's going on with the /bits/ - is this something that's required for > > the property? > The master->num-chipselect property is 16 bit but writing <4> here directly > leads to 0 being read in of_property_read (because it's big endian). > Instead using of property read u32 and then copying, we decided to do this. > This was discussed on v2 between Michal and Rob: No, don't do that. You're contorting the binding to serve Linux's implementation needs and you've not documented this requirement either. If there *was* a need to have the number be 16 bits you'd need to document that reqirement in the binding, though like I say I don't think the number needs to be there at all.
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