Re: HPET force-enable investigations on Via VT8235

From: RafaÅ Bilski
Date: Tue Aug 07 2007 - 04:37:36 EST


RB> VT8235 does *NOT* have a HPET(*). Only part which has HPET is VT8237. It
RB> is device 00:17.0 too, but only 1106:3227 has HPET enable and memory
RB> base registers. VT8235 one and only feature which doesn't have driver
RB> yet seems to be hardware watchdog.
RB> (*) Datasheet revision 2.03 March 16, 2005

We have an Asrock K7VT4A+ board with VT8235 southbridge in our lab and it
does have an HPET. Just because the datasheet does not document HPET does
not mean it is not implemented.

My guess is that newer revisions of VT8235 have HPET whereas older revisions
do not. I'll get an lspci dump from our box tomorrow.
Indeed datasheet lies. I have VIA EPIA M10000 Rev. B motherboard.
% uname -r
2.6.23-rc1-hrt1

% dmesg | grep -i hpet
Force enabled HPET at base address 0xfed00000
hpet clockevent registered
hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0
hpet0: 3 32-bit timers, 14318180 Hz
Time: hpet clocksource has been installed.

% cat /proc/timer_list
[...]
Tick Device: mode: 1
Clock Event Device: hpet
max_delta_ns: 2147483647
min_delta_ns: 3352
mult: 61496110
shift: 32
mode: 3
next_event: 672664000000 nsecs
set_next_event: hpet_legacy_next_event
set_mode: hpet_legacy_set_mode
event_handler: hrtimer_interrupt

00:11.0 ISA bridge: VIA Technologies, Inc. VT8235 ISA Bridge
Subsystem: VIA Technologies, Inc. Unknown device aa01
Flags: bus master, stepping, medium devsel, latency 0
Capabilities: [c0] Power Management version 2
00: 06 11 77 31 87 00 10 02 00 00 01 06 00 00 80 00
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 06 11 01 aa
30: 00 00 00 00 c0 00 00 00 00 00 00 00 00 00 00 00
40: 45 00 f0 00 00 00 00 00 0c 20 00 00 44 00 0a 08
50: 81 1d 09 00 00 b0 a5 30 03 00 00 00 00 00 00 00
60: 00 00 00 00 00 00 00 04 80 00 d0 fe 00 00 00 00
70: 06 11 01 aa 00 00 00 00 00 00 00 00 20 00 00 00
80: 20 84 59 00 b2 30 00 00 01 04 00 00 00 18 00 00
90: 00 1f 50 88 b0 c0 00 00 00 97 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 01 05 01 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 14 88 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 16 00 00 00 00 00 01 00 00 00

Cheers,

- Udo
Regards
RafaÅ


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