On Fri, 3 Sep 2021, Pavel Machek wrote:

quoted

Player LEDs are commonly found on game controllers from Nintendo and Sony
to indicate a player ID across a number of LEDs. For example, "Player 2"
might be indicated as "-x--" on a device with 4 LEDs where "x" means on.

This patch introduces a new LED_FUNCTION_PLAYER to properly indicate
player LEDs from the kernel. Until now there was no good standard, which
resulted in inconsistent behavior across xpad, hid-sony, hid-wiimote and
other drivers. Moving forward new drivers should use LED_FUNCTION_PLAYER.

Note: management of Player IDs is left to user space, though a kernel
driver may pick a default value.

Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
---
 Documentation/leds/well-known-leds.txt | 14 ++++++++++++++
 include/dt-bindings/leds/common.h      |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/Documentation/leds/well-known-leds.txt b/Documentation/leds/well-known-leds.txt
index 4a8b9dc4bf52..2160382c86be 100644
--- a/Documentation/leds/well-known-leds.txt
+++ b/Documentation/leds/well-known-leds.txt

@@ -16,6 +16,20 @@ but then try the legacy ones, too.
 
 Notice there's a list of functions in include/dt-bindings/leds/common.h .
 
+* Gamepads and joysticks
+
+Game controllers may feature LEDs to indicate a player number. This is commonly
+used on game consoles in which multiple controllers can be connected to a system.
+The "player LEDs" are then programmed with a pattern to indicate a particular
+player. For example, a game controller with 4 LEDs, may be programmed with "x---"
+to indicate player 1, "-x--" to indicate player 2 etcetera where "x" means on.
+Input drivers can utilize the LED class to expose the individual player LEDs
+of a game controller using the function "player".

Thank you.

quoted

+Note: tracking and management of Player IDs is the responsibility of user space,
+though drivers may pick a default value.

I'm not sure we want kernel to do that.

quoted

+Good: "input*:*:player-{1,2,3,4,5}

This goes to the top.

quoted

+++ b/include/dt-bindings/leds/common.h

@@ -60,6 +60,9 @@
 #define LED_FUNCTION_MICMUTE "micmute"
 #define LED_FUNCTION_MUTE "mute"
 
+/* Used for player LEDs as found on game controllers from e.g. Nintendo, Sony. */
+#define LED_FUNCTION_PLAYER "player"
+

Let's not add this. For consistency we'd need defines player-1, player-2, ... We don't
need the define at all.

I guess this should go through my tree?

Once you provide your Reviewed/Acked-by, I can take it through my tree 
with the rest of the series.

Thanks,

-- 
Jiri Kosina
SUSE Labs