CVS commit: src/sys/dev/acpi

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Tue Jul 18 10:04:14 UTC 2023

Modified Files:
        src/sys/dev/acpi: acpi_ec.c

Log Message:
acpiec(4): Set sc_got_sci only when a transaction is over.

Before, when the acpiec thread noticed an SCI had been requested and
entered acpiec_gpe_state_machine to send the query command, it would
see the SCI is still requested -- because it had yet to acknowledge
it by setting the query command! -- and think the EC was asking for a
_second_ SCI.

So once the first SCI transaction was over, it would start a second
one, even though the EC hadn't asked for another -- and this would
wedge on some ECs.

Now, acpiec_gpe_state_machine waits to see what state we transition
to before taking the SCI bit to mean we need to notify the acpiec
thread to handle another query.

That way, when the acpiec thread enters acpiec_gpe_state_machine with
EC_STATE_QUERY, it can send the query command first, with the side
effect of clearing the SCI bit in subsequent reads of the status
register, and it won't think another SCI has been requested until it
returns to EC_STATE_FREE and sees the SCI bit set again in the status
register.

Possibly relevant PRs:

PR kern/53135
PR kern/52763
PR kern/57162


To generate a diff of this commit:
cvs rdiff -u -r1.91 -r1.92 src/sys/dev/acpi/acpi_ec.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.