From 998d189a817b8aae5b9e416c40dcb35b1fd79d3c Mon Sep 17 00:00:00 2001 From: =?utf8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Sat, 24 Aug 2019 02:10:39 +0200 Subject: [PATCH] pwm: atmel: Document known weaknesses of both hardware and software MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This documents the my findings while reading through the driver and the reference manual. Signed-off-by: Uwe Kleine-König Signed-off-by: Thierry Reding --- drivers/pwm/pwm-atmel.c | 10 ++++++++++ 1 file changed, 10 insertions(+) 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 -- 2.30.2