On 27 April 2015 at 12:04, Maxime Ripard <maxime.rip...@free-electrons.com> wrote: > On Sun, Apr 26, 2015 at 08:53:16PM +0200, Michal Suchanek wrote: >> >> Also for driver prototyping you need a compatible which makes the >> >> device accessible. >> >> >> >> If no spidev general compatible is available people will just use >> >> compatible for some random device which happens to bind to spidev and >> >> will send many letters of thanks to the DT maintainers when the device >> >> used for this purpose suddenly grows a Linux driver. >> > >> > If people do dumb things, they should expect it to backfire. >> >> Yes, dumb things like not allowing people to say in the DT that the >> board actually has pins on it connected to a SPI bus. Which is the >> actual hardware which should be described in the DT. > > It's not connected to an SPI bus. It's connected to a device using an > SPI bus. If you just had floating SPI lines, I'm pretty sure you > wouldn't care about spidev at all. > >> Do you have to describe a modem or terminal emulator in DT to connect >> it to your serial port? You just describe the port. So here you have a >> SPI port and it should be described in the DT as faithfully as the >> serial port. > > Except that in the serial port, you have a representation of a bus, > while spidev represents a *device* connected on an SPI bus. So these > are two different things, really.
No it's the same thing, really. With serial you just have serial lines which you expose on a connector. With SPI you have CS so you can technically have several connectors for the same SPI bus selected by different CS. So yes, making a spidev entry for the connector under SPI bus is the equivalent of making an UART entry to specify that there is a connector. Thanks Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
