From: Sean Young <sean@mess.org> To: linux-media@vger.kernel.org, linux-pwm@vger.kernel.org, "Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>, "Thierry Reding" <thierry.reding@gmail.com>, "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>, "Florian Fainelli" <florian.fainelli@broadcom.com>, "Broadcom internal kernel review list" <bcm-kernel-feedback-list@broadcom.com>, "Ray Jui" <rjui@broadcom.com>, "Scott Branden" <sbranden@broadcom.com> Cc: Sean Young <sean@mess.org>, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 3/4] pwm: bcm2835: allow pwm driver to be used in atomic context Date: Sat, 18 Nov 2023 16:16:19 +0000 [thread overview] Message-ID: <25749f50c404a26fa43dda031ed1c6cc562e18ce.1700323916.git.sean@mess.org> (raw) In-Reply-To: <cover.1700323916.git.sean@mess.org> clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent rate changes using clk_rate_exclusive_get(). Signed-off-by: Sean Young <sean@mess.org> --- drivers/pwm/pwm-bcm2835.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c index 9777babd5b95c..52748194a3dad 100644 --- a/drivers/pwm/pwm-bcm2835.c +++ b/drivers/pwm/pwm-bcm2835.c @@ -28,6 +28,7 @@ struct bcm2835_pwm { struct device *dev; void __iomem *base; struct clk *clk; + unsigned long rate; }; static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) @@ -63,17 +64,11 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); - unsigned long rate = clk_get_rate(pc->clk); unsigned long long period_cycles; u64 max_period; u32 val; - if (!rate) { - dev_err(pc->dev, "failed to get clock rate\n"); - return -EINVAL; - } - /* * period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the @@ -88,13 +83,13 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1 */ - max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, rate) - 1; + max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1; if (state->period > max_period) return -EINVAL; /* set period */ - period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, NSEC_PER_SEC); + period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * pc->rate, NSEC_PER_SEC); /* don't accept a period that is too small */ if (period_cycles < PERIOD_MIN) @@ -103,7 +98,7 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, writel(period_cycles, pc->base + PERIOD(pwm->hwpwm)); /* set duty cycle */ - val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC); + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC); writel(val, pc->base + DUTY(pwm->hwpwm)); /* set polarity */ @@ -151,14 +146,29 @@ static int bcm2835_pwm_probe(struct platform_device *pdev) return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk), "clock not found\n"); + ret = clk_rate_exclusive_get(pc->clk); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "fail to get exclusive rate\n"); + + pc->rate = clk_get_rate(pc->clk); + if (!pc->rate) { + clk_rate_exclusive_put(pc->clk); + return dev_err_probe(&pdev->dev, -EINVAL, + "failed to get clock rate\n"); + } + pc->chip.dev = &pdev->dev; pc->chip.ops = &bcm2835_pwm_ops; + pc->chip.atomic = true; pc->chip.npwm = 2; ret = devm_pwmchip_add(&pdev->dev, &pc->chip); - if (ret < 0) + if (ret < 0) { + clk_rate_exclusive_put(pc->clk); return dev_err_probe(&pdev->dev, ret, "failed to add pwmchip\n"); + } return 0; } @@ -167,6 +177,7 @@ static int bcm2835_pwm_suspend(struct device *dev) { struct bcm2835_pwm *pc = dev_get_drvdata(dev); + clk_rate_exclusive_put(pc->clk); clk_disable_unprepare(pc->clk); return 0; -- 2.42.1
WARNING: multiple messages have this Message-ID (diff)
From: Sean Young <sean@mess.org> To: linux-media@vger.kernel.org, linux-pwm@vger.kernel.org, "Ivaylo Dimitrov" <ivo.g.dimitrov.75@gmail.com>, "Thierry Reding" <thierry.reding@gmail.com>, "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>, "Florian Fainelli" <florian.fainelli@broadcom.com>, "Broadcom internal kernel review list" <bcm-kernel-feedback-list@broadcom.com>, "Ray Jui" <rjui@broadcom.com>, "Scott Branden" <sbranden@broadcom.com> Cc: Sean Young <sean@mess.org>, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 3/4] pwm: bcm2835: allow pwm driver to be used in atomic context Date: Sat, 18 Nov 2023 16:16:19 +0000 [thread overview] Message-ID: <25749f50c404a26fa43dda031ed1c6cc562e18ce.1700323916.git.sean@mess.org> (raw) In-Reply-To: <cover.1700323916.git.sean@mess.org> clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent rate changes using clk_rate_exclusive_get(). Signed-off-by: Sean Young <sean@mess.org> --- drivers/pwm/pwm-bcm2835.