Hi Boris,
> Hi Lukasz,
>
> On Mon, 26 Dec 2016 23:55:57 +0100
> Lukasz Majewski <l.majew...@majess.pl> wrote:
>
> > This commit provides apply() callback implementation for i.MX's
> > PWMv2.
> >
> > Suggested-by: Stefan Agner <ste...@agner.ch>
> > Suggested-by: Boris Brezillon <boris.brezil...@free-electrons.com>
> > Signed-off-by: Lukasz Majewski <l.majew...@majess.pl>
> > Reviewed-by: Boris Brezillon <boris.brezil...@free-electrons.com>
> > ---
> > Changes for v3:
> > - Remove ipg clock enable/disable functions
> >
> > Changes for v2:
> > - None
> > ---
> > drivers/pwm/pwm-imx.c | 70
> > +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed,
> > 70 insertions(+)
> >
> > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> > index ebe9b0c..cd53c05 100644
> > --- a/drivers/pwm/pwm-imx.c
> > +++ b/drivers/pwm/pwm-imx.c
> > @@ -159,6 +159,75 @@ static void imx_pwm_wait_fifo_slot(struct
> > pwm_chip *chip, }
> > }
> >
> > +static int imx_pwm_apply_v2(struct pwm_chip *chip, struct
> > pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + unsigned long period_cycles, duty_cycles, prescale;
> > + struct imx_chip *imx = to_imx_chip(chip);
> > + struct pwm_state cstate;
> > + unsigned long long c;
> > + u32 cr = 0;
> > + int ret;
> > +
> > + pwm_get_state(pwm, &cstate);
> > +
> > + c = clk_get_rate(imx->clk_per);
> > + c *= state->period;
> > +
> > + do_div(c, 1000000000);
> > + period_cycles = c;
> > +
> > + prescale = period_cycles / 0x10000 + 1;
> > +
> > + period_cycles /= prescale;
> > + c = (unsigned long long)period_cycles * state->duty_cycle;
> > + do_div(c, state->period);
> > + duty_cycles = c;
> > +
> > + /*
> > + * according to imx pwm RM, the real period value should be
> > + * PERIOD value in PWMPR plus 2.
> > + */
> > + if (period_cycles > 2)
> > + period_cycles -= 2;
> > + else
> > + period_cycles = 0;
> > +
> > + /* Enable the clock if the PWM is being enabled. */
> > + if (state->enabled && !cstate.enabled) {
> > + ret = clk_prepare_enable(imx->clk_per);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + /*
> > + * Wait for a free FIFO slot if the PWM is already
> > enabled, and flush
> > + * the FIFO if the PWM was disabled and is about to be
> > enabled.
> > + */
> > + if (cstate.enabled)
> > + imx_pwm_wait_fifo_slot(chip, pwm);
> > + else if (state->enabled)
> > + imx_pwm_sw_reset(chip);
> > +
> > + writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
> > + writel(period_cycles, imx->mmio_base + MX3_PWMPR);
> > +
> > + cr |= MX3_PWMCR_PRESCALER(prescale) |
> > + MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
> > + MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
> > +
> > + if (state->enabled)
> > + cr |= MX3_PWMCR_EN;
> > +
> > + writel(cr, imx->mmio_base + MX3_PWMCR);
> > +
> > + /* Disable the clock if the PWM is being disabled. */
> > + if (!state->enabled && cstate.enabled)
> > + clk_disable_unprepare(imx->clk_per);
> > +
> > + return 0;
> > +}
> > +
>
> Stefan suggested to rework this function to avoid unneeded
> duty/period calculation and reg write when disabling the PWM. Why
> didn't you send a v4 addressing that instead of resending the exact
> same v3?The discussion between you and Stefan was in this thread: http://patchwork.ozlabs.org/patch/689790/ Stefan proposed change, you replied with your concerns and that is all. No clear decision what to change until today when Stefan prepared separate (concise) patch (now I see what is the problem). > > Same goes for the regression introduced in patch 2: I think it's > better to keep things bisectable on all platforms (even if it > appeared to work by chance on imx7, it did work before this change). Could you be more specific about your idea to solve this problem? > > That's just my opinion, but when you get reviews on a patch series, > it's better to address them directly (especially when issues can be > easily fixed) than provide follow-up patches. I do not have iMX7 for testing/development, so I could not reproduce the error and address the issue directly. I can at best integrate Stefan's patch and hope to not introduce regression. Best regards, Łukasz Majewski > > Regards, > > Boris
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