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[83.28.60.157]) by smtp.gmail.com with ESMTPSA id k9sm4461578wrd.7.2019.09.24.11.58.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Sep 2019 11:58:03 -0700 (PDT) Subject: Re: [PATCH v5 3/3] leds: Add control of the voltage/current regulator to the LED core To: Jean-Jacques Hiblot , pavel@ucw.cz, daniel.thompson@linaro.org Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, dmurphy@ti.com, tomi.valkeinen@ti.com References: <20190923102059.17818-1-jjhiblot@ti.com> <20190923102059.17818-4-jjhiblot@ti.com> From: Jacek Anaszewski Openpgp: preference=signencrypt Autocrypt: addr=jacek.anaszewski@gmail.com; prefer-encrypt=mutual; keydata= mQINBFWjfaEBEADd66EQbd6yd8YjG0kbEDT2QIkx8C7BqMXR8AdmA1OMApbfSvEZFT1D/ECR eWFBS8XtApKQx1xAs1j5z70k3zebk2eeNs5ahxi6vM4Qh89vBM46biSKeeX5fLcv7asmGb/a FnHPAfQaKFyG/Bj9V+//ef67hpjJWR3s74C6LZCFLcbZM0z/wTH+baA5Jwcnqr4h/ygosvhP X3gkRzJLSFYekmEv+WHieeKXLrJdsUPUvPJTZtvi3ELUxHNOZwX2oRJStWpmL2QGMwPokRNQ 29GvnueQdQrIl2ylhul6TSrClMrKZqOajDFng7TLgvNfyVZE8WQwmrkTrdzBLfu3kScjE14Q Volq8OtQpTsw5570D4plVKh2ahlhrwXdneSot0STk9Dh1grEB/Jfw8dknvqkdjALUrrM45eF FM4FSMxIlNV8WxueHDss9vXRbCUxzGw37Ck9JWYo0EpcpcvwPf33yntYCbnt+RQRjv7vy3w5 osVwRR4hpbL/fWt1AnZ+RvbP4kYSptOCPQ+Pp1tCw16BOaPjtlqSTcrlD2fo2IbaB5D21SUa IsdZ/XkD+V2S9jCrN1yyK2iKgxtDoUkWiqlfRgH2Ep1tZtb4NLF/S0oCr7rNLO7WbqLZQh1q ShfZR16h7YW//1/NFwnyCVaG1CP/L/io719dPWgEd/sVSKT2TwARAQABtC1KYWNlayBBbmFz emV3c2tpIDxqYWNlay5hbmFzemV3c2tpQGdtYWlsLmNvbT6JAlgEEwEIAEICGwMHCwkIBwMC AQYVCAIJCgsDFgIBAh4BAheABQkJZgNMFiEEvx38ClaPBfeVdXCQvWpQHLeLfCYFAl05/9sC GQEACgkQvWpQHLeLfCarMQ/9FN/WqJdN2tf6xkP0RFyS4ft0sT04zkOCFfOMxs8mZ+KZoMU+ X3a+fEppDL7xgRFpHyGaEel7lSi1eqtzsqZ5JiHbDS1Ht1G8TtATb8q8id68qeSeW2mfzaLQ 98NPELGfUXFoUqUQkG5z2p92UrGF4Muj1vOIW93pwvE4uDpNsl+jriwHomLtjIUoZtIRjGfZ RCyUQI0vi5LYzXCebuzAjGD7Jh2YAp7fDGrv3qTq8sX+DUJ4H/+I8PiL+jXKkEeppqIhlBJJ l4WcgggMu3c2uljYDuqRYghte33BXyCPAocfO2/sN+yJRUTVuRFlOxUk4srz/W8SQDwOAwtK V7TzdyF1/jOGBxWwS13EjMb4u3XwPMzcPlEQNdIqz76NFmJ99xYEvgkAmFmRioxuBTRv8Fs1 c1jQ00WWJ5vezqY6lccdDroPalXWeFzfPjIhKbV3LAYTlqv0It75GW9+0TBhPqdTM15DrCVX B7Ues7UnD5FBtWwewTnwr+cu8te449VDMzN2I+a9YKJ1s6uZmzh5HnuKn6tAfGyQh8MujSOM lZrNHrRsIsLXOjeGVa84Qk/watEcOoyQ7d+YaVosU0OCZl0GldvbGp1z2u8cd2N/HJ7dAgFh Q7dtGXmdXpt2WKQvTvQXhIrCWVQErNYbDZDD2V0TZtlPBaZP4fkUDkvH+Sy5Ag0EVaN9oQEQ AMPNymBNoCWc13U6qOztXrIKBVsLGZXq/yOaR2n7gFbFACD0TU7XuH2UcnwvNR+uQFwSrRqa EczX2V6iIy2CITXKg5Yvg12yn09gTmafuoIyKoU16XvC3aZQQ2Bn3LO2sRP0j/NuMD9GlO37 pHCVRpI2DPxFE39TMm1PLbHnDG8+lZql+dpNwWw8dDaRgyXx2Le542CcTBT52VCeeWDtqd2M wOr4LioYlfGfAqmwcwucBdTEBUxklQaOR3VbJQx6ntI2oDOBlNGvjnVDzZe+iREd5l40l+Oj TaiWvBGXkv6OI+wx5TFPp+BM6ATU+6UzFRTUWbj+LqVA/JMqYHQp04Y4H5GtjbHCa8abRvBw IKEvpwTyWZlfXPtp8gRlNmxYn6gQlTyEZAWodXwE7CE+KxNnq7bPHeLvrSn8bLNK682PoTGr 