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[83.31.83.198]) by smtp.gmail.com with ESMTPSA id y3sm9533818wmg.2.2019.10.02.10.46.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Oct 2019 10:46:43 -0700 (PDT) Subject: Re: [PATCH -next 2/2] leds: add /sys/class/leds//current-trigger To: Dan Murphy , Akinobu Mita , linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Pavel Machek References: <1570029181-11102-1-git-send-email-akinobu.mita@gmail.com> <1570029181-11102-3-git-send-email-akinobu.mita@gmail.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: <589ba4d7-31f5-c789-d5ca-c13650cf5b03@gmail.com> Date: Wed, 2 Oct 2019 19:46:40 +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: 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 Dan, On 10/2/19 5:47 PM, Dan Murphy wrote: > Akinobu > > On 10/2/19 10:13 AM, Akinobu Mita wrote: >> Reading /sys/class/leds//trigger returns all available LED triggers. >> However, this violates the "one value per file" rule of sysfs. >> >> This provides /sys/class/leds//current-trigger which is almost >> identical to /sys/class/leds//trigger. The only difference is that >> 'current-trigger' only shows the current trigger name. >> >> This new file follows the "one value per file" rule of sysfs. >> We can find all available LED triggers by listing the >> /sys/devices/virtual/led-trigger/ directory. >> >> Cc: Greg Kroah-Hartman >> Cc: "Rafael J. Wysocki" >> Cc: Jacek Anaszewski >> Cc: Pavel Machek >> Cc: Dan Murphy >> Signed-off-by: Akinobu Mita >> --- >> Documentation/ABI/testing/sysfs-class-led | 13 +++++++++++ >> drivers/leds/led-class.c | 10 ++++++++ >> drivers/leds/led-triggers.c | 38 >> +++++++++++++++++++++++++++---- >> drivers/leds/leds.h | 5 ++++ >> 4 files changed, 62 insertions(+), 4 deletions(-) >> >> diff --git a/Documentation/ABI/testing/sysfs-class-led >> b/Documentation/ABI/testing/sysfs-class-led >> index 5f67f7a..fdfed3f 100644 >> --- a/Documentation/ABI/testing/sysfs-class-led >> +++ b/Documentation/ABI/testing/sysfs-class-led >> @@ -61,3 +61,16 @@ Description: >> gpio and backlight triggers. In case of the backlight trigger, >> it is useful when driving a LED which is intended to indicate >> a device in a standby like state. >> + >> +What: /sys/class/leds//current-trigger >> +Date: September 2019 >> +KernelVersion: 5.5 >> +Contact: linux-leds@vger.kernel.org >> +Description: >> + Set the trigger for this LED. A trigger is a kernel based source >> + of LED events. >> + Writing the trigger name to this file will change the current >> + trigger. Trigger specific parameters can appear in >> + /sys/class/leds/ once a given trigger is selected. For >> + their documentation see sysfs-class-led-trigger-*. >> + Reading this file will return the current LED trigger name. > > Why do we need this new file can't we just update the current trigger > file implementation? We can't change existing ABI. It doesn't matter if it is documented or not - it's in place for very long time and you can't guarantee there are no users relying on triggers file show format. > I don't see any documentation that states that the read of the trigger > file will print a list of known triggers. > > And writing to the trigger file still works so I would think the _show > just needs to be fixed. > > Besides this patch does not fix the issue in the commit message that the > trigger file still violates the one value per file rule. > > Dan > > -- Best regards, Jacek Anaszewski