lkml.org 
[lkml]   [2018]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [RFC PATCH v2 09/14] m68k: hp300: Remove hp300_gettimeoffset()
Hi Finn,

On Wed, Nov 21, 2018 at 12:13 AM Finn Thain <fthain@telegraphics.com.au> wrote:
> On atari, the 68901 counts down to 0x01 and raises an interrupt. On mac,
> the 6522 counts down to 0xFFFF then raises an interrupt. No idea about
> amiga (Geert?) -- this has to be handled correctly to get a monotonic
> clocksource. I'll fix this in v3 (where the information is available).

The docs state that the CIA generates on interrupt on underflow, so I
guess that's the same behavior as the 6522 VIA.

Unfortunately the 24-bit ("TOD") counters in the two CIAs run from HSYNC
resp. VSYNC, which depends on the video mode, and thus can't be used
as a monotonic clock source.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

\
 
 \ /
  Last update: 2018-11-21 09:12    [W:0.072 / U:1.984 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site