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authorDavid Rivshin <drivshin@allworx.com>2016-01-29 23:26:53 -0500
committerThierry Reding <thierry.reding@gmail.com>2016-03-23 17:11:47 +0100
commit7b0883f33809ff0aeca9848193c31629a752bb77 (patch)
tree2c3a38a5419fa19b716d5aad77a48702257dc30a /drivers/pwm
parentcd378881426379a62a7fe67f34b8cbe738302022 (diff)
downloadlinux-7b0883f33809ff0aeca9848193c31629a752bb77.tar.bz2
pwm: omap-dmtimer: Round load and match values rather than truncate
When converting period and duty_cycle from nanoseconds to fclk cycles, the error introduced by the integer division can be appreciable, especially in the case of slow fclk or short period. Use DIV_ROUND_CLOSEST_ULL() so that the error is kept to +/- 0.5 clock cycles. Fixes: 6604c6556db9 ("pwm: Add PWM driver for OMAP using dual-mode timers") Signed-off-by: David Rivshin <drivshin@allworx.com> Acked-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/pwm-omap-dmtimer.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
index 54641e45f45b..e0679eb399f6 100644
--- a/drivers/pwm/pwm-omap-dmtimer.c
+++ b/drivers/pwm/pwm-omap-dmtimer.c
@@ -49,11 +49,7 @@ to_pwm_omap_dmtimer_chip(struct pwm_chip *chip)
static u32 pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate, int ns)
{
- u64 c = (u64)clk_rate * ns;
-
- do_div(c, NSEC_PER_SEC);
-
- return c;
+ return DIV_ROUND_CLOSEST_ULL((u64)clk_rate * ns, NSEC_PER_SEC);
}
static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)