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[93.42.71.246]) by smtp.gmail.com with ESMTPSA id cw5sm3412877ejc.74.2021.11.09.06.22.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Nov 2021 06:22:54 -0800 (PST) Date: Tue, 9 Nov 2021 15:22:53 +0100 From: Ansuel Smith To: Marek =?iso-8859-1?Q?Beh=FAn?= Cc: Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Jakub Kicinski , Rob Herring , Jonathan Corbet , Pavel Machek , John Crispin , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-leds@vger.kernel.org Subject: Re: [RFC PATCH v3 2/8] leds: add function to configure hardware controlled LED Message-ID: References: <20211109022608.11109-1-ansuelsmth@gmail.com> <20211109022608.11109-3-ansuelsmth@gmail.com> <20211109040103.7b56bf82@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211109040103.7b56bf82@thinkpad> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 09, 2021 at 04:01:03AM +0100, Marek Behún wrote: > Hello Ansuel, > > On Tue, 9 Nov 2021 03:26:02 +0100 > Ansuel Smith wrote: > > > Add hw_control_configure helper to configure how the LED should work in > > hardware mode. The function require to support the particular trigger and > > will use the passed flag to elaborate the data and apply the > > correct configuration. This function will then be used by the trigger to > > request and update hardware configuration. > > > > Signed-off-by: Ansuel Smith > > --- > > Documentation/leds/leds-class.rst | 25 ++++++++++++++++++++ > > include/linux/leds.h | 39 +++++++++++++++++++++++++++++++ > > 2 files changed, 64 insertions(+) > > > > diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst > > index 645940b78d81..efd2f68c46a7 100644 > > --- a/Documentation/leds/leds-class.rst > > +++ b/Documentation/leds/leds-class.rst > > @@ -198,6 +198,31 @@ With HARDWARE_CONTROLLED blink_mode hw_control_status/start/stop is optional > > and any software only trigger will reject activation as the LED supports only > > hardware mode. > > > > +A trigger once he declared support for hardware controlled blinks, will use the function > > +hw_control_configure() provided by the driver to check support for a particular blink mode. > > +This function passes as the first argument (flag) a u32 flag. > > +The second argument (cmd) of hw_control_configure() method can be used to do various > > +operations for the specific blink mode. We currently support ENABLE, DISABLE, READ, ZERO > > +and SUPPORTED to enable, disable, read the state of the blink mode, ask the LED > > +driver if it does supports the specific blink mode and to reset any blink mode active. > > + > > +In ENABLE/DISABLE hw_control_configure() should configure the LED to enable/disable the > > +requested blink mode (flag). > > +In READ hw_control_configure() should return 0 or 1 based on the status of the requested > > +blink mode (flag). > > +In SUPPORTED hw_control_configure() should return 0 or 1 if the LED driver supports the > > +requested blink mode (flags) or not. > > +In ZERO hw_control_configure() should return 0 with success operation or error. > > + > > +The unsigned long flag is specific to the trigger and change across them. It's in the LED > > +driver interest know how to elaborate this flag and to declare support for a > > +particular trigger. For this exact reason explicit support for the specific > > +trigger is mandatory or the driver returns -EOPNOTSUPP if asked to enter offload mode > > +with a not supported trigger. > > +If the driver returns -EOPNOTSUPP on hw_control_configure(), the trigger activation will > > +fail as the driver doesn't support that specific offload trigger or doesn't know > > +how to handle the provided flags. > > + > > Known Issues > > ============ > > > > diff --git a/include/linux/leds.h b/include/linux/leds.h > > index cf0c6005c297..00bc4d6ed7ca 100644 > > --- a/include/linux/leds.h > > +++ b/include/linux/leds.h > > @@ -73,6 +73,16 @@ enum led_blink_modes { > > SOFTWARE_HARDWARE_CONTROLLED, > > }; > > > > +#ifdef CONFIG_LEDS_HARDWARE_CONTROL > > +enum blink_mode_cmd { > > + BLINK_MODE_ENABLE, /* Enable the hardware blink mode */ > > + BLINK_MODE_DISABLE, /* Disable the hardware blink mode */ > > + BLINK_MODE_READ, /* Read the status of the hardware blink mode */ > > + BLINK_MODE_SUPPORTED, /* Ask the driver if the hardware blink mode is supported */ > > + BLINK_MODE_ZERO, /* Disable any hardware blink active */ > > +}; > > +#endif > > this is a strange proposal for the API. > > Anyway, led_classdev already has the blink_set() method, which is documented as > /* > * Activate hardware accelerated blink, delays are in milliseconds > * and if both are zero then a sensible default should be chosen. > * The call should adjust the timings in that case and if it can't > * match the values specified exactly. > * Deactivate blinking again when the brightness is set to LED_OFF > * via the brightness_set() callback. > */ > int (*blink_set)(struct led_classdev *led_cdev, > unsigned long *delay_on, > unsigned long *delay_off); > > So we already have a method to set hardware blkinking, we don't need > another one. > > Marek But that is about hardware blink, not a LED controlled by hardware based on some rules/modes. Doesn't really match the use for the hardware control. Blink_set makes the LED blink contantly at the declared delay. The blink_mode_cmd are used to request stuff to a LED in hardware mode. Doesn't seem correct to change/enhance the blink_set function with something that would do something completely different. -- Ansuel