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[95.49.139.84]) by smtp.gmail.com with ESMTPSA id j205sm732333wma.42.2020.03.09.12.42.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Mar 2020 12:42:37 -0700 (PDT) Subject: Re: [RFC PATCH] leds: pwm: add flag to start without PWM init To: Denis Osterland-Heim , "dmurphy@ti.com" , "pavel@ucw.cz" , "mark.rutland@arm.com" , "robh+dt@kernel.org" Cc: "linux-kernel@vger.kernel.org" , "linux-leds@vger.kernel.org" , "devicetree@vger.kernel.org" References: <20200309082218.13263-1-Denis.Osterland@diehl.com> From: Jacek Anaszewski Autocrypt: addr=jacek.anaszewski@gmail.com; prefer-encrypt=mutual; keydata= xsFNBFWjfaEBEADd66EQbd6yd8YjG0kbEDT2QIkx8C7BqMXR8AdmA1OMApbfSvEZFT1D/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/sVSKT2TwARAQABzS1KYWNlayBBbmFz emV3c2tpIDxqYWNlay5hbmFzemV3c2tpQGdtYWlsLmNvbT7Cwa8EEwEIAEICGwMHCwkIBwMC AQYVCAIJCgsDFgIBAh4BAheAAhkBFiEEvx38ClaPBfeVdXCQvWpQHLeLfCYFAl5O5twFCRIR arsAIQkQvWpQHLeLfCYWIQS/HfwKVo8F95V1cJC9alAct4t8JhIgEACtWz3zR5uxaU/GozHh iZfiyUTomQpGNvAtjjZE6UKO/cKusCcvOv0FZbfGDajcMIU8f3FUxJdybrY86KJ9a3tOddal KtB2of3/Ot/EIQjpQb28iLoY8AWnf9G4LQZtoXHiUcOAVPkKgCFnz1IENK3uvyCB9c9//KhE cRZkeAIE2sTmcI4k7/dNHpRI4nha/ZytPwTdM3BjAfxxQI5nMLptm1ksEBI7W1SDOnY3dG2J QWmqpxIefjgyiy0aU+jAw1x3RdZrokVD8OCJiJM8+Z36imarEzqIRQLh+sDNLfV3wEaBn/HU 0Vj6VrRyW2K0jAYToRFD3Ay/eGSfOOAEr/LoMr3NBTDkRLEWdOozllOwADEY9wH0BLHMp2WI hXGOStNiroIEhW2/E0udFJo9b3VoOWKWl+zcUP/keLxVUCXhpmeS7VpSkqsrCVqTVkEc8AXq xhJXeIQJC/XRpCYFc3pFUlVCFViF1ZU2OzE8TndRzzD8e/9ETrJ1GAYa78tNopYhY6AbGlv4 U01nIC93bK07O4IhtBAKsiUz3JPX/KA/dXJOC86qP373cVWVYPvZW+KOya9/7rz0MGR1az9G HqJB7q7DVcCQKt9Egae/goznnXbET6ivCNKbqkH3n/JpiPIxkaXVrbn3QlVtzYpROsS/pCOp 5Evig7kql5L0aYJIZs4zBFsKioYWCSsGAQQB2kcPAQEHQFCKEG5pCgebryz66pTa9eAo+r8y TkMEEnG8UR5oWFt3wsIbBBgBCAAgFiEEvx38ClaPBfeVdXCQvWpQHLeLfCYFAlsKioYCGwIA rwkQvWpQHLeLfCaNIAQZFggAHRYhBBTDHErITmX+em3wBGIQbFEb9KXbBQJbCoqGACEJEGIQ bFEb9KXbFiEEFMMcSshOZf56bfAEYhBsURv0pdvELgD/U+y3/hsz0bIjMQJY0LLxM/rFY9Vz 1L43+lQHXjL3MPsA/1lNm5sailsY7aFBVJxAzTa8ZAGWBdVaGo6KCvimDB8GFiEEvx38ClaP BfeVdXCQvWpQHLeLfCbuOg/+PH6gY6Z1GiCzuYb/8f7D0NOcF8+md+R6KKiQZij/6G5Y7lXQ Bz21Opl4Vz/+39i5gmfBa9LRHH4ovR9Pd6H0FCjju4XjIOJkiJYs2HgCCm6nUxRJWzPgyMPS VbqCG2ctwaUiChUdbS+09bWb2MBNjIlI4b8wLWIOtxhyn25Vifm0p+QR5A2ym4bqJJ9LSre1 qM8qdPWcnExPFU4PZFYQgZ9pX1Jyui73ZUP94L7/wg1GyJZL3ePeE4ogBXldE0g0Wq3ORqA9 gA/yvrCSyNKOHTV9JMGnnPGN+wjBYMPMOuqDPC/zcK+stdFXc6UbUM1QNgDnaomvjuloflAx aYdblM26gFfypvpFb8czcPM+BP6X6vWk+Mw9+8vW3tyK9lSg+43OjIWlBGPpO9aLZsYYxAqv J5iSxcbbOLb5q8wWct6U7EZ1RnuOfVInoBttrlYvdWtcI/5NQTptkuB/DyRhrxBJc/fKzJ4w jS2ikcWe0FnxrQpcE2yqoUIFaZMdd/Cx9bRWAGZG087t5dUHJuMnVVcpHZFnHBKr8ag1eH/K tFdDFtyln5A/f9O22xsV0pyJni7e2z7lTBitrQFG69vnVGJlHbBE2dR4GddZqAlVOUbtEcE7 /aMk4TrCtx0IyOzQiLA81aaJWhkD3fRO8cDlR4YQ3F0aqjYy8x1EnnhhohHOwU0EVaN9oQEQ 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 +Pi0GjVpEYQVWfm0PTCxNPOzOzGR4QB3BNFvABEBAAHCwZMEGAEIACYCGwwWIQS/HfwKVo8F 95V1cJC9alAct4t8JgUCXk7nGAUJEhFq9wAhCRC9alAct4t8JhYhBL8d/ApWjwX3lXVwkL1q UBy3i3wmVBwP/RNNux3dC513quZ0hFyU6ZDTxbiafprLN2PXhmLslxPktJgW/xO5xp16OXkW YgNI/TKxj3+oSu+MhEAhAFA2urFWHyqedfqdndQTzbv4yqNuyhGupzPBWNSqqJ2NwKJc9f2R wqYTXVYIO+6KLa32rpl7xvJISkx06s70lItFJjyOf6Hn1y5RBMwQN9hP2YxLhYNO3rmlNSVy 7Z/r95lZTDnnUCuxBZxnjx/pMHJ8LZtKY0t7D0esA+zYGUrmoAGUpNWEBP+uSL+f8rhjSAL0 HgoRL39ixg5Bm0MzJn9z3or++Pl5bRnSvHy6OKh7rzTjCwaGoZD+6LHBwPFPlmInX1H+yHrX lu1uPAdqG5xcsZAZFTxBRMEnYu1yYebDSA9x+iulggMZQcWC2GvHCaKIpKcFY8XCxk7Hbl5c 8hcPKWOy16NLO6Y66Ws4kMedXuNUHe4zBLVlRbcYUdgT9Brw8nxmxu3KhEVsJkwOpXLUDuzo hQNfg9em95lpAK+VOTocke8PSESy3GbEtmoMueW3caSeDHb5dRP6WrndaYhEOzAA/KjuPU7J LMXOABOMIq+R38y7e2B3TnVDCrccdZDseFPUWmH0cGCGihH/j2UZG+PImrSDCh3h5MedVHGo sI62tmWm0q6lrljwSZmMZ30w1QaGmdFpI3Q6V+nZ7TZldI3x Message-ID: <68c56b10-7ebb-2bb4-213f-400e3f99ac40@gmail.com> Date: Mon, 9 Mar 2020 20:42:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200309082218.13263-1-Denis.Osterland@diehl.