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[86.9.19.6]) by smtp.gmail.com with ESMTPSA id n1sm13156524wrx.39.2019.07.15.02.24.02 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 15 Jul 2019 02:24:02 -0700 (PDT) Date: Mon, 15 Jul 2019 10:24:00 +0100 From: Daniel Thompson To: Jean-Jacques Hiblot Cc: Dan Murphy , jacek.anaszewski@gmail.com, pavel@ucw.cz, robh+dt@kernel.org, mark.rutland@arm.com, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH 1/2] leds: Add control of the voltage/current regulator to the LED core Message-ID: <20190715092400.sedjumqkecglheyu@holly.lan> References: <20190708103547.23528-1-jjhiblot@ti.com> <20190708103547.23528-2-jjhiblot@ti.com> <56d16260-ff82-3439-4c1f-2a3a1552bc7d@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org On Mon, Jul 15, 2019 at 11:01:29AM +0200, Jean-Jacques Hiblot wrote: > Hi Dan, > > On 12/07/2019 20:49, Dan Murphy wrote: > > JJ > > > > On 7/8/19 5:35 AM, Jean-Jacques Hiblot wrote: > > > A LED is usually powered by a voltage/current regulator. Let the LED > > > core > > 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 | 10 ++++++++ > > >   drivers/leds/led-core.c  | 53 +++++++++++++++++++++++++++++++++++++--- > > >   include/linux/leds.h     |  4 +++ > > >   3 files changed, 64 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c > > > index 4793e77808e2..e01b2d982564 100644 > > > --- a/drivers/leds/led-class.c > > > +++ b/drivers/leds/led-class.c > > > @@ -17,6 +17,7 @@ > > >   #include > > >   #include > > >   #include > > > +#include > > > > What if you move this to leds.h so core and class can both include it. > > > > > > >   #include > > >   #include "leds.h" > > >   @@ -272,6 +273,15 @@ int of_led_classdev_register(struct device > > > *parent, struct device_node *np, > > >           dev_warn(parent, "Led %s renamed to %s due to name collision", > > >                   led_cdev->name, dev_name(led_cdev->dev)); > > >   +    led_cdev->regulator = devm_regulator_get(led_cdev->dev, "power"); > > > > Is the regulator always going to be called power? > > Actually in the dts, that will be "power-supply". I lacked the imagination > to come up with a better name. > > > > > > > > +    if (IS_ERR(led_cdev->regulator)) { > > > +        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(led_cdev->regulator); > > > > This is listed as optional in the DT doc.  This appears to be required. > > The regulator core will provide a dummy regulator if none is given in the > device tree. I would rather have an error in that case, but that is not how > it works. If you actively wanted to get -ENODEV back when there is no regulator then you can use devm_regulator_get_optional() for that. However perhaps be careful what you wish for. If you use get_optional() then you will have to sprinkle NULL or IS_ERR() checks everywhere. I'd favour using the current approach! Daniel. > > > > > > I prefer to keep it optional.  Many LED drivers are connected to fixed > > non-managed supplies. > > > > > +    } > > > + > > >       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 7107cd7e87cf..139de6b08cad 100644 > > > --- a/drivers/leds/led-core.c > > > +++ b/drivers/leds/led-core.c > > > @@ -16,6 +16,7 @@ > > >   #include > > >   #include > > >   #include "leds.h" > > > +#include > > >     DECLARE_RWSEM(leds_list_lock); > > >   EXPORT_SYMBOL_GPL(leds_list_lock); > > > @@ -23,6 +24,31 @@ EXPORT_SYMBOL_GPL(leds_list_lock); > > >   LIST_HEAD(leds_list); > > >   EXPORT_SYMBOL_GPL(leds_list); > > >   +static bool __led_need_regulator_update(struct led_classdev > > > *led_cdev, > > > +                    int brightness) > > > +{ > > > +    bool new_regulator_state = (brightness != LED_OFF); > > > + > > > +    return led_cdev->regulator_state != new_regulator_state; > > > +} > > > + > > > +static int __led_handle_regulator(struct led_classdev *led_cdev, > > > +                int brightness) > > > +{ > > > +    if (__led_need_regulator_update(led_cdev, brightness)) { > > > +        int ret; > > > > Prefer to this to be moved up. > ok > > > > > + > > > +        if (brightness != LED_OFF) > > > +            ret = regulator_enable(led_cdev->regulator); > > > +        else > > > +            ret = regulator_disable(led_cdev->regulator); > > > +        