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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>
This commit is contained in:
Uwe Kleine-König 2019-08-24 02:10:39 +02:00 committed by Thierry Reding
parent 2101c878f7
commit 998d189a81
1 changed files with 10 additions and 0 deletions
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10
drivers/pwm/pwm-atmel.c
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@ -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>