Re: [PATCH v3 04/15] pwm: lpss: Add range limit check for the base_unit register value

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Hi,

On 7/7/20 9:09 PM, Uwe Kleine-König wrote:
Hello Hans,

On Tue, Jul 07, 2020 at 07:31:29PM +0200, Hans de Goede wrote:
On 7/7/20 9:34 AM, Uwe Kleine-König wrote:
On Mon, Jul 06, 2020 at 10:53:08PM +0200, Hans de Goede wrote:
But if we do then I think closest to the truth would be:

state->period     = UINT_MAX;
state->duty_cycle = 0;

I'd say state->period = 1 & state->duty_cycle = 0 is a better
representation.

But that would suggest the output is configured for an
infinitely high output frequency, but the frequency is
actually 0, the reason why get_state needs to treat a
base_unit val of 0 special at all is to avoid a division
by 0, and in math dividing by 0 gives infinite, isn't
UINT_MAX a better way to represent infinity ?

Given that duty_cycle is 0, how can to tell anything about the period
when only seeing the signal (= a constant low)?

Given that (ideally) a period is completed when pwm_apply_state() is
called, a short period is much more sensible.

Ok, I will add a patch to v4 of the patch-set to adjust the pwm-lpss
driver's get_state method accordingly.

Regards,

Hans




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