Add an explanation why zero width check is needed when generating factor
mask using GENMASK() macro.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
ccu_nkmp_find_best(parent_rate, rate, &_nkmp);
+ /*
+ * If width is 0, GENMASK() macro may not generate expected mask (0)
+ * as it falls under undefined behaviour by C standard due to shifts
+ * which are equal or greater than width of left operand. This can
+ * be easily avoided by explicitly checking if width is 0.
+ */
if (nkmp->n.width)
n_mask = GENMASK(nkmp->n.width + nkmp->n.shift - 1,
nkmp->n.shift);