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-leds-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org Hi Denis, There is already a property for that purpose: default-state = "keep"; Please just use it instead. Best regards, Jacek Anaszewski On 3/9/20 9:24 AM, Denis Osterland-Heim wrote: > This patch add "pwm,uninitalized" devicetree flag support to pwm > leds, which allows to defer pwm init to first use of led. > > This allows to configure the PWM early in bootloader to let the LED > blink until an application in Linux userspace set something different. > > Signed-off-by: Denis Osterland-Heim > --- > Hi, > > I want to ask if such a patch is intresting for mainline and > if it is woth to think about how to represent this state to user space. > > Regards Denis > > Documentation/devicetree/bindings/leds/leds-pwm.txt | 1 + > drivers/leds/leds-pwm.c | 10 ++++++++-- > include/linux/leds_pwm.h | 1 + > 3 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/leds/leds-pwm.txt b/Documentation/devicetree/bindings/leds/leds-pwm.txt > index 6c6583c35f2f..4f58df631fc9 100644 > --- a/Documentation/devicetree/bindings/leds/leds-pwm.txt > +++ b/Documentation/devicetree/bindings/leds/leds-pwm.txt > @@ -19,6 +19,7 @@ LED sub-node properties: > see Documentation/devicetree/bindings/leds/common.txt > - linux,default-trigger : (optional) > see Documentation/devicetree/bindings/leds/common.txt > +- pwm,uninitalized : defer PWM init to first brightness change of led > > Example: > > diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c > index 8b6965a563e9..02c90f05602a 100644 > --- a/drivers/leds/leds-pwm.c > +++ b/drivers/leds/leds-pwm.c > @@ -97,7 +97,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, > * FIXME: pwm_apply_args() should be removed when switching to the > * atomic PWM API. > */ > - pwm_apply_args(led_data->pwm); > + if (!led->pwm_uninitialized) > + pwm_apply_args(led_data->pwm); > > pwm_get_args(led_data->pwm, &pargs); > > @@ -108,7 +109,9 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, > ret = devm_led_classdev_register(dev, &led_data->cdev); > if (ret == 0) { > priv->num_leds++; > - led_pwm_set(&led_data->cdev, led_data->cdev.brightness); > + if (!led->pwm_uninitialized) > + led_pwm_set(&led_data->cdev, > + led_data->cdev.brightness); > } else { > dev_err(dev, "failed to register PWM led for %s: %d\n", > led->name, ret); > @@ -143,6 +146,9 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv) > fwnode_property_read_u32(fwnode, "max-brightness", > &led.max_brightness); > > + led.pwm_uninitialized = fwnode_property_read_bool(fwnode, > + "pwm,uninitialized"); > + > ret = led_pwm_add(dev, priv, &led, fwnode); > if (ret) { > fwnode_handle_put(fwnode); > diff --git a/include/linux/leds_pwm.h b/include/linux/leds_pwm.h > index 93d101d28943..0b04dfd43654 100644 > --- a/include/linux/leds_pwm.h > +++ b/include/linux/leds_pwm.h > @@ -10,6 +10,7 @@ struct led_pwm { > const char *default_trigger; > unsigned pwm_id __deprecated; > u8 active_low; > + u8 pwm_uninitialized; > unsigned max_brightness; > unsigned pwm_period_ns; > }; >