Re: PS/2 + i8042 intermixing commands

On Thu, Aug 06, 2020 at 09:28:41AM -0600, Raul Rangel wrote:

quoted

<- atkbd_event_work->atkbd_set_leds
[KB recv data: 0xed] # CMD 10
<- Wait, where is the data?

<- Continuation of i8042_port_close?
[KB recv cmd: 0x60] # CMD #14
[KB recv data: 0x43]
[KB eaten by STATE_WRITE_CMD_BYTE: 0x43]
[KB set CTR_RAM(0x00)=0x43 (old:0x41)]
[AUX IRQ enable]

<- Here is the data!
[KB recv data: 0x00] # CMD 10 (data)
[KB Unsupported i8042 data 0x00]
[KB recv data: 0x00] <- Did the host retry?
[KB Unsupported i8042 data 0x00]

<- atkbd_event_work->atkbd_set_repeat_rate
[KB recv data: 0xf3] # CMD #11
[KB recv data: 0x00]
[KB eaten by STATE_SETREP: 0x00]

[KB recv cmd: 0xd4] # CMD #15
[KB recv data: 0xf2]
[STATE_SEND_TO_MOUSE: 0xf2]

As you can see CMD #10 starts between #13 and #14, and then completes
after #14. Is this expected behavior?

I'm not quite sure if #13 and #14 are coming from i8042_port_close. I
don't have a function trace available, but it seems to fit.

I found this comment:
/*
 * Writers to AUX and KBD ports as well as users issuing i8042_command
 * directly should acquire i8042_mutex (by means of calling
 * i8042_lock_chip() and i8042_unlock_ship() helpers) to ensure that
 * they do not disturb each other (unfortunately in many i8042
 * implementations write to one of the ports will immediately abort
 * command that is being processed by another port).
 */
static DEFINE_MUTEX(i8042_mutex);

Does that not mean that i8042_port_close, i8042_enable_kbd_port,
i8042_enable_aux_port, + any other function that calls i8042_command
should be taking the lock before calling i8042_command?

Yeah, I think this is right. When I added the mutex it was because 2
deices were clashing with each other and I did not consider that closing
port in the i8042 driver itself may also disturb in-flight command.

Thanks.

-- 
Dmitry