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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux ACPI <linux-acpi@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
 Hans de Goede <hdegoede@redhat.com>,
 Mario Limonciello <mario.limonciello@amd.com>, Armin Wolf <w_armin@gmx.de>,
 Heikki Krogerus <heikki.krogerus@linux.intel.com>
Subject:
 [PATCH v1 1/2] ACPI: EC: Install address space handler at the namespace root
Date: Fri, 10 May 2024 16:03:39 +0200
Message-ID: <4926735.31r3eYUQgx@kreacher>
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

It is reported that _DSM evaluation fails in ucsi_acpi_dsm() on Lenovo
IdeaPad Pro 5 due to a missing address space handler for the EC address
space:

 ACPI Error: No handler for Region [ECSI] (000000007b8176ee) [EmbeddedControl] (20230628/evregion-130)

This happens because the EC driver only registers the EC address space
handler for operation regions defined in the EC device scope of the
ACPI namespace while the operation region being accessed by the _DSM
in question is located beyond that scope.

To address this, modify the ACPI EC driver to install the EC address
space handler at the root of the ACPI namespace.

Note that this change is consistent with some examples in the ACPI
specification in which EC operation regions located outside the EC
device scope are used (for example, see Section 9.17.15 in ACPI 6.5),
so the current behavior of the EC driver is arguably questionable.

Reported-by: webcaptcha <webcapcha@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218789
Link: https://uefi.org/specs/ACPI/6.5/09_ACPI_Defined_Devices_and_Device_Specific_Objects.html#example-asl-code
Link: https://lore.kernel.org/linux-acpi/Zi+0whTvDbAdveHq@kuha.fi.intel.com
Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/ec.c       |   10 +++++-----
 drivers/acpi/internal.h |    1 -
 2 files changed, 5 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/acpi/ec.c
===================================================================
--- linux-pm.orig/drivers/acpi/ec.c
+++ linux-pm/drivers/acpi/ec.c
@@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct ac
 
 	if (!test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
 		acpi_ec_enter_noirq(ec);
-		status = acpi_install_address_space_handler_no_reg(ec->handle,
+		status = acpi_install_address_space_handler_no_reg(ACPI_ROOT_OBJECT,
 								   ACPI_ADR_SPACE_EC,
 								   &acpi_ec_space_handler,
 								   NULL, ec);
@@ -1497,11 +1497,10 @@ static int ec_install_handlers(struct ac
 			return -ENODEV;
 		}
 		set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
-		ec->address_space_handler_holder = ec->handle;
 	}
 
 	if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
-		acpi_execute_reg_methods(ec->handle, ACPI_ADR_SPACE_EC);
+		acpi_execute_reg_methods(ACPI_ROOT_OBJECT, ACPI_ADR_SPACE_EC);
 		set_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags);
 	}
 
@@ -1555,8 +1554,9 @@ static void ec_remove_handlers(struct ac
 {
 	if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
 		if (ACPI_FAILURE(acpi_remove_address_space_handler(
-					ec->address_space_handler_holder,
-					ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
+						ACPI_ROOT_OBJECT,
+						ACPI_ADR_SPACE_EC,
+						&acpi_ec_space_handler)))
 			pr_err("failed to remove space handler\n");
 		clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
 	}
Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -186,7 +186,6 @@ enum acpi_ec_event_state {
 
 struct acpi_ec {
 	acpi_handle handle;
-	acpi_handle address_space_handler_holder;
 	int gpe;
 	int irq;
 	unsigned long command_addr;