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| author | Uwe Kleine-König <uwe@kleine-koenig.org> | 2019-08-24 02:10:39 +0200 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2020-01-08 13:44:08 +0100 |
| commit | 998d189a817b8aae5b9e416c40dcb35b1fd79d3c (patch) | |
| tree | e62725126ccdd290ed9d65d237ae6818db84026f /drivers/pwm/pwm-atmel.c | |
| parent | pwm: atmel: Replace loop in prescale calculation by ad-hoc calculation (diff) | |
| download | linux-998d189a817b8aae5b9e416c40dcb35b1fd79d3c.tar.xz linux-998d189a817b8aae5b9e416c40dcb35b1fd79d3c.zip | |
pwm: atmel: Document known weaknesses of both hardware and software
This documents the my findings while reading through the driver and the
reference manual.
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/pwm-atmel.c')
| -rw-r--r-- | drivers/pwm/pwm-atmel.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c index c9fdf1671bb3..3ff3c171437e 100644 --- a/drivers/pwm/pwm-atmel.c +++ b/drivers/pwm/pwm-atmel.c @@ -7,6 +7,16 @@ * * Links to reference manuals for the supported PWM chips can be found in * Documentation/arm/microchip.rst. + * + * Limitations: + * - Periods start with the inactive level. + * - Hardware has to be stopped in general to update settings. + * + * Software bugs/possible improvements: + * - When atmel_pwm_apply() is called with state->enabled=false a change in + * state->polarity isn't honored. + * - Instead of sleeping to wait for a completed period, the interrupt + * functionality could be used. */ #include <linux/clk.h> |