0Y00bguYLfyvEwuDYek1/h9YSXtHaCR3CEj4LU1B561G1j7FVaeYbX9bKBAoy/GxAW8J5O1n mmw7FnkSHuwO/QDe0COoO0QZ620Cf9IBWYHW4m2M2yh5981lUaiMcNM2kPgsJFYloFo2XGn6 lWU9BrWjEoNDhHZtF+yaPEuwjZo6x/3E2Tu3E5Jj0VpVcE9U1Zq/fquDY79l2RJn5ENogOs5 +Pi0GjVpEYQVWfm0PTCxNPOzOzGR4QB3BNFvABEBAAGJAiUEGAEIAA8FAlWjfaECGwwFCQlm AYAACgkQvWpQHLeLfCZqGxAAlWBWVvjU6xj70GwengiqYZwmW1i8gfS4TNibQT/KRq0zkBnE wgKwXRbVoW38pYVuGa5x/JDQMJDrLAJ0wrCOS3XxbSHCWOl/k2ZD9OaxUeXq6N+OmGTzfrYv PUvWS1Hy04q9AD1dIaMNruZQmvnRfkOk2UDncDIg0166/NTHiYI09H5mpWGpHn/2aT6dmpVw uoM9/rHlF5s5qAAo95tZ0QW2BtIceG9/rbYlL57waSMPF49awvwLQX5RhWoF8mPS5LsBrXXK hmizIsn40tLbi2RtWjzDWgZYitqmmqijeCnDvISN4qJ/nCLO4DjiSGs59w5HR+l0nwePDhOC A4RYZqS1e2Clx1VSkDXFpL3egabcIsqK7CZ6a21r8lXVpo4RnMlQsmXZTnRx4SajFvX7PrRg /02C811fLfh2r5O5if8sKQ6BKKlHpuuioqfj/w9z3B0aQ71e4n1zNJBO1kcdznikPLAbr7jG gkBUXT1yJiwpTfRQr5y2Uo12IJsKxohnNFVYtK8X/R6S0deKPjrZWvAkllgIPcHjMi2Va8yw KTj/JgcpUO5KN906Pf7ywZISe7Kbcc/qnE0YjPPSqFOvoeZvHe6EZCMW9+xZsaipvlqpByQV UHnVg09K9YFvjUBsBPdC8ef6YwgfR9o6AnPmxl0oMUIXkCCC5c99fzJY/k+JAq0EGAEIACAW IQS/HfwKVo8F95V1cJC9alAct4t8JgUCWwqKhgIbAgCBCRC9alAct4t8JnYgBBkWCAAdFiEE FMMcSshOZf56bfAEYhBsURv0pdsFAlsKioYACgkQYhBsURv0pdvELgD/U+y3/hsz0bIjMQJY 0LLxM/rFY9Vz1L43+lQHXjL3MPsA/1lNm5sailsY7aFBVJxAzTa8ZAGWBdVaGo6KCvimDB8G 7joP/jx+oGOmdRogs7mG//H+w9DTnBfPpnfkeiiokGYo/+huWO5V0Ac9tTqZeFc//t/YuYJn wWvS0Rx+KL0fT3eh9BQo47uF4yDiZIiWLNh4Agpup1MUSVsz4MjD0lW6ghtnLcGlIgoVHW0v tPW1m9jATYyJSOG/MC1iDrcYcp9uVYn5tKfkEeQNspuG6iSfS0q3tajPKnT1nJxMTxVOD2RW EIGfaV9Scrou92VD/eC+/8INRsiWS93j3hOKIAV5XRNINFqtzkagPYAP8r6wksjSjh01fSTB p5zxjfsIwWDDzDrqgzwv83CvrLXRV3OlG1DNUDYA52qJr47paH5QMWmHW5TNuoBX8qb6RW/H M3DzPgT+l+r1pPjMPfvL1t7civZUoPuNzoyFpQRj6TvWi2bGGMQKryeYksXG2zi2+avMFnLe lOxGdUZ7jn1SJ6Abba5WL3VrXCP+TUE6bZLgfw8kYa8QSXP3ysyeMI0topHFntBZ8a0KXBNs qqFCBWmTHXfwsfW0VgBmRtPO7eXVBybjJ1VXKR2RZxwSq/GoNXh/yrRXQxbcpZ+QP3/Tttsb FdKciZ4u3ts+5UwYra0BRuvb51RiZR2wRNnUeBnXWagJVTlG7RHBO/2jJOE6wrcdCMjs0Iiw PNWmiVoZA930TvHA5UeGENxdGqo2MvMdRJ54YaIR Message-ID: <3e648fab-638f-4aa0-dda9-8ddba6562751@gmail.com> Date: Tue, 24 Sep 2019 20:58:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20190923102059.17818-4-jjhiblot@ti.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Hi Jean, Thank you for the patch. I must say I'm not a big fan of this change. It adds a bunch of code to the LED core and gives small functionality in a reward. It may also influence maximum software blinking rate, so I'd rather avoid calling regulator_enable/disable when timer trigger is set. It will of course require more code. Since AFAIR Pavel was original proponent of this change then I'd like to see his opinion before we move on to discussing possible improvements to this patch. Best regards, Jacek Anaszewski