Hi Jacek,
Thanks for the feedback.
On Sun, Sep 17, 2017 at 06:57:09PM +0200, Jacek Anaszewski wrote:
> 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 <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> > 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)
I'll use "is used to identify", for this is what it essentially is for.
>
> 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. <URL:http://www.devicetree.org>, referenced 2016-10-03.
> > +
> > +[2] Advanced Configuration and Power Interface Specification.
> > + <URL:http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf>,
> > + 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.
> > + <URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>,
> > + referenced 2016-10-04.
> > +
> > +[6] Hierarchical Data Extension UUID For _DSD.
> > + <URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf>,
> > + referenced 2016-10-04.
> >
>
> --
> Best regards,
> Jacek Anaszewski
--
Sakari Ailus
e-mail: sakari.ailus@xxxxxx
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