Hi, On Fri, Apr 4, 2014 at 7:38 PM, Harini Katakam <harinikatakamlinux@xxxxxxxxx> wrote: > Hi Mark, > > On Fri, Apr 4, 2014 at 6:16 PM, Mark Brown <broonie@xxxxxxxxxx> wrote: >> On Fri, Apr 04, 2014 at 05:44:23PM +0530, Harini Katakam wrote: >>> On Fri, Apr 4, 2014 at 3:39 PM, Mark Brown <broonie@xxxxxxxxxx> wrote: >>> > On Fri, Apr 04, 2014 at 08:30:38AM +0530, Harini Katakam wrote: >> >>> >> 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. >> >>> I'm sorry, I should have explained that better. >>> The IP can support upto 4 chip selects. >>> The num-cs value here is the number of chip selects actually used on the board. >> >> Why does that need to be configured? Surely the presence of slaves is >> enough information. > > OK. I understand. > Can you comment on the case where a decoder is used? > > There is support for adding a decoder where extended slaves can be selected > through the IP's control register. > (This is not currently implemented in the driver but will be in the future.) > > How should the driver know whether it is 4 or 16 select lines for example? > This has to be written to master->num_chipselect. > > Regards, > Harini Just adding to my above comment. Alternately, I could not use the "num-cs" property and add another optional property to be used only when required. The driver sets a default value already. Regards, Harini -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
