From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [PATCH 1/2] ACPI: Document how to refer to LEDs from remote nodes Date: Sun, 17 Sep 2017 18:57:09 +0200 Message-ID: <6baeee56-480b-00b9-4c84-e65dc7c42301@gmail.com> References: <20170915144052.25903-1-sakari.ailus@linux.intel.com> <20170915144052.25903-2-sakari.ailus@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Return-path: Received: from mail-wr0-f195.google.com ([209.85.128.195]:34030 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751466AbdIQQ6D (ORCPT ); Sun, 17 Sep 2017 12:58:03 -0400 In-Reply-To: <20170915144052.25903-2-sakari.ailus@linux.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Sakari Ailus , linux-leds@vger.kernel.org Cc: linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, mika.westerberg@intel.com, rafael@kernel.org Hi Sakari, Thanks for the patch. On 09/15/2017 04:40 PM, Sakari Ailus wrote: > Document referring to LEDs from remote device nodes, such as from camera > sensors. > > Signed-off-by: Sakari Ailus > --- > Documentation/acpi/dsd/leds.txt | 94 +++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 94 insertions(+) > create mode 100644 Documentation/acpi/dsd/leds.txt > > diff --git a/Documentation/acpi/dsd/leds.txt b/Documentation/acpi/dsd/leds.txt > new file mode 100644 > index 000000000000..894c82274f53 > --- /dev/null > +++ b/Documentation/acpi/dsd/leds.txt > @@ -0,0 +1,94 @@ > +Describing and referring to LEDs in ACPI > + > +Individual LEDs are described by hierarchical data extension [6] nodes > +under the device node, the LED driver chip. The "led" property in the > +LED specific nodes tells the numerical ID of each individual LED. The > +"led" property is used here in a similar fashion as the "reg" property > +in DT. [3] > + > +Referring to LEDs in Device tree is documented in [4], in "flash-leds" > +property documentation. In short, LEDs are directly referred to by > +using phandles. > + > +While Device tree allows referring to any node in the tree[1], in ACPI > +references are limited to device nodes only [2]. For this reason using > +the same mechanism on ACPI is not possible. > + > +ACPI allows (as does DT) using integer arguments after the reference. > +A combination of the LED driver device reference and an integer > +argument, referring to the "led" property of the relevant LED, are > +use to individual LEDs. s/are use/is used/ ? (in a sense "combination of ... and .. is used") s/to individual/to describe individual/ (or another verb, I'm not sure what exactly you intended it to be) The value of the LED property is a contract > +between the firmware and software, it uniquely identifies the LED > +driver outputs. > + > +An ASL example of a camera sensor device and a LED driver device for two > +LEDs. Objects not relevant for LEDs or the references to them have been > +omitted. > + > + Device (LED) > + { > + Name (_DSD, Package () { > + ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"), > + Package () { > + Package () { "led0", LED0 }, > + Package () { "led1", LED1 }, > + } > + }) > + Name (LED0, Package () { > + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), > + Package () { > + Package () { "led", 0 }, > + Package () { "flash-max-microamp", 1000000 }, > + Package () { "flash-timeout-us", 200000 }, > + Package () { "led-max-microamp", 100000 }, > + Package () { "label", "led:salama" }, > + } > + }) > + Name (LED1, Package () { > + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), > + Package () { > + Package () { "led", 1 }, > + Package () { "led-max-microamp", 10000 }, > + Package () { "label", "led:huomiovalo" }, > + } > + }) > + } > + > + Device (SEN) > + { > + Name (_DSD, Package () { > + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), > + Package () { > + Package () { > + "flash-leds", > + Package () { ^LED, 0, ^LED, 1 }, > + } > + } > + }) > + } > + > +where > + > + LED LED driver device > + LED0 First LED > + LED1 Second LED > + SEN Camera sensor device (or another device the LED is > + related to) > + > +[1] Device tree. , referenced 2016-10-03. > + > +[2] Advanced Configuration and Power Interface Specification. > + , > + referenced 2016-10-04. > + > +[3] Documentation/devicetree/bindings/leds/common.txt > + > +[4] Documentation/devicetree/bindings/media/video-interfaces.txt > + > +[5] Device Properties UUID For _DSD. > + , > + referenced 2016-10-04. > + > +[6] Hierarchical Data Extension UUID For _DSD. > + , > + referenced 2016-10-04. > -- Best regards, Jacek Anaszewski