On 05/18/2012 06:57 PM, Johan Hovold wrote: > On Fri, May 18, 2012 at 06:34:01PM +0100, Jonathan Cameron wrote: >> On 05/18/2012 01:27 PM, Johan Hovold wrote: > > [...] > >>> I really think that this should remain a device specific attribute as I >>> originally suggested. It's an integration parameter that needs to be set >>> precisely depending on the actual hardware setup (which analog light >>> sensor and other external components). >> Then it shouldn't be exposed to userspace. If there is reason to vary >> it from userspace then it is a calibration parameter and should be >> treated like the other ones we have, if not it should be done from >> dt or platform data. >>> >>> The lm3533 also supports two types of light sensors: pwm- and analog- >>> output ones. The resistor select settings only applies when in analog >>> mode as the input is always high impedance otherwise. Thus a generic >>> attribute (such as calibscale or hardware gain) shouldn't be used as it >>> will have no effect whatsoever in PWM-mode. >>> >>> I'm thus back at my original proposal, albeit with a different name (I >>> think a lot of this discussion could have been avoided had I not >>> misnamed the parameter "gain"): >>> >>> What: /sys/bus/iio/devices/iio:deviceX/r_select >>> Description: >>> Set the ALS internal pull-down resistor for analog input mode >>> (1..127), such that, >>> >>> R_als = 200000 / r_select (ohm) >>> >>> This setting is ignored in PWM-mode (input is always high >>> impedance in PWM-mode). >>> >>> I don't think much is gained from using ohm as the unit: it just adds >>> complexity and the selected resistor setting will likely not match the >>> input value anyway. It's better that the chip integrators have full >>> control over which resistor setting is actually used so that it matches >>> external components. >> This smacks of something that should never be exposed to users. >> I'd hide it away in platform data. > > Fair enough. I'll drop the sysfs param and submit a patch for mfd-next > which adds r_select to the platform data. > cool. I'll review the rest of the patch with the assumption you'll do this. Jonathan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