On 9/23/19 12:20 PM, Jean-Jacques Hiblot wrote: > A LED is usually powered by a voltage/current regulator. Let the LED core > know about it. This allows the LED core to turn on or off the power supply > as needed. > > Signed-off-by: Jean-Jacques Hiblot > --- > drivers/leds/led-class.c | 17 +++++++++++ > drivers/leds/led-core.c | 65 ++++++++++++++++++++++++++++++++++++++-- > drivers/leds/leds.h | 3 ++ > include/linux/leds.h | 5 ++++ > 4 files changed, 88 insertions(+), 2 deletions(-) > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > index e11177d77b4c..d122b6982efd 100644 > --- a/drivers/leds/led-class.c > +++ b/drivers/leds/led-class.c > @@ -352,6 +352,7 @@ int led_classdev_register_ext(struct device *parent, > char final_name[LED_MAX_NAME_SIZE]; > const char *proposed_name = composed_name; > int ret; > + struct regulator *regulator; > > if (init_data) { > if (init_data->devname_mandatory && !init_data->devicename) { > @@ -387,6 +388,22 @@ int led_classdev_register_ext(struct device *parent, > dev_warn(parent, "Led %s renamed to %s due to name collision", > led_cdev->name, dev_name(led_cdev->dev)); > > + regulator = devm_regulator_get_optional(led_cdev->dev, "power"); > + if (IS_ERR(regulator)) { > + if (regulator != ERR_PTR(-ENODEV)) { > + dev_err(led_cdev->dev, "Cannot get the power supply for %s\n", > + led_cdev->name); > + device_unregister(led_cdev->dev); > + mutex_unlock(&led_cdev->led_access); > + return PTR_ERR(regulator); > + } > + led_cdev->regulator = NULL; > + } else { > + led_cdev->regulator = regulator; > + led_cdev->regulator_state = REG_OFF; > + atomic_set(&led_cdev->target_regulator_state, REG_UNKNOWN); > + } > + > if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) { > ret = led_add_brightness_hw_changed(led_cdev); > if (ret) { > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > index d318f9b0382d..155a158c7b8d 100644 > --- a/drivers/leds/led-core.c > +++ b/drivers/leds/led-core.c > @@ -37,6 +37,43 @@ const char * const led_colors[LED_COLOR_ID_MAX] = { > }; > EXPORT_SYMBOL_GPL(led_colors); > > +static int __led_handle_regulator(struct led_classdev *led_cdev) > +{ > + int rc; > + int target_state = led_cdev->delayed_set_value ? REG_ON : REG_OFF; > + > + if (!led_cdev->regulator) > + return 0; > + > + /* > + * if the current regulator state is not the target state, we > + * need to update it. > + * note: No need for spinlock or atomic here because > + * led_cdev->regulator_state is modified only in the context of > + * the worqueue > + */ > + if (led_cdev->regulator_state != target_state) { > + > + if (target_state == REG_ON) > + rc = regulator_enable(led_cdev->regulator); > + else > + rc = regulator_disable(led_cdev->regulator); > + if (rc) { > + /* > + * If something went wrong with the regulator update, > + * Make sure that led_set_brightness_nosleep() assume > + * that the regultor is in the right state. > + */ > + atomic_set(&led_cdev->target_regulator_state, > + REG_UNKNOWN); > + return rc; > + } > + > + led_cdev->regulator_state = target_state; > + } > + return 0; > +} > + > static int __led_set_brightness(struct led_classdev *led_cdev, > enum led_brightness value) > { > @@ -135,6 +172,11 @@ static void set_brightness_delayed(struct work_struct *ws) > (led_cdev->flags & LED_HW_PLUGGABLE))) > dev_err(led_cdev->dev, > "Setting an LED's brightness failed (%d)\n", ret); > + > + ret = __led_handle_regulator(led_cdev); > + if (ret) > + dev_err(led_cdev->dev, > + "Updating regulator state failed (%d)\n", ret); > } > > static void led_set_software_blink(struct led_classdev *led_cdev, > @@ -269,8 +311,27 @@ EXPORT_SYMBOL_GPL(led_set_brightness); > void led_set_brightness_nopm(struct led_classdev *led_cdev, > enum led_brightness value) > { > - /* Use brightness_set op if available, it is guaranteed not to sleep */ > - if (!__led_set_brightness(led_cdev, value)) > + bool update_regulator = false; > + int old, new; > + > + if (led_cdev->regulator) { > + /* > + * Check if the regulator need to be updated. > + * We use an atomic here because multiple threads could > + * be calling this function at the same time. Using > + * atomic_xchg() ensures the consistency between > + * target_regulator_state, value and update_regulator > + */ > + new = !!value; > + old = atomic_xchg(&led_cdev->target_regulator_state, new); > + update_regulator = (old != new); > + } > + > + /* > + * If regulator state doesn't need to be changed, use brightness_set > + * op if available, it is guaranteed not to sleep > + */ > + if (!update_regulator && !__led_set_brightness(led_cdev, value)) > return; > > /* If brightness setting can sleep, delegate it to a work queue task */ > diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h > index 0b577cece8f7..02f261ce77f2 100644 > --- a/drivers/leds/leds.h > +++ b/drivers/leds/leds.h > @@ -11,6 +11,9 @@ > > #include > #include > +#include > + > +enum { REG_OFF = 0, REG_ON, REG_UNKNOWN }; > > static inline int led_get_brightness(struct led_classdev *led_cdev) > { > diff --git a/include/linux/leds.h b/include/linux/leds.h > index 88bf2ceaabe6..8ce7cf937192 100644 > --- a/include/linux/leds.h > +++ b/include/linux/leds.h > @@ -149,6 +149,11 @@ struct led_classdev { > > /* Ensures consistent access to the LED Flash Class device */ > struct mutex led_access; > + > + /* regulator */ > + struct regulator *regulator; > + int regulator_state; > + atomic_t target_regulator_state; > }; > > /** >