The patch below does not apply to the 3.17-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From df9ff91801da603079018f21a9412385b62f0f8e Mon Sep 17 00:00:00 2001
From: Lv Zheng <lv.zheng@xxxxxxxxx>
Date: Wed, 29 Oct 2014 11:33:43 +0800
Subject: [PATCH] Revert "ACPI / EC: Add support to disallow QR_EC to be issued
before completing previous QR_EC"
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
It is reported that the following commit breaks Samsung hardware:
Commit: 558e4736f2e1b0e6323adf7a5e4df77ed6cfc1a4.
Subject: ACPI / EC: Add support to disallow QR_EC to be issued before
completing previous QR_EC
Which means the Samsung behavior conflicts with the Acer behavior.
1. Samsung may behave like:
[ +event 1 ] SCI_EVT set
[ +event 2 ] SCI_EVT set
write QR_EC
read event
[ -event 1 ] SCI_EVT clear
Without the above commit, Samsung can work:
[ +event 1 ] SCI_EVT set
[ +event 2 ] SCI_EVT set
write QR_EC
CAN prepare next QR_EC as SCI_EVT=1
read event
[ -event 1 ] SCI_EVT clear
write QR_EC
read event
[ -event 2 ] SCI_EVT clear
With the above commit, Samsung cannot work:
[ +event 1 ] SCI_EVT set
[ +event 2 ] SCI_EVT set
write QR_EC
read event
[ -event 1 ] SCI_EVT clear
CANNOT prepare next QR_EC as SCI_EVT=0
2. Acer may behave like:
[ +event 1 ] SCI_EVT set
[ +event 2 ]
write QR_EC
read event
[ -event 1 ] SCI_EVT clear
[ +event 2 ] SCI_EVT set
Without the above commit, Acer cannot work when there is only 1 event:
[ +event 1 ] SCI_EVT set
write QR_EC
can prepared next QR_EC as SCI_EVT=1
read event
[ -event 1 ] SCI_EVT clear
CANNOT write QR_EC as SCI_EVT=0
With the above commit, Acer can work:
[ +event 1 ] SCI_EVT set
[ +event 2 ]
write QR_EC
read event
[ -event 1 ] SCI_EVT set
can prepare next QR_EC because SCI_EVT=0
CAN write QR_EC as SCI_EVT=1
Since Acer can also work with only the following commit applied:
Commit: 3afcf2ece453e1a8c2c6de19cdf06da3772a1b08
Subject: ACPI / EC: Add support to disallow QR_EC to be issued when
SCI_EVT isn't set
commit 558e4736f2e1b0e6323adf7a5e4df77ed6cfc1a4 can be reverted.
Fixes: 558e4736f2e1 (ACPI / EC: Add support to disallow QR_EC to be issued ...)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161
Reported-and-tested-by: Ortwin Glück <odi@xxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
Cc: 3.17+ <stable@xxxxxxxxxxxxxxx> # 3.17+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 3d304ff7f095..31b699f2d088 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -334,13 +334,13 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
pr_debug("***** Command(%s) started *****\n",
acpi_ec_cmd_string(t->command));
start_transaction(ec);
- spin_unlock_irqrestore(&ec->lock, tmp);
- ret = ec_poll(ec);
- spin_lock_irqsave(&ec->lock, tmp);
if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
pr_debug("***** Event stopped *****\n");
}
+ spin_unlock_irqrestore(&ec->lock, tmp);
+ ret = ec_poll(ec);
+ spin_lock_irqsave(&ec->lock, tmp);
pr_debug("***** Command(%s) stopped *****\n",
acpi_ec_cmd_string(t->command));
ec->curr = NULL;
--
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