On 5/24/2016 10:41 AM, Mark Rutland wrote: > On Tue, May 24, 2016 at 06:39:20PM +0200, Christer Weinigel wrote: >> Document how to use devicetree aliases to assign a stable >> bus number to a spi bus. >> >> Signed-off-by: Christer Weinigel <christer@xxxxxxxxxxx> >> >> --- >> >> Trivial documentation change. >> >> Not having used devicetree that much it was surprisingly hard to >> figure out how to assign a stable bus number to a spi bus. Add a >> simple example that shows how to do that. >> >> Mark Cced as the SPI maintainer. Or should trivial documentation >> fixes like this be addressed to someone else? >> >> /Christer >> >> Documentation/devicetree/bindings/spi/spi-bus.txt | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt >> index 42d5954..c35c4c2 100644 >> --- a/Documentation/devicetree/bindings/spi/spi-bus.txt >> +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt >> @@ -94,3 +94,13 @@ SPI example for an MPC5200 SPI bus: >> reg = <1>; >> }; >> }; >> + >> +Normally SPI buses are assigned dynamic bus numbers starting at 32766 >> +and counting downwards. It is possible to assign the bus number >> +statically using devicetee aliases. For example, on the MPC5200 the >> +"spi@f00" device above is connected to the "soc" bus. To set its >> +bus_num to 1 add an aliases entry like this: > > As Mark Brown pointed out, this is very Linux-specific (at least in the > wording of the above). Yes, Linux-specific. So the Linux documentation of bindings is the correct place for it. > > Generally, aliases are there to match _physical_ identifiers (e.g. to > match physical labels for UART0, UART1, and on). > > I'm not sure whether that applies here. The code and behavior is in the Linux kernel. It should be visible in the documentation instead of being a big mystery of how it works. > > Thanks, > Mark. > -- > 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 > -- 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
