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Message-ID: <1623379063.24490.15.camel@mszsdaap41>
Date: Fri, 11 Jun 2021 10:37:43 +0800
From: Jitao Shi <jitao.shi@...iatek.com>
To: Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>
CC: Thierry Reding <thierry.reding@...il.com>,
Matthias Brugger <matthias.bgg@...il.com>,
<linux-pwm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-mediatek@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <srv_heupstream@...iatek.com>,
<yingjoe.chen@...iatek.com>, <eddie.huang@...iatek.com>,
<cawa.cheng@...iatek.com>, <bibby.hsieh@...iatek.com>,
<ck.hu@...iatek.com>, <stonea168@....com>,
<huijuan.xie@...iatek.com>
Subject: Re: [PATCH v4 3/3] pwm: mtk-disp: Switch to atomic API
On Sun, 2021-06-06 at 23:22 +0200, Uwe Kleine-König wrote:
> Hello,
>
> On Thu, Jun 03, 2021 at 06:05:31PM +0800, Jitao Shi wrote:
> > Convert the legacy api to atomic API.
> >
> > Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> > ---
> > drivers/pwm/pwm-mtk-disp.c | 78 ++++++++++++++++++++++++++++----------
> > 1 file changed, 59 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
> > index b87b3c00a685..d77348d0527c 100644
> > --- a/drivers/pwm/pwm-mtk-disp.c
> > +++ b/drivers/pwm/pwm-mtk-disp.c
> > @@ -67,8 +67,8 @@ static void mtk_disp_pwm_update_bits(struct mtk_disp_pwm *mdp, u32 offset,
> > writel(value, address);
> > }
> >
> > -static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > - int duty_ns, int period_ns)
> > +static int mtk_disp_pwm_config(struct pwm_chip *chip,
> > + const struct pwm_state *state)
> > {
> > struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
> > u32 clk_div, period, high_width, value;
> > @@ -102,7 +102,7 @@ static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1))
> > */
> > rate = clk_get_rate(mdp->clk_main);
> > - clk_div = div_u64(rate * period_ns, NSEC_PER_SEC) >>
> > + clk_div = div_u64(rate * state->period, NSEC_PER_SEC) >>
> > PWM_PERIOD_BIT_WIDTH;
> > if (clk_div > PWM_CLKDIV_MAX) {
> > dev_err(chip->dev, "clock rate is too high: rate = %d Hz\n",
> > @@ -114,11 +114,11 @@ static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > return -EINVAL;
> > }
> > div = NSEC_PER_SEC * (clk_div + 1);
> > - period = div64_u64(rate * period_ns, div);
> > + period = div64_u64(rate * state->period, div);
> > if (period > 0)
> > period--;
> >
> > - high_width = div64_u64(rate * duty_ns, div);
> > + high_width = div64_u64(rate * state->duty_cycle, div);
> > value = period | (high_width << PWM_HIGH_WIDTH_SHIFT);
> >
> > mtk_disp_pwm_update_bits(mdp, mdp->data->con0,
> > @@ -144,39 +144,79 @@ static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > mdp->data->con0_sel);
> > }
> >
> > + mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
> > + mdp->data->enable_mask);
> > + mdp->enabled = true;
> > +
> > return 0;
> > }
> >
> > -static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > + const struct pwm_state *state)
> > {
> > struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
> > - int err;
> >
> > - mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
> > - mdp->data->enable_mask);
> > - mdp->enabled = true;
> > + if (!state->enabled) {
> > + mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
> > + 0x0);
> >
> > - return 0;
> > + if (mdp->enabled) {
> > + clk_disable_unprepare(mdp->clk_mm);
> > + clk_disable_unprepare(mdp->clk_main);
> > + }
> > + mdp->enabled = false;
> > + return 0;
> > + }
> > +
> > + return mtk_disp_pwm_config(chip, state);
>
> Please unroll this function call. Having the old name is irritating.
I'll fix it next version.
Thanks for your review.
>
> > }
> >
> > -static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
> > + struct pwm_device *pwm,
> > + struct pwm_state *state)
>
> Adding .get_state() is great and warrants a separate patch.
>
I'll separate .get_state() next version.
Thanks for your review.
> > {
> > struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
> > + u32 clk_div, period, high_width, con0, con1;
> > + u64 rate;
> > + int err;
> >
> > - mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
> > - 0x0);
> > + if (!mdp->enabled) {
> > + err = clk_prepare_enable(mdp->clk_main);
> > + if (err < 0) {
> > + dev_err(chip->dev, "Can't enable mdp->clk_main: %d\n", err);
> > + return;
> > + }
> > + err = clk_prepare_enable(mdp->clk_mm);
> > + if (err < 0) {
> > + dev_err(chip->dev, "Can't enable mdp->clk_mm: %d\n", err);
> > + clk_disable_unprepare(mdp->clk_main);
> > + return;
> > + }
> > + }
> > +
> > + rate = clk_get_rate(mdp->clk_main);
> >
> > - if (mdp->enabled) {
> > + con0 = readl(mdp->base + mdp->data->con0);
> > + con1 = readl(mdp->base + mdp->data->con1);
> > +
> > + state->enabled = !!(con0 & BIT(0));
> > +
> > + clk_div = (con0 & PWM_CLKDIV_MASK) >> PWM_CLKDIV_SHIFT;
>
> clk_div = FIELD_GET(PWM_CLKDIV_MASK, con0);
I'll fix it next version.
>
> > + period = con1 & PWM_PERIOD_MASK;
> > + state->period = div_u64(period * (clk_div + 1) * NSEC_PER_SEC, rate);
>
> Can this multiplication overflow? Note this is a 32bit multiplication
> only. As .apply() uses round-down in the divisions (which is good)
> please round up there to get idempotency between .get_state() and
> .apply().
>
I'll fix it next version.
> > + high_width = (con1 & PWM_HIGH_WIDTH_MASK) >> PWM_HIGH_WIDTH_SHIFT;
> > + state->duty_cycle = div_u64(high_width * (clk_div + 1) * NSEC_PER_SEC,
> > + rate);
> > +
> > + if (!mdp->enabled) {
> > clk_disable_unprepare(mdp->clk_mm);
> > clk_disable_unprepare(mdp->clk_main);
> > }
> > - mdp->enabled = false;
> > }
>
> If my review comments contain too little details for you to understand,
> please feel free to ask. I'm willing to explain in more detail.
>
> Best regards
> Uwe
>
Thanks for your review.
Best Regards
Jitao
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