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author | Vladimir Zapolskiy <vz@mleia.com> | 2015-12-06 13:32:02 +0200 |
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committer | Thierry Reding <thierry.reding@gmail.com> | 2015-12-16 17:01:06 +0100 |
commit | d6dbdf0ddefa581e49c2abe5fb0eb17d14111d89 (patch) | |
tree | 49d6a3c2c8119480c873eb8f2cf7da9d16a2f2a5 /drivers/pwm/pwm-rcar.c | |
parent | 5a9fc9c666d5d759699cf5495bda85f1da0d747e (diff) | |
download | linux-d6dbdf0ddefa581e49c2abe5fb0eb17d14111d89.tar.gz linux-d6dbdf0ddefa581e49c2abe5fb0eb17d14111d89.tar.bz2 linux-d6dbdf0ddefa581e49c2abe5fb0eb17d14111d89.zip |
pwm: lpc32xx: return ERANGE, if requested period is not supported
Instead of silent acceptance of unsupported requested configuration
for PWM period and setting the boundary supported value, return
-ERANGE to a caller.
Duty period value equal to 0 or period is still accepted to allow
configuration by PWM sysfs interface, when it is set to 0 by default.
For reference this is a list of restrictions on period_ns == 1/freq:
| PWM parent clock | parent clock divisor | max freq | min freq |
+------------------+----------------------+----------+----------+
| HCLK == 13 MHz | 1 (min) | 50.7 KHz | 198.3 Hz |
| HCLK == 13 MHz | 15 (max) | 3.38 KHz | 13.22 Hz |
| RTC == 32.7 KHz | 1 (min) | 128 Hz | 0.5 Hz |
| RTC == 32.7 KHz | 15 (max) | 8.533 Hz | 0.033 Hz |
Note that PWM sysfs interface does not support setting of period more
than NSEC_PER_SEC / MAX_INT32 ~ 2 seconds, however this PWM controller
supports a period up to 30 seconds.
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/pwm-rcar.c')
0 files changed, 0 insertions, 0 deletions