On Wed, Jan 13, 2021 at 08:36:12AM +0200, Baruch Siach wrote:
> Hi Uwe,
>
> On Mon, Jan 11 2021, Uwe Kleine-König wrote:
> > $Subject ~= s/get_state/.get_state/ ?
>
> Ack.
>
> > On Mon, Jan 11, 2021 at 01:17:02PM +0200, Baruch Siach wrote:
> >> The period is the sum of on and off values.
> >>
> >> Reported-by: Russell King <linux@xxxxxxxxxxxxxxx>
> >> Fixes: 757642f9a584e ("gpio: mvebu: Add limited PWM support")
> >> Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
> >> ---
> >> drivers/gpio/gpio-mvebu.c | 19 ++++++++-----------
> >> 1 file changed, 8 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> >> index 672681a976f5..a912a8fed197 100644
> >> --- a/drivers/gpio/gpio-mvebu.c
> >> +++ b/drivers/gpio/gpio-mvebu.c
> >> @@ -676,20 +676,17 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
> >> else
> >> state->duty_cycle = 1;
> >>
> >> + val = (unsigned long long) u; /* on duration */
> >> regmap_read(mvpwm->regs, mvebu_pwmreg_blink_off_duration(mvpwm), &u);
> >> - val = (unsigned long long) u * NSEC_PER_SEC;
> >> + val += (unsigned long long) u; /* period = on + off duration */
> >> + val *= NSEC_PER_SEC;
> >> do_div(val, mvpwm->clk_rate);
> >> - if (val < state->duty_cycle) {
> >> + if (val > UINT_MAX)
> >> + state->period = UINT_MAX;
> >> + else if (val)
> >> + state->period = val;
> >> + else
> >> state->period = 1;
> >> - } else {
> >> - val -= state->duty_cycle;
> >> - if (val > UINT_MAX)
> >> - state->period = UINT_MAX;
> >> - else if (val)
> >> - state->period = val;
> >> - else
> >> - state->period = 1;
> >> - }
> >
> > The patch looks good, the patch description could be a bit more verbose.
> > Something like:
> >
> > Calculate the period as
> >
> > ($on + $off) / clkrate
> >
> > instead of
> >
> > $off / clkrate - $on / clkrate
> >
> > .
>
> I take this to refer to the next patch (2/5). This patch changes from
> buggy
>
> $on / clkrate
No, the previous calculation had
- val -= state->duty_cycle;
which accounts for "- $on / clkrate".
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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