On Thu, Jul 09, 2020 at 05:47:59PM +0200, Hans de Goede wrote:
Hi,
On 7/9/20 4:50 PM, Andy Shevchenko wrote:
On Wed, Jul 08, 2020 at 11:14:22PM +0200, Hans de Goede wrote:
The datasheet specifies that programming the base_unit part of the ctrl register to 0 results in a contineous low signal.
Adjust the get_state method to reflect this by setting pwm_state.period to 1 and duty_cycle to 0.
...
- if (freq == 0) {
/* In this case the PWM outputs a continous low signal */
state->period = 1;I guess this should be something like half of the range (so base unit calc will give 128). Because with period = 1 (too small) it will give too small base unit (if apply) and as a result we get high frequency pulses.
You are right, that if after this the user only changes the duty-cycle things will work very poorly, we will end up with a base_unit value of e.g 65535 and then have almost no duty-cycle resolution at all.
Is this a problem of the consumer that we don't need to solve? Are there known consumers running into this problem?
pwm_lpss_prepare() is buggy here, a request for a too low period should be refused.
Best regards Uwe