On Mon, Jan 22, 2018 at 1:03 AM, David Lechner [off-list ref] wrote:

This fixes pcs_request_gpio() in the pinctrl-single driver when
bits_per_mux != 0. It appears this was overlooked when the multiple
pins per register feature was added.

Fixes: 4e7e8017a80e ("pinctrl: pinctrl-single: enhance to configure
multiple pins of different modules")

One line?

+                       byte_num = (pcs->bits_per_pin * pin) / BITS_PER_BYTE;
+                       offset = (byte_num / mux_bytes) * mux_bytes;
+                       pin_shift = pin % (pcs->width / pcs->bits_per_pin) *
+                                   pcs->bits_per_pin;

Sounds like playing around pretty well defined macro and functions,
e.g. DIV_ROUND_UP(), round_up().

-- 
With Best Regards,
Andy Shevchenko