Re: [PATCH] s3_bios and lcall $0xc000,$3

[Nigel Cunningham <ncunningham-oKK1aGe2n869koe0gwxAeg@public.gmane.org>]

On Tue, 2003-02-18 at 14:42, Nigel Cunningham wrote:
> I'm talking about S3 (sorry typo before when I said S4==S5) - if I've
> read the specs right (and experience does match this), the i830 video
> card looses all state when switched to S3.

Sorry about replying to myself, but here are some extracts. I'm not at
all an expert on drivers, so I'll freely admit that I might be
misunderstanding these.

Page 1:
Intel® 830 Chipset Family: 82830
Graphics and Memory Controller
Hub (GMCH-M)
Datasheet
January 2002
Order Number: 298338-003

Page 180 says:
G1/S3: Power and context lost to chipset.

Page 184 adds...

The final level of power savings for the Intel 830 Chipset family GMCH-M
is achievable when the Host Clock, Memory Group, and I/O clock group
clocks are shutdown and the GMCH-M is powered down. This occurs when the
system transitions to the S3 state. During transition to the S3 state,
first the STPCLK# is asserted and the Stop Grant cycle snooped by the
GMCH-M and forwarded over Hub interface where it is received by the
ICH3-M. At this point the GMCH-M is functioning in the C2 State. The
GMCH-M places all of the SDRAM components into the self-refresh mode.
After the GMCH-M has placed all of the SDRAM components in self refresh,
it is safe to enter the STR State. The ICH3-M will then assert a signal,
SLP_S1#, to the clock synthesizer to shutdown all of the clocks in the
Host and Memory Clock Groups. The GMCH-M will assume that no AGP,
AGP/PCI, or hub interface cycle (except special cycles) will occur while
the GMCH-M is in the C3 State. The processor cannot snoop its caches to
maintain coherency while in the C3 State. GMCH-M contains no isolation
circuitry and MUST be powered down once STR is reached. If GMCHM is
powered up and driving outputs to devices that are powered down,
component damage will result.

(You may remember me talking a while ago about lspci -vv not even
looking sane after resume. I guess this is the cause).

Hope this is helpful.

Regards,

Nigel




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