From: Lv Zheng <lv.zheng@intel.com>
Subject: [DBG PATCH] ACPI/EC: Add support to disallow QR_EC issued when SCI_EVT isn't set.

Currently we rely on the behaviour that the firmware can respond something
(for example, 0x00 to indicate "no outstanding events") to QR_EC even when
SCI_EVT is not set. But reporters has complained for AC/battery
pluging/unpluging, video brightness change delay caused on such platform
that the EC firmware refuse to respond QR_EC when SCI_EVT isn't set.

This is because the work queue that has issued QR_EC has to wait until
timeout in this case, and the _Qxx method evaluation queued after this work
item will be delayed.

By disallowing QR_EC issuing without completing the previous one, we are
able to handle this case.
Note that this patch can also fix CLEAR_ON_RESUME quirk which also relies
on this behavior.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611
Reported-by: Alexander Mezin <mezin.alexander@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
---
Index: linux-acpica/drivers/acpi/ec.c
===================================================================
--- linux-acpica.orig/drivers/acpi/ec.c
+++ linux-acpica/drivers/acpi/ec.c
@@ -186,6 +186,21 @@ static bool advance_transaction(struct a
 	t = ec->curr;
 	if (!t)
 		goto err;
+	/*
+	 * There is firmware refusing to respond QR_EC when SCI_EVT is not
+	 * set, for which case, we complete the QR_EC without issuing it to
+	 * the firmware.
+	 * https://bugzilla.kernel.org/show_bug.cgi?id=86211
+	 */
+	if (t->command == ACPI_EC_COMMAND_QUERY &&
+	    !(t->flags & ACPI_EC_COMMAND_POLL) &&
+	    !(status & ACPI_EC_FLAG_SCI)) {
+		pr_debug("gpe query is completed by software\n");
+		t->flags |= ACPI_EC_COMMAND_POLL;
+		t->rdata[t->ri++] = 0x00;
+		t->flags |= ACPI_EC_COMMAND_COMPLETE;
+		wakeup = true;
+	}
 	if (t->flags & ACPI_EC_COMMAND_POLL) {
 		if (t->wlen > t->wi) {
 			if ((status & ACPI_EC_FLAG_IBF) == 0)
@@ -196,6 +211,8 @@ static bool advance_transaction(struct a
 			if ((status & ACPI_EC_FLAG_OBF) == 1) {
 				t->rdata[t->ri++] = acpi_ec_read_data(ec);
 				if (t->rlen == t->ri) {
+					if (t->command == ACPI_EC_COMMAND_QUERY)
+						pr_debug("gpe query is completed by hardware\n");
 					t->flags |= ACPI_EC_COMMAND_COMPLETE;
 					wakeup = true;
 				}