if (ret) > > > +            return ret; > > new line > > > +        led_cdev->regulator_state = (brightness != LED_OFF); > > > +    } > > > +    return 0; > > > +} > > > + > > >   static int __led_set_brightness(struct led_classdev *led_cdev, > > >                   enum led_brightness value) > > >   { > > > @@ -80,6 +106,7 @@ static void led_timer_function(struct timer_list *t) > > >       } > > >         led_set_brightness_nosleep(led_cdev, brightness); > > > +    __led_handle_regulator(led_cdev, brightness); > > > > Again this seems to indicate that the regulator is a required property > > for the LEDs > > > > This needs to be made optional.  And the same comment through out for > > every call. > > > > > > >         /* Return in next iteration if led is in one-shot mode and > > > we are in > > >        * the final blink state so that the led is toggled each > > > delay_on + > > > @@ -115,6 +142,8 @@ static void set_brightness_delayed(struct > > > work_struct *ws) > > >       if (ret == -ENOTSUPP) > > >           ret = __led_set_brightness_blocking(led_cdev, > > >                       led_cdev->delayed_set_value); > > > +    __led_handle_regulator(led_cdev, led_cdev->delayed_set_value); > > > + > > >       if (ret < 0 && > > >           /* LED HW might have been unplugged, therefore don't warn */ > > >           !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) && > > > @@ -141,6 +170,7 @@ static void led_set_software_blink(struct > > > led_classdev *led_cdev, > > >       /* never on - just set to off */ > > >       if (!delay_on) { > > >           led_set_brightness_nosleep(led_cdev, LED_OFF); > > > +        __led_handle_regulator(led_cdev, LED_OFF); > > >           return; > > >       } > > >   @@ -148,6 +178,7 @@ static void led_set_software_blink(struct > > > led_classdev *led_cdev, > > >       if (!delay_off) { > > >           led_set_brightness_nosleep(led_cdev, > > >                          led_cdev->blink_brightness); > > > +        __led_handle_regulator(led_cdev, led_cdev->blink_brightness); > > >           return; > > >       } > > >   @@ -256,8 +287,14 @@ 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)) > > > -        return; > > > +    if (!__led_set_brightness(led_cdev, value)) { > > > +        /* > > > +         * if regulator state doesn't need to be changed, that is all/ > > > +         * Otherwise delegate the change to a work queue > > > +         */ > > > +        if (!__led_need_regulator_update(led_cdev, value)) > > > +            return; > > > +    } > > >         /* If brightness setting can sleep, delegate it to a work > > > queue task */ > > >       led_cdev->delayed_set_value = value; > > > @@ -280,6 +317,8 @@ EXPORT_SYMBOL_GPL(led_set_brightness_nosleep); > > >   int led_set_brightness_sync(struct led_classdev *led_cdev, > > >                   enum led_brightness value) > > >   { > > > +    int ret; > > > + > > >       if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) > > >           return -EBUSY; > > >   @@ -288,7 +327,15 @@ int led_set_brightness_sync(struct > > > led_classdev *led_cdev, > > >       if (led_cdev->flags & LED_SUSPENDED) > > >           return 0; > > >   -    return __led_set_brightness_blocking(led_cdev, > > > led_cdev->brightness); > > > +    ret = __led_set_brightness_blocking(led_cdev, > > > led_cdev->brightness); > > > +    if (ret) > > > +        return ret; > > > + > > > +    ret = __led_handle_regulator(led_cdev, led_cdev->brightness); > > > > Can't you just return here? > > ok > > > thanks for the review > > JJ > > > > > Dan > > > > > +    if (ret) > > > +        return ret; > > > + > > > +    return 0; > > >   } > > >   EXPORT_SYMBOL_GPL(led_set_brightness_sync); > > >   diff --git a/include/linux/leds.h b/include/linux/leds.h > > > index 9b2bf574a17a..bee8e3f8dddd 100644 > > > --- a/include/linux/leds.h > > > +++ b/include/linux/leds.h > > > @@ -123,6 +123,10 @@ struct led_classdev { > > >         /* Ensures consistent access to the LED Flash Class device */ > > >       struct mutex        led_access; > > > + > > > +    /* regulator */ > > > +    struct regulator    *regulator; > > > +    bool            regulator_state; > > >   }; > > >     extern int of_led_classdev_register(struct device *parent,