lkml.org 
[lkml]   [2021]   [Jul]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [v9 2/2] pwm: Add Aspeed ast2600 PWM support
Hello Billy,

On Fri, Jul 16, 2021 at 01:48:20AM +0000, Billy Tsai wrote:
> On 2021/7/15, 11:06 PM, "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>> wrote:
> > Another is: The PWM doesn't support duty_cycle 0, on such a request the
> > PWM is disabled which results in a constant inactive level.
>
> > (This is correct, is it? Or does it yield a constant 0 level?)
>
> Our pwm can support duty_cycle 0 by unset CLK_ENABLE.

This has a slightly different semantic though. Some consumer might
expect that the following sequence:

pwm_apply(mypwm, { .period = 10000, .duty_cycle = 10000, .enabled = true })
pwm_apply(mypwm, { .period = 10000, .duty_cycle = 0, .enabled = true })
pwm_apply(mypwm, { .period = 10000, .duty_cycle = 10000, .enabled = true })

results in the output being low for an integer multiple of 10 µs. This
isn't given with setting CLK_ENABLE to zero, is it? (I didn't recheck,
if the PWM doesn't complete periods on reconfiguration this doesn't
matter much though.)

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2021-07-16 09:10    [W:0.076 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site