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Date: Sun, 6 Jun 2021 23:22:58 +0200
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Jitao Shi <jitao.shi@...iatek.com>
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
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.
> }
>
> -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.
> {
> 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);
> + 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().
> + 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
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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