Re: [PATCH RESEND] pwm: berlin: Don't use broken prescaler values

From: Thierry Reding
Date: Tue Jun 05 2018 - 05:10:21 EST


On Mon, Jun 04, 2018 at 02:32:41PM -0400, Thomas Hebb wrote:
> Six of the eight prescaler values available for Berlin PWM are not true
> prescalers but rather internal shifts that throw away the high bits of
> TCNT. Currently, we attempt to use those high bits, leading to erratic
> behavior. Restrict the prescaler configurations we select to only the
> two that respect the full range of TCNT.
>
> Tested on BG2CD.
>
> Signed-off-by: Thomas Hebb <tommyhebb@xxxxxxxxx>
> ---
> drivers/pwm/pwm-berlin.c | 45 ++++++++++++++++++++++------------------
> 1 file changed, 25 insertions(+), 20 deletions(-)

Antoine, Jisheng,

can you guys review this patch? I'm personally on the fence about this,
even if we can technically do the shift in software, I don't necessarily
see a reason why we can't "offload" to the hardware.

Thierry

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