ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.
authorLv Zheng <lv.zheng@intel.com>
Thu, 11 Jun 2015 05:21:45 +0000 (13:21 +0800)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Mon, 15 Jun 2015 12:35:59 +0000 (14:35 +0200)
commit3cb02aeb28dd3f1b8a132fa3ecf6db17afd518d6
treeb100aae5ed5cbbc6b1f0b32a9c9139eeb25bbe38
parent1d68d2612c2e7309166fa43d8e27eb163435527f
ACPI / EC: Fix EC_FLAGS_QUERY_HANDSHAKE platforms using new event clearing timing.

It is reported that on several platforms, EC firmware will not respond
non-expected QR_EC (see EC_FLAGS_QUERY_HANDSHAKE, only write QR_EC when
SCI_EVT is set).

Unfortunately, ACPI specification doesn't define when the SCI_EVT should be
cleared by the firmware, thus the original implementation queued up second
QR_EC right after writing QR_EC command and before reading the returned
event value as at that time the SCI_EVT is ensured not cleared. This
behavior is also based on the assumption that the firmware should be able
to return 0x00 to indicate "no outstanding event". This behavior did fix
issues on Samsung platforms where the spurious query value of 0x00 is
supported and didn't break platforms in my test queue.

But recently, specific Acer, Asus, Lenovo platforms keep on blaming this
change.

This patch changes the behavior to re-check the SCI_EVT a bit later and
removes EC_FLAGS_QUERY_HANDSHAKE quirks, hoping this is the Windows
compliant EC driver behavior.

In order to be robust to the possible regressions, instead of removing the
quirk directly, this patch keeps the quirk code, removes the quirk users
and keeps old behavior for Samsung platforms.

Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94411
Link: https://bugzilla.kernel.org/show_bug.cgi?id=97381
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98111
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-and-tested-by: Tigran Gabrielyan <tigrangab@gmail.com>
Reported-and-tested-by: Adrien D <ghbdtn@openmailbox.org>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
drivers/acpi/ec.c