Re: i8042 access timings

[Vojtech Pavlik <vojtech@suse.cz>]

On Thu, Jan 27, 2005 at 08:23:07AM +0200, Jaco Kroon wrote:
> Sebastian Piechocki wrote:
> >As I said I'm sending you mails from kernel masters:)
> Thanks.
> 
> >If you haven't such a problem, please send them your dmesg with 
> >i8042.debug and acpi=off.
> 
> I made an alternative plan.  I applied a custom patch that gives me far less
> output and prevents scrolling and gets what I hope is what is required.


... could you just increase the timeout value to some insane amount?
That should take care of the AUX_LOOP output getting back only after
issuing the next command.

Also, can you check if adding 'usb-handoff' to the kernel command line
helps you as well as it helped Sebastian?

> 
> 
> With acpi=on I get the following output:
> i8042_init()
> ACPI: PS/2 Keyboard Controller [KBC0] at I/O 0x60, 0x64, irq 1
> ACPI: PS/2 Mouse Controller [MSE0] at irq 12
> i8042_controller_init()
> i8042_flush()
> i8042_check_aux()
> i8042_flush()
> i8042_check_aux: param_in=0x5a, command=AUX_LOOP, param_out=5a <= -1
> i8042_check_aux: param_in=??, command=AUX_TEST, param_out=a5 <= 0
> i8042_allocate_kbd_port()
> i8042_port_register()
> 
> With acpi=off I get this:
> i8042_init()
> i8042: ACPI detection disabled
> i8042_controller_init()
> i8042_flush()
> i8042_check_aux()
> i8042_flush()
> i8042_check_aux:  passed
> i8042_check_mux()
> i8042_enable_mux_mode()
> i8042_flush()
> i8042_open(): mux_version==19
> i8042.c: Detected active multiplexing controller, rev 1.9.
> i8042_enable_mux_ports()
> i8042_allocate_mux_port()
> i8042_port_register()
> 
> Ok, some explanation is probably in order, I just put a printk(KERN_INFO 
> "function_name()\n" at the top of practically every function and then I 
> filled up i8042_check_aux() because that is where the error is detected. 
>  In the first case (the interesting one) these lines pop up:
> 
> i8042_check_aux: param_in=0x5a, command=AUX_LOOP, param_out=5a <= -1
> i8042_check_aux: param_in=??, command=AUX_TEST, param_out=a5 <= 0
> 
> Which indicates (as far as my understanding goes) that the command times 
> out, as such the param value stays the same (ready for re-use in the 
> second command).  The second commands succeeds but does not return one 
> of the expected (0x00, 0xff, 0xfa) values, instead it returns the value 
> as expected by the first command (0xa5).  The last value on both lines 
> is the return value.  From the second snippet:
> 
> i8042_flush()
> i8042_check_aux:  passed
> 
> Indicates that the outer test passed first time round, ie, exit code 0 
> and return param of 0xa5.  What I have done to get mine working with 
> acpi=on is applied the following patch (apologies if mozilla breaks this):
> 
> ======================
> --- linux-2.6.10/drivers/input/serio/i8042.c    2004-12-24 
> 23:33:52.000000000 +0200
> +++ linux-2.6.10-patched/drivers/input/serio/i8042.c    2005-01-24 
> 21:44:33.790291480 +0200
> @@ -595,7 +595,7 @@
>   */
> 
>                 if (i8042_command(&param, I8042_CMD_AUX_TEST)
> -                       || (param && param != 0xfa && param != 0xff))
> +                       || (param && param != 0xfa  && param != 0xa5 && 
> param != 0xff))
>                                 return -1;
>         }
> 
> ======================
> 
> Which I don't think is the proper solution, more likely the problem lies 
> in the i8042_command function.  Unfortunately I don't have time right 
> now to add more debug code (to possibly only issue those dbg statements 
> upto a certain point in order to reduce the amount of output).
> 
> > As I remember with acpi=off i8042 detects multplexer MUX with four ports!
> > I tried to make a hack for mux detection, but mux was detected and 
> touchpad
> > was not:(
> Yes.  This seems correct, however the touchoad worked "perfectly" for me 
> when I booted with acpi=off.
> 
> >Dmitry,
> > did you see this one?
> >
> >Since everything but the I8042_CMD_AUX_LOOP/AUX_TEST thing apparently
> >works, this is not the case of ACPI setting the wrong ports or something 
> >fundamental like that. It looks like some state of the keyboard controller 
> >just disables the loopback command and/or the AUX_TEST command.
> >
> >Might the "no KBD" case be something similar?
> I'm probably a bit off here, but what "no KBD" case?  On these 
> particular notebooks we both had to compile in specifically USB1.1 
> support in order to have keyboard support, but since I want USB support 
> in any case this is not a problem for me (although I would love to know 
> what caused this).
> 
> >Sebastian, can you make your hack also print out what the errors were (in 
> >particular, was it "i8042_command()" that failed, or was it that the 
> >return value was different from the expected ones, and if so - what?)
> I hope my debug did exactly that.
> 
> From the orriginal mail sent to me by Sebastian:
> >>In method:
> >> i8042_check_aux
> >>
> >>There is:
> >>param = 0x5a;
> >>       if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != 0xa5) 
> >>{
> >>
> >>/*
> >>* External connection test - filters out AT-soldered PS/2 i8042's
> >>* 0x00 - no error, 0x01-0x03 - clock/data stuck, 0xff - general error
> >>* 0xfa - no error on some notebooks which ignore the spec
> >>* Because it's common for chipsets to return error on perfectly 
> >>functioning
> >>* AUX ports, we test for this only when the LOOP command failed.
> >>*/
> >>
> >>               if (i8042_command(&param, I8042_CMD_AUX_TEST)
> >>                       || (param && param != 0xfa && param != 0xff))
> >>                               return -1;
> >>       }
> >>
> >>I have commented the line with return -1.
> >>I know that this solution is very stupid, but works fine.
> >>I use 2.6.11-rc1-mm1 kernel, and my touchpad is detected as ALPS.
> >>
> >>I think this is some special situation, that need extra detection 
> >>possibility? Am I right?
> Not sure yet.  It could be that the patch I've got covers all cases but 
> highly unlikely.
> 
> >>I can imagine a new chipset (I don't have the ATI IXP handy) that
> >>wouldn't care to implement the loopback and test commands on the AUX
> >>port. But what really surprises me here that disabling ACPI actually 
> >>helps.
> But I do.  So if you have any ideas I could try, or documentation to 
> point me at, now is the time.
> 
> >>Since Sebastian writes that the AUX check ends with a timeout, we also
> >>know that it never returns any datam so adding the printk() is probably
> >>pointless.
> From the above - isn't it simply that the timeout is too short? 
> Somehow enabling ACPI makes the timer go weird?  Will disabling HPET 
> make a difference?
> 
> >>Sebastian, here are a few shots in the dark: Does disabling Legacy USB
> >>emulation in the BIOS help? It might. Could you enable i8042.c DEBUG and
> >>compare the traces in the working and non-working cases side by side
> >>whether there is anything different prior to this failure point?
> 
> It doesn't look like there is any "legacy USB" options in the BIOS.  I 
> might just be missing it though :).
> 
> Right, long mail, sorry about that.
> 
> Jaco
> -- 
> There are only 10 kinds of people in this world,
>   those that understand binary and those that don't.
> http://www.kroon.co.za/
> 

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR