Dmitry, On 6/16/2016 4:17 PM, Vignesh R wrote: [...] >>> On 5/20/2016 10:04 PM, Dmitry Torokhov wrote: >>>> On Thu, May 19, 2016 at 02:34:00PM +0530, Vignesh R wrote: >>>>> There are rotary-encoders where GPIO lines reflect the actual position >>>>> of the rotary encoder dial. For example, if dial points to 9, then four >>>>> GPIO lines connected to the rotary encoder will read HLLH(1001b = 9). >>>>> Add support for such rotary-encoder. >>>>> The driver relies on rotary-encoder,absolute-encoder DT property to >>>>> detect such encoders. >>>>> Since, GPIO IRQs are not necessary to work with >>>>> such encoders, optional polling mode support is added using >>>>> input_poll_dev skeleton. This is can be used by enabling >>>>> CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT. >>>> >>>> Does this really belong to a rotary encoder and not a new driver that >>>> simply translates gpio-encoded value into ABS* event? >>>> >>> >>> Currently rotary encoder driver only supports incremental/step counting >>> rotary devices. However, the device that is there on am335x-ice is an >>> absolute encoder but, IMO, nevertheless a kind of rotary encoder. The >>> only difference is that there is no need to count steps and the absolute >>> position value is always available as binary encoded state of connected >>> GPIOs. >>> The hardware on am335x-ice is a mechanical rotary encoder switch >>> connected over 4 GPIOs. It is same as binary encoder described at [1] >>> (except there are 4 GPIO lines), so this lead me to add support in >>> rotary-encoder. >>> >>> [1]https://en.wikipedia.org/wiki/Rotary_encoder#Standard_binary_encoding >>> >> >> Could you please comment on how would you like to support above >> described encoder: As a new driver or with existing driver with new >> compatible/mode setting via DT or as suggest by Uwe in another reply? >> IMHO, supporting using existing driver with new mode/compatible string >> looks a better option as the hardware is a kind of rotary-encoder. >> Could you please suggest the right solution here? Do you think new driver is need to support above described absolute encoder h/w? It would be great to have your input now, so that I can work on the new set of patches and submit them for v4.9 merge window as soon as v4.8 merge window closes? Regards Vignesh -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
