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[2a01:c22:7b8d:b000::e63]) by smtp.googlemail.com with ESMTPSA id 4fb4d7f45d1cf-57d3048b923sm2726508a12.55.2024.06.22.12.15.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 22 Jun 2024 12:15:11 -0700 (PDT) From: Martin Blumenstingl To: linux-pwm@vger.kernel.org, ukleinek@kernel.org Cc: linux-kernel@vger.kernel.org, broonie@kernel.org, lgirdwood@gmail.com, Martin Blumenstingl , =?utf-8?q?Uwe_Kle?= =?utf-8?q?ine-K=C3=B6nig?= Subject: [RFC PATCH v2] regulator: pwm-regulator: Make assumptions about disabled PWM consistent Date: Sat, 22 Jun 2024 21:15:04 +0200 Message-ID: <20240622191504.38374-1-martin.blumenstingl@googlemail.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-pwm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Generally it's not known how a disabled PWM behaves. However if the bootloader hands over a disabled PWM that drives a regulator and it's claimed the regulator is enabled, then the most likely assumption is that the PWM emits the inactive level. This is represented by duty_cycle = 0 even for .polarity == PWM_POLARITY_INVERSED. Change the implementation to always use duty_cycle = 0, regardless of the polarity. Also update the code so it keeps a copy of the pwm_state around. Both of these changes result in the fact that the logic from pwm_regulator_init_boot_on() is much less complex and can be simplified to a point where the whole function is not needed anymore. Suggested-by: Uwe Kleine-König Signed-off-by: Martin Blumenstingl --- Changes from v1 [0] (which was sent by Uwe): - keep the struct pwm_state around to prevent a regression on Meson8b Odroid-C1 boards where just calling pwm_enable() without adjusting the duty_cycle to 0 would hang the board - I'm actively looking for input on the commit description and suggestions whether/why Fixes tags should be applied [0] https://lore.kernel.org/lkml/CAFBinCB+S1wOpD-fCbcTORqXSV00Sd7-1GHUKY+rO859_dkhOA@mail.gmail.com/T/ drivers/regulator/pwm-regulator.c | 119 ++++++++++++++---------------- 1 file changed, 55 insertions(+), 64 deletions(-) diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c index 7434b6b22d32..5ea354a0654a 100644 --- a/drivers/regulator/pwm-regulator.c +++ b/drivers/regulator/pwm-regulator.c @@ -41,6 +41,8 @@ struct pwm_regulator_data { /* Enable GPIO */ struct gpio_desc *enb_gpio; + + struct pwm_state pwm_state; }; struct pwm_voltages { @@ -48,18 +50,33 @@ struct pwm_voltages { unsigned int dutycycle; }; +static int pwm_regulator_apply_state(struct regulator_dev *rdev, + struct pwm_state *new_state) +{ + struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev); + int ret; + + ret = pwm_apply_might_sleep(drvdata->pwm, new_state); + if (ret) { + dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret); + return ret; + } + + drvdata->pwm_state = *new_state; + + return 0; +} + /* * Voltage table call-backs */ static void pwm_regulator_init_state(struct regulator_dev *rdev) { struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev); - struct pwm_state pwm_state; unsigned int dutycycle; int i; - pwm_get_state(drvdata->pwm, &pwm_state); - dutycycle = pwm_get_relative_duty_cycle(&pwm_state, 100); + dutycycle = pwm_get_relative_duty_cycle(&drvdata->pwm_state, 100); for (i = 0; i < rdev->desc->n_voltages; i++) { if (dutycycle == drvdata->duty_cycle_table[i].dutycycle) { @@ -83,18 +100,15 @@ static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev, unsigned selector) { struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev); - struct pwm_state pstate; + struct pwm_state pstate = drvdata->pwm_state; int ret; - pwm_init_state(drvdata->pwm, &pstate); pwm_set_relative_duty_cycle(&pstate, drvdata->duty_cycle_table[selector].dutycycle, 100); - ret = pwm_apply_might_sleep(drvdata->pwm, &pstate); - if (ret) { - dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret); + ret = pwm_regulator_apply_state(rdev, &pstate); + if (ret) return ret; - } drvdata->state = selector; @@ -115,17 +129,26 @@ static int pwm_regulator_list_voltage(struct regulator_dev *rdev, static int pwm_regulator_enable(struct regulator_dev *dev) { struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev); + struct pwm_state pstate = drvdata->pwm_state; gpiod_set_value_cansleep(drvdata->enb_gpio, 1); - return pwm_enable(drvdata->pwm); + pstate.enabled = true; + + return pwm_regulator_apply_state(dev, &pstate); } static int pwm_regulator_disable(struct regulator_dev *dev) { struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev); + struct pwm_state pstate = drvdata->pwm_state; + int ret; + + pstate.enabled = false; - pwm_disable(drvdata->pwm); + ret = pwm_regulator_apply_state(dev, &pstate); + if (ret) + return ret; gpiod_set_value_cansleep(drvdata->enb_gpio, 0); @@ -139,7 +162,7 @@ static int pwm_regulator_is_enabled(struct regulator_dev *dev) if (drvdata->enb_gpio && !gpiod_get_value_cansleep(drvdata->enb_gpio)) return false; - return pwm_is_enabled(drvdata->pwm); + return drvdata->pwm_state.enabled; } static int pwm_regulator_get_voltage(struct regulator_dev *rdev) @@ -151,20 +174,10 @@ static int pwm_regulator_get_voltage(struct regulator_dev *rdev) int min_uV = rdev->constraints->min_uV; int max_uV = rdev->constraints->max_uV; int diff_uV = max_uV - min_uV; - struct pwm_state pstate; unsigned int diff_duty; unsigned int voltage; - pwm_get_state(drvdata->pwm, &pstate); - - if (!pstate.enabled) { - if (pstate.polarity == PWM_POLARITY_INVERSED) - pstate.duty_cycle = pstate.period; - else - pstate.duty_cycle = 0; - } - - voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit); + voltage = pwm_get_relative_duty_cycle(&drvdata->pwm_state, duty_unit); if (voltage < min(max_uV_duty, min_uV_duty) || voltage > max(max_uV_duty, min_uV_duty)) return -ENOTRECOVERABLE; @@ -195,15 +208,12 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev, unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle; unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle; unsigned int duty_unit = drvdata->continuous.dutycycle_unit; + struct pwm_state pstate = drvdata->pwm_state; int min_uV = rdev->constraints->min_uV; int max_uV = rdev->constraints->max_uV; int diff_uV = max_uV - min_uV; - struct pwm_state pstate; unsigned int diff_duty; unsigned int dutycycle; - int ret; - - pwm_init_state(drvdata->pwm, &pstate); /* * The dutycycle for min_uV might be greater than the one for max_uV. @@ -226,13 +236,7 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev, pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit); - ret = pwm_apply_might_sleep(drvdata->pwm, &pstate); - if (ret) { - dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret); - return ret; - } - - return 0; + return pwm_regulator_apply_state(rdev, &pstate); } static const struct regulator_ops pwm_regulator_voltage_table_ops = { @@ -321,32 +325,6 @@ static int pwm_regulator_init_continuous(struct platform_device *pdev, return 0; } -static int pwm_regulator_init_boot_on(struct platform_device *pdev, - struct pwm_regulator_data *drvdata, - const struct regulator_init_data *init_data) -{ - struct pwm_state pstate; - - if (!init_data->constraints.boot_on || drvdata->enb_gpio) - return 0; - - pwm_get_state(drvdata->pwm, &pstate); - if (pstate.enabled) - return 0; - - /* - * Update the duty cycle so the output does not change - * when the regulator core enables the regulator (and - * thus the PWM channel). - */ - if (pstate.polarity == PWM_POLARITY_INVERSED) - pstate.duty_cycle = pstate.period; - else - pstate.duty_cycle = 0; - - return pwm_apply_might_sleep(drvdata->pwm, &pstate); -} - static int pwm_regulator_probe(struct platform_device *pdev) { const struct regulator_init_data *init_data; @@ -404,10 +382,23 @@ static int pwm_regulator_probe(struct platform_device *pdev) if (ret) return ret; - ret = pwm_regulator_init_boot_on(pdev, drvdata, init_data); - if (ret) - return dev_err_probe(&pdev->dev, ret, - "Failed to apply boot_on settings\n"); + pwm_init_state(drvdata->pwm, &drvdata->pwm_state); + + if (init_data->constraints.boot_on && !drvdata->enb_gpio && + !drvdata->pwm_state.enabled) + /* + * In general it's unknown what the output of a disabled PWM is. + * The only sane assumption here is it emits the inactive level + * which corresponds to duty_cycle = 0 (independent of the + * polarity). + * + * Update the duty cycle so the output does not change when the + * regulator core enables the regulator (and thus the PWM + * channel) and there's no change to the duty cycle because the + * voltage that is achieved with a disabled PWM is already the + * desired one. + */ + drvdata->pwm_state.duty_cycle = 0; regulator = devm_regulator_register(&pdev->dev, &drvdata->desc, &config);