Re: [PATCH RESEND 2/4] pwm: mediatek: fix clk issue
From: John Crispin <john@phrozen.org>
Date: 2017-06-21 12:07:58
Also in:
linux-arm-kernel, linux-mediatek, linux-pwm, lkml
Hi comments inline On 21/06/17 10:11, Zhi Mao wrote:
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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@mediatek.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@openwrt.org> + * Copyright (C) 2017 Zhi Mao <zhi.mao@mediatek.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()
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+ 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
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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
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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); }