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Message-ID: <046facdc-b558-146a-dcfd-0ed98bfeb517@phrozen.org>
Date: Wed, 21 Jun 2017 14:07:53 +0200
From: John Crispin <john@...ozen.org>
To: Zhi Mao <zhi.mao@...iatek.com>,
Thierry Reding <thierry.reding@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
linux-pwm@...r.kernel.org
Cc: zhenbao.liu@...iatek.com, devicetree@...r.kernel.org,
srv_heupstream@...iatek.com, sean.wang@...iatek.com,
linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
yt.shen@...iatek.com, yingjoe.chen@...iatek.com,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RESEND 2/4] pwm: mediatek: fix clk issue
Hi
comments inline
On 21/06/17 10:11, Zhi Mao wrote:
> 1.fix clock control
> - prepare top/main clk in mtk_pwm_probe() function,
> it will increase power consumption
> and in original code these clocks is only prepeare but never enabled
> - pwm clock should be enabled before setting pwm registers
> in function: mtk_pwm_config()
>
> 2.fix pwm source clock selection
> - in original code, the pwm output frequency is not correct
> when set bit<3>=1 to PWMCON register.
>
> Signed-off-by: Zhi Mao <zhi.mao@...iatek.com>
> ---
> drivers/pwm/pwm-mediatek.c | 69 +++++++++++++++++++++++++++-----------------
> 1 file changed, 43 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
> index 5c11bc7..c803ff6 100644
> --- a/drivers/pwm/pwm-mediatek.c
> +++ b/drivers/pwm/pwm-mediatek.c
> @@ -2,6 +2,7 @@
> * Mediatek Pulse Width Modulator driver
> *
> * Copyright (C) 2015 John Crispin <blogic@...nwrt.org>
> + * Copyright (C) 2017 Zhi Mao <zhi.mao@...iatek.com>
> *
> * This file is licensed under the terms of the GNU General Public
> * License version 2. This program is licensed "as is" without any
> @@ -61,6 +62,40 @@ static inline struct mtk_pwm_chip *to_mtk_pwm_chip(struct pwm_chip *chip)
> return container_of(chip, struct mtk_pwm_chip, chip);
> }
>
> +static int mtk_pwm_clk_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
> + int ret = 0;
> +
> + ret = clk_prepare_enable(pc->clks[MTK_CLK_TOP]);
> + if (ret < 0)
> + return ret;
> +
> + ret = clk_prepare_enable(pc->clks[MTK_CLK_MAIN]);
> + if (ret < 0) {
> + clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
> + if (ret < 0) {
> + clk_disable_unprepare(pc->clks[MTK_CLK_MAIN]);
> + clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
> + return ret;
> + }
> +
Rather than disabling the already prepared clks in each error path and
then returning, you should use goto err_clk_{top,main,pwm1} in the same
style as what this patch removes from mtk_pwm_probe()
> + return ret;
> +}
> +
> +static void mtk_pwm_clk_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
> +
> + clk_disable_unprepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
> + clk_disable_unprepare(pc->clks[MTK_CLK_MAIN]);
> + clk_disable_unprepare(pc->clks[MTK_CLK_TOP]);
> +}
> +
> static inline u32 mtk_pwm_readl(struct mtk_pwm_chip *chip, unsigned int num,
> unsigned int offset)
> {
> @@ -81,6 +116,8 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> struct clk *clk = pc->clks[MTK_CLK_PWM1 + pwm->hwpwm];
> u32 resolution, clkdiv = 0;
>
> + mtk_pwm_clk_enable(chip, pwm);
> +
> resolution = NSEC_PER_SEC / clk_get_rate(clk);
>
> while (period_ns / resolution > 8191) {
> @@ -91,10 +128,12 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> if (clkdiv > 7)
> return -EINVAL;
>
> - mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | BIT(3) | clkdiv);
> + mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
this chunk needs to go into its own patch
> mtk_pwm_writel(pc, pwm->hwpwm, PWMDWIDTH, period_ns / resolution);
> mtk_pwm_writel(pc, pwm->hwpwm, PWMTHRES, duty_ns / resolution);
>
> + mtk_pwm_clk_disable(chip, pwm);
> +
> return 0;
> }
>
> @@ -102,11 +141,8 @@ static int mtk_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> {
> struct mtk_pwm_chip *pc = to_mtk_pwm_chip(chip);
> u32 value;
> - int ret;
>
> - ret = clk_prepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
> - if (ret < 0)
> - return ret;
> + mtk_pwm_clk_enable(chip, pwm);
You need to check the error code here and return if clk enabling failed
>
> value = readl(pc->regs);
> value |= BIT(pwm->hwpwm);
> @@ -124,7 +160,7 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> value &= ~BIT(pwm->hwpwm);
> writel(value, pc->regs);
>
> - clk_unprepare(pc->clks[MTK_CLK_PWM1 + pwm->hwpwm]);
> + mtk_pwm_clk_disable(chip, pwm);
> }
>
> static const struct pwm_ops mtk_pwm_ops = {
> @@ -156,14 +192,6 @@ static int mtk_pwm_probe(struct platform_device *pdev)
> return PTR_ERR(pc->clks[i]);
> }
>
> - ret = clk_prepare(pc->clks[MTK_CLK_TOP]);
> - if (ret < 0)
> - return ret;
> -
> - ret = clk_prepare(pc->clks[MTK_CLK_MAIN]);
> - if (ret < 0)
> - goto disable_clk_top;
> -
> platform_set_drvdata(pdev, pc);
>
> pc->chip.dev = &pdev->dev;
> @@ -174,26 +202,15 @@ static int mtk_pwm_probe(struct platform_device *pdev)
> ret = pwmchip_add(&pc->chip);
> if (ret < 0) {
> dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> - goto disable_clk_main;
> + return ret;
> }
>
> return 0;
> -
> -disable_clk_main:
> - clk_unprepare(pc->clks[MTK_CLK_MAIN]);
> -disable_clk_top:
> - clk_unprepare(pc->clks[MTK_CLK_TOP]);
> -
> - return ret;
> }
>
> static int mtk_pwm_remove(struct platform_device *pdev)
> {
> struct mtk_pwm_chip *pc = platform_get_drvdata(pdev);
> - unsigned int i;
> -
> - for (i = 0; i < pc->chip.npwm; i++)
> - pwm_disable(&pc->chip.pwms[i]);
why are you removing this chunk ?
John
>
> return pwmchip_remove(&pc->chip);
> }
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