On 09/20/2017 10:53 PM, Rob Herring wrote:

On Tue, Sep 19, 2017 at 11:01:02PM +0200, Jacek Anaszewski wrote:

quoted

Hi Pavel,

On 09/18/2017 10:54 PM, Pavel Machek wrote:

quoted

On Mon 2017-09-18 17:49:23, Sakari Ailus wrote:

quoted

Hi Pavel,

On Mon, Sep 18, 2017 at 12:56:55PM +0200, Pavel Machek wrote:

quoted

Hi!

quoted

Specify the exact label used if the label property is omitted in DT, as
well as use label in the example that conforms to LED device naming.

@@ -69,11 +73,11 @@ Example
 			flash-max-microamp = <320000>;
 			led-max-microamp = <60000>;
 			ams,input-max-microamp = <1750000>;
-			label = "as3645a:flash";
+			label = "as3645a:white:flash";
 		};
 		indicator@1 {
 			reg = <0x1>;
 			led-max-microamp = <10000>;
-			label = "as3645a:indicator";
+			label = "as3645a:red:indicator";
 		};
 	};

Ok, but userspace still has no chance to determine if this is flash
from main camera or flash for front camera; todays smartphones have
flashes on both cameras.

So.. Can I suggset as3645a:white:main_camera_flash or main_flash or
....?

If there's just a single one in the device, could you use that?

Even if we name this so for N9 (and N900), the application still would only
work with the two devices.

Well, I'd plan to name it on other devices, too.

quoted

My suggestion would be to look for a flash LED, and perhaps the maximum
current as well. That should generally work better than assumptions on the
label.

If you just look for flash LED, you don't know if it is front one or
back one. Its true that if you have just one flash it is usually on
the back camera, but you can't know if maybe driver is not available
for the main flash.

Lets get this right, please "main_camera_flash" is 12 bytes more than
"flash", and it saves application logic.. more than 12 bytes, I'm sure. 

What you are trying to introduce is yet another level of LED class
device naming standard, one level below devicename:colour:function.
It seems you want also to come up with the set of standarized LED
function names. This would certainly have to be covered for consistency.

I really dislike how this naming convention is used for label. label is 
supposed to be the phyically identifiable name. Having the devicename 
defeats that. Perhaps color, too. We'd be better off with a color 
property. It seems we're overloading the naming with too many things. 
Now we're adding device association.

Regarding devicename - there is indeed inconsistency in the way how LED
DT bindings use label, as some of them use it for defining full LED
class device name, and the rest fill only colour and function, leaving
addition of a devicename to the driver.

The problem is also in current definition of label in LED common
bindings documentation, which says:

"It has to uniquely identify a device, i.e. no other LED class device
can be assigned the same label."

In view of your above words this is not true, and we probably should
remove this sentence (it doesn't have DT maintainer ack btw).

I do want to see standard names though. On 96boards for example, there 
are defined LEDs and locations. The function on some are defined (e.g. 
WiFi/BT) and somewhat undefined on others (user{1-4}). I'd like to see 
the same label across all boards.

Currently we have following LED functions (obtained with
grep label Documentation/devicetree/bindings/leds/* | sed
s'/^.*label/label/g' | awk -F"=" '{print $2}' | sed '/^$/d' | sed
s'/.*:\(.*\)";/\1/' | sed '/^\s\{1,\}/d' | sort -u)

0
1
2
2g
3
4
5
6
7
adsl
alarm
alive
aux
broadband
chrg
dsl
flash
green
indicator
inet
keypad
phone
power
red
sata
sata0
sata1
tel
tv
upgrading
usb
usr0
usr1
usr35
wan
white
wireless
wps
yellow

By extracting numerical pattern names and replacing numbers with N
we're getting something like this:

N
Ng
colour
adsl
alarm
alive
aux
broadband
chrg
dsl
flash
indicator
inet
keypad
phone
power
sataN
tel
tv
upgrading
usb
usrN
wan
wireless
wps

Is this list something you'd like to see as a base of standard LED
functions? It seems that this list would have to be continuously
supplemented with new positions.

-- 
Best regards,
Jacek Anaszewski
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