mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-08 03:40:35 +09:00
0491709eb3
[ Upstream commit8933d30c5f] The calculation: val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX; do_div(val, lpc18xx_pwm->clk_rate); lpc18xx_pwm->max_period_ns = val; is bogus because with NSEC_PER_SEC = 1000000000, LPC18XX_PWM_TIMER_MAX = 0xffffffff and clk_rate < NSEC_PER_SEC this overflows the (on lpc18xx (i.e. ARM32) 32 bit wide) unsigned int .max_period_ns. This results (dependant of the actual clk rate) in an arbitrary limitation of the maximal period. E.g. for clkrate = 333333333 (Hz) we get max_period_ns = 9 instead of 12884901897. So make .max_period_ns an u64 and pass period and duty as u64 to not discard relevant digits. And also make use of mul_u64_u64_div_u64() which prevents all overflows assuming clk_rate < NSEC_PER_SEC. Fixes:841e6f90bb("pwm: NXP LPC18xx PWM/SCT driver") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.