On Sat, Dec 13, 2014 at 12:18:50PM +0100, Hartmut Knaack wrote: > Nikolaus Schulz schrieb am 12.12.2014 um 16:58: > > On Sat, Dec 06, 2014 at 12:36:19PM +0100, Hartmut Knaack wrote: > >> Nikolaus Schulz schrieb am 24.11.2014 um 20:50: > >>> The TI DAC8554 is a quad-channel Digital-to-Analog Converter with an SPI > >>> interface. [dac8554_probe:] > >>> + st->vref_mv =oltage_uv / 1000; > >> How hard do you want to depend on a voltage regulator? Doing regulator_get_voltage() > >> could even be called dynamically in _read_raw(), making a real regulator optional. > > > > Hmm. I understand that the DAC voltage input may not be provided by a > > regulator, but is that a common scenario? No other DAC driver I looked > > at handles that case, they all consider it an error if the regulator is > > absent. > > > I had people in mind, who might want to use such DAC with one of the popular > embedded boards like Raspberry Pi - people who would just like to "plug and > play" without the need or ability to build a kernel (or would prefer to go > with the convenience of a distribution kernel). But since you've put a > dependency on OF, I don't see a way to use this device with a stock distribution > kernel anyway. As long as the kernel supports devicetree, compiling the module and a new DT blob should be enough to enable support for the DAC8554. And, as Jonathan has pointed out, if there is no real regulator providing the input current, a fixed regulator can be added to the DT. > But I still think that calculating the actual voltage during _read_raw() would > be a good idea, as there is support for regulators providing different voltages, > which can be changed during runtime. Agreed. -- Avionic Design GmbH Nikolaus Schulz Wragekamp 10 D-22397 Hamburg Germany Tel.: +49 40 88187-163 Fax: +49 40 88187-150 Email: nikolaus.schulz@xxxxxxxxxxxxxxxxx Avionic Design GmbH Amtsgericht Hamburg HRB 82598 Geschäftsführung: Cornelis Broers Ust.-Ident-Nr.: DE813378254 -- 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
