Re: 2.6.3-bk7 i8042 does not work on a genuine i386 ibm ps/2 model 70.

[Vojtech Pavlik]

On Sun, Feb 29, 2004 at 07:32:19AM -0700, Eric W. Biederman wrote:
> 
> The i8042 driver attempts to detect if IBM PC compatiblity mode i.e.
> I8042_CTR_XLATE is enabled.  Unfortunately on a genuine IBM PS/2, (a pc
> incompatible :) this does not work. 
> 
> In i8042_controller_init if I disable the detection of the keyboard
> not being in XLATE mode everything works fine.
> 
> /*
>  * If the chip is configured into nontranslated mode by the BIOS, don't
>  * bother enabling translating and be happy.
>  */     
> #if 0
> 
> 	if (~i8042_ctr & I8042_CTR_XLATE)
> 		i8042_direct = 1;
> #endif
> 
> 
> The value of i8042_initial_ctr is 0x25 in case that helps.
> 
> I am not certain where to proceed from here.

This bit is an equivalent to 2.4 code in pc_keyb.c, that adds a
workaround for IBM PowerPC portables, which don't seem to support
translated mode:

       /* ibm powerpc portables need this to use scan-code set 1 -- Cort * */
        if (!(kbd_write_command_w_and_wait(KBD_CCMD_READ_MODE) & KBD_MODE_KCC))
        {
                /*
                 * If the controller does not support conversion,
                 * Set the keyboard to scan-code set 1.
                 */
                kbd_write_output_w(0xF0);
                kbd_wait_for_input();
                kbd_write_output_w(0x01);
                kbd_wait_for_input();
        }

As you can see, this sets the keyboard to scancode set 1, if
KBD_MODE_KCC (which is 0x40, same as I8042_CTR_XLATE), bit is set.

This should break your keyboard as well, if it supports mode setting.

I guess we could kill that bit, and ignore the old PowerPCs ....

> The piece I am certain about is that the keyboard controller has
> traditionally been a tiny microcontroller on PCs so that there is a
> wide variance in the commands and the exact format that they support.

Yes. The translate/don't bit is documented by IBM, though.

> And so far every data sheet I have looked at the documentation is
> slightly different.  The only real intel datasheet I could find was
> for the i8741A.  And it does not document the traditional interface
> implemented but the i8042, because that was done in firmware.
> 
> This machine is primarily a test machine to make certain my code
> works on older hardware.  So I am willing try any interesting or
> likely patches.

Does the machine by any chance have a PS/2 mouse port? If not, it may be
the reason - it would have an AT-style i8042, and those might not be
implementing that bit.

We could skip the above check if we don't detect the AUX port.

> My primary problem is that the code does not do the conservative
> thing and assume the BIOS setup the machine in PC compatible mode,
> and only when certain XLATE mode is implemented by the i8042 act on
> that information.  Instead the code is assumes it knows how the
> hardware works when in fact it does not.  
> 
> One solution might be check to assume XLATE mode is always enabled
> unless the underlying hardware matches a known list of superio chips.
> 
> It is extremely evil to try and use a machine when the scancodes are
> misinterpreted.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR
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