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c index 9777babd5b95c..52748194a3dad 100644 --- a/drivers/pwm/pwm-bcm2835.c +++ b/drivers/pwm/pwm-bcm2835.c @@ -28,6 +28,7 @@ struct bcm2835_pwm { struct device *dev; void __iomem *base; struct clk *clk; + unsigned long rate; }; static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) @@ -63,17 +64,11 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, { struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); - unsigned long rate = clk_get_rate(pc->clk); unsigned long long period_cycles; u64 max_period; u32 val; - if (!rate) { - dev_err(pc->dev, "failed to get clock rate\n"); - return -EINVAL; - } - /* * period_cycles must be a 32 bit value, so period * rate / NSEC_PER_SEC * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the @@ -88,13 +83,13 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) - 1 */ - max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, rate) - 1; + max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1; if (state->period > max_period) return -EINVAL; /* set period */ - period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, NSEC_PER_SEC); + period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * pc->rate, NSEC_PER_SEC); /* don't accept a period that is too small */ if (period_cycles < PERIOD_MIN) @@ -103,7 +98,7 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, writel(period_cycles, pc->base + PERIOD(pwm->hwpwm)); /* set duty cycle */ - val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC); + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC); writel(val, pc->base + DUTY(pwm->hwpwm)); /* set polarity */ @@ -151,14 +146,29 @@ static int bcm2835_pwm_probe(struct platform_device *pdev) return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk), "clock not found\n"); + ret = clk_rate_exclusive_get(pc->clk); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "fail to get exclusive rate\n"); + + pc->rate = clk_get_rate(pc->clk); + if (!pc->rate) { + clk_rate_exclusive_put(pc->clk); + return dev_err_probe(&pdev->dev, -EINVAL, + "failed to get clock rate\n"); + } + pc->chip.dev = &pdev->dev; pc->chip.ops = &bcm2835_pwm_ops; + pc->chip.atomic = true; pc->chip.npwm = 2; ret = devm_pwmchip_add(&pdev->dev, &pc->chip); - if (ret < 0) + if (ret < 0) { + clk_rate_exclusive_put(pc->clk); return dev_err_probe(&pdev->dev, ret, "failed to add pwmchip\n"); + } return 0; } @@ -167,6 +177,7 @@ static int bcm2835_pwm_suspend(struct device *dev) { struct bcm2835_pwm *pc = dev_get_drvdata(dev); + clk_rate_exclusive_put(pc->clk); clk_disable_unprepare(pc->clk); return 0; -- 2.42.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-11-18 16:17 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-18 16:16 [PATCH v5 0/4] Improve pwm-ir-tx precision Sean Young 2023-11-18 16:16 ` [PATCH v5 1/4] pwm: rename pwm_apply_state() to pwm_apply_cansleep() Sean Young 2023-11-18 16:16 ` Sean Young 2023-11-18 16:16 ` [Intel-gfx] " Sean Young 2023-11-18 16:16 ` Sean Young 2023-11-23 15:15 ` Lee Jones 2023-11-23 15:15 ` Lee Jones 2023-11-23 15:15 ` [Intel-gfx] " Lee Jones 2023-11-23 15:15 ` Lee Jones 2023-11-24 13:31 ` Thierry Reding 2023-11-24 13:31 ` [Intel-gfx] " Thierry Reding 2023-11-24 13:31 ` Thierry Reding 2023-11-24 13:31 ` Thierry Reding 2023-11-29 9:08 ` Sean Young 2023-11-29 9:08 ` Sean Young 2023-11-29 9:08 ` [Intel-gfx] " Sean Young 2023-11-29 9:08 ` Sean Young 2023-11-18 16:16 ` [PATCH v5 2/4] pwm: make it possible to apply pwm changes in atomic context Sean Young 2023-11-24 13:36 ` Thierry Reding 2023-11-29 9:07 ` Sean Young 2023-11-18 16:16 ` Sean Young [this message] 2023-11-18 16:16 ` [PATCH v5 3/4] pwm: bcm2835: allow pwm driver to be used " Sean Young 2023-11-18 16:16 ` [PATCH v5 4/4] media: pwm-ir-tx: trigger edges from hrtimer interrupt context Sean Young 2023-11-22 8:51 ` [PATCH v5 0/4] Improve pwm-ir-tx precision Sean Young 2023-11-23 16:58 ` Uwe Kleine-König 2023-11-24 8:37 ` Sean Young
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