Hi Hector, > Hello, > > On 07/05/2013 03:10 PM, Marek Vasut wrote: > > Dear Hector Palacios, > > > >> Dear Marek, > >> > >> On 07/05/2013 01:37 PM, Marek Vasut wrote: > >>> Dear Hector Palacios, > >>> > >>>> The LRADC virtual channels have an 18 bit field to store the sum of up > >>>> to 2^5 accumulated samples. The read_raw function however only > >>>> operates over a single sample (12 bit resolution). > >>>> In order to use this field for scaling operations, we need it to be > >>>> the exact resolution value of the LRADC. > >>> > >>> How would this work once the accumulation is supported? > >> > >> As I see it, when you read a channel the driver should give you the > >> 12-bit value either of one single sample or of N samples. > > > > The hardware will always give you 18 bit value, let's call it A of N > > accumulated samples, each 12 bit long. N is in range of 1 to 32 . > > > > The driver currently supports N = 1. > > > > Do I understand it correctly that if we want to support N > 1, we have to > > do the division of A / N in the driver and therefore we will again > > report only a 12-bit value to the userland ? > > > > If so, > > > > Acked-by: Marek Vasut <marex@xxxxxxx> > > Coming back to this patch, I just noticed that it is not enough to just > change the realbits from 18 to 12. When using this driver as touchscreen > for Yocto's SATO graphic rootfs I noticed that the driver is using > LRADC_CH_VALUE_MASK for reporting the coordinates. > > input_set_abs_params(input, ABS_X, 0, LRADC_CH_VALUE_MASK, 0, 0); > input_set_abs_params(input, ABS_Y, 0, LRADC_CH_VALUE_MASK, 0, 0); > input_set_abs_params(input, ABS_PRESSURE, 0, LRADC_CH_VALUE_MASK, 0, 0); > > which is defined as an 18bit mask: > > #define LRADC_CH_VALUE_MASK 0x3ffff > > The result is that the touch calibration range in Xorg is expecting values > between 0 and 262143 (0x3ffff), which causes trouble (at least I had > problems to calibrate it). What kind of trouble does it cause? [...] > Notice that I leave the existing LRADC_CH_VALUE_MASK 18bit mask in the rest > of the driver, to support accumulated samples. > Curiously, ts_lib works fine without this (maybe the calibration fixes > this?), but nevertheless the information passed by the driver is > incorrect, I guess. Is anybody out there working with the touch? Under > which graphic system? Both QtE and Sato work for me, that's why I'm curious about your issues. Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
