Am Donnerstag, 5. Mai 2011, 12:33:53 schrieb Jonathan Cameron: > On 05/05/11 11:16, Alexander Stein wrote: > > Am Donnerstag, 5. Mai 2011, 12:01:25 schrieb Jonathan Cameron: > >> On 05/05/11 10:44, Alexander Stein wrote: > >>> Am Donnerstag, 5. Mai 2011, 11:08:18 schrieb Jonathan Cameron: > >>>> On 05/05/11 09:32, Alexander Stein wrote: > >>>>> Just set vref_mv in your platform config to use external vref. > >>>>> Otherwise the internal one is used. > >>>> > >>>> Would be nicer to see this done with the regulator framework. But then > >>>> if you have a use case on a board where that isn't available, then > >>>> fair enough. > >>> > >>> Well, for the regulator framework I would redesign the driver a bit. > >>> Currently the analogue inputs are displayed as mV in sysfs. If the > >>> current analogue input voltage is shown via the regulator framework the > >>> ads7846 driver itself can shows the actual ADC values. The latter ones > >>> don't need to know the reference voltage. > >>> But I think this is a different problem than choosing the reference > >>> voltage for an ADC for what this patch is for. > >> > >> I'm somewhat confused by what you mean here. The regulator framework is > >> all about power supplies. This device would merely be a consumer that > >> asks for what (if anything) is being uspplied to the external vref line. > >> Basically it's a more general alternative to supplying the value via > >> platform data. > > > > Maybe I did get you wrong. I thought you meant retrieving the voltage at > > the analogue input somehow using the regulator framework. > > I don't know much about this framework, so how can you handle this: The > > external vref is board-specific, e.g. hard-wired to 3,3V? There is no > > regulator which could adjust the voltage attached to ext vref. > > Yup, you specify it as a fixed voltage regulator. The reason to do this > is that others may well wire it up to a variable regulator (typical > embedded pmic chip for example). Ok, sounds ok to me. But you will then require the regulator framework to be setup for each board using the ads7846 driver. Nevertheless I don't have an elegant idea to switch between internal vref (which is 2,5V fixed) and the (possible variable) ext vref in board-setup. Alexander -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
