Messages in this thread | | | Date | Mon, 25 Jan 2010 14:30:04 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH] Disable i8042 checks on Intel Apple Macs |
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On Mon, Jan 25, 2010 at 02:18:40PM -0800, H. Peter Anvin wrote: > On 01/25/2010 02:15 PM, Dmitry Torokhov wrote: > > On Mon, Jan 25, 2010 at 01:32:42PM -0800, H. Peter Anvin wrote: > >> On 01/25/2010 08:34 AM, Vojtech Pavlik wrote: > >>> > >>> Thus I believe that the right fix here is to figure out why the accesses > >>> to the ports 0x60/0x64 take a long time or forever on a Mac. Is it just > >>> that the kernel is timing out waiting for the i8042? Or is it something > >>> more sinister? > >>> > >> > >> In the A20 code in the setup code, I look for 0xFF coming back and > >> terminate the "wait for ready" loop much sooner than for other values. > >> 0xFF is a *possible* status value, but not a very *likely* one > >> (especially for repeated reads), as it would represent: > >> > >> parity error + receive timeout + transmit timeout + keyboard lock + > >> command + selftest OK + input full + output full. > >> > > > > You allow up to 32 0xFFs while i8042 driver does maximum 16 reads of > > whatever - if OBF is still raised we assume i8042 is not there. Does > > that mean that reads from 0x60 is what hurts on Macs? > > > > Bastien, could you try modifying drivers/input/serio/i8042.c:: > > i8042_flush() to not call i8042_read_data() when str is 0xff and see if > > it helps with lockups? > > > > We should never read from port 0x60 unless bit 1 in port 0x64 is set. > Do we do that?
No, we don't read of OBF is 0. Incidentially 0xff has it set ;) so we do try reading data port.
-- Dmitry
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