On Fri, 26 Jul 2024 14:57:03 -0700
Dmitry Torokhov [off-list ref] wrote:

On Fri, Jul 26, 2024 at 02:57:03PM -0700, Dmitry Torokhov wrote:

quoted

Hi Qiang,

On Fri, Jul 26, 2024 at 06:27:30PM +0800, Qiang Ma wrote:

quoted

After we turn on the keyboard CAPSL LED and let the system
suspend, the keyboard LED is not off, and the kernel log is as
follows:

[  185.987574] i8042: [44060] ed -> i8042 (kbd-data)
[  185.988057] i8042: [44061] ** <- i8042 (interrupt, 0, 1)
[  185.988067] i8042: [44061] 04 -> i8042 (kbd-data)
[  185.988248] i8042: [44061] ** <- i8042 (interrupt, 0, 1)

The log shows that after the command 0xed is sent, the data
sent is 0x04 instead of 0x00.

Solution:
Add a bitmap variable ledon in the atkbd structure, and then set
ledon according to code-value in the event, in the atkbd_set_leds
function, first look at the value of lenon, if it is 0, there is
no need to look at the value of dev->led, otherwise, Need to look
at dev->led to determine the keyboard LED on/off.

I am not sure why duplicating input_dev->led which is supposed to
record which LEDs are currently active on an input device would
solve the issue. Could you please explain?

Ah, OK, I see it now. We do not actually toggle input_dev->led when
suspending, so atkbd uses wrong data to determine the LED state.

Yes, that's true.

quoted

The input core is supposed to turn off all LEDs on suspend. This
happens in input_dev_toggle() which is called from
input_dev_suspend(). It iterates over all LEDs on a device and
turns off active ones one by one.

I think what happens here is we are running afoul of the throttling
done in atkbd (see atkbd_schedule_event_work), and it does not
actually turn off all LEDs in time. But on the other hand
atkbd_cleanup() (which is called to suspend the keyboard) calls

    ps2_command(&atkbd->ps2dev, NULL, ATKBD_CMD_RESET_DEF);

which should turn off everything anyways.

But still, why ATKBD_CMD_RESET_DEF does not shut off the LEDs for you?

Looking at a ps/2 keyboard
document(http://www-ug.eecg.toronto.edu/msl/nios_devices/datasheets/PS2%20Keyboard%20Protocol.htm),
the F6 command does not seem to affect the state of the LED.

Thanks.

-- 
Dmitry

--
Qiang