Commits
Hans de Goede committed 34f326e702f
pwm: lpss: Fix off by one error in base_unit math in pwm_lpss_prepare() [ Upstream commit 181f4d2f44463fe09fe4df02e03095cb87151c29 ] According to the data-sheet the way the PWM controller works is that each input clock-cycle the base_unit gets added to a N bit counter and that counter overflowing determines the PWM output frequency. So assuming e.g. a 16 bit counter this means that if base_unit is set to 1, after 65535 input clock-cycles the counter has been increased from 0 to 65535 and it will overflow on the next cycle, so it will overflow after every 65536 clock cycles and thus the calculations done in pwm_lpss_prepare() should use 65536 and not 65535. This commit fixes this. Note this also aligns the calculations in pwm_lpss_prepare() with those in pwm_lpss_get_state(). Note this effectively reverts commit 684309e5043e ("pwm: lpss: Avoid potential overflow of base_unit"). The next patch in this series really fixes the potential overflow of the base_unit value. Fixes: 684309e5043e ("pwm: lpss: Avoid potential overflow of base_unit") Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200903112337.4113-4-hdegoede@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org>