diff mbox series

[v2,1/2] ACPI: EC: Install address space handler at the namespace root

Message ID 6046110.lOV4Wx5bFT@kreacher (mailing list archive)
State Mainlined, archived
Headers show
Series ACPI: EC: Install EC address space handler at the namespace root | expand

Commit Message

Rafael J. Wysocki May 15, 2024, 7:40 p.m. UTC 
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 if there is no ECDT, 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 for the first EC that
can be found regardless of whether or not an ECDT is present.

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>
---

v1 -> v2:
   * Update the changelog to correctly cover the driver behavior
     when ECDT is present
   * Install the address space handler at the namespace root for
     first_ec only
   * Set first_ec before calling ec_install_handlers() in
     acpi_ec_setup() (Hans)

---
 drivers/acpi/ec.c       |   25 ++++++++++++++++---------
 drivers/acpi/internal.h |    1 -
 2 files changed, 16 insertions(+), 10 deletions(-)

Comments

Andy Shevchenko May 16, 2024, 10:22 a.m. UTC | #1 
On Wed, May 15, 2024 at 09:40:54PM +0200, Rafael J. Wysocki wrote:
> 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 if there is no ECDT, 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 for the first EC that
> can be found regardless of whether or not an ECDT is present.
> 
> 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.

...

> -		status = acpi_install_address_space_handler_no_reg(ec->handle,
> +		status = acpi_install_address_space_handler_no_reg(scope_handle,
>  								   ACPI_ADR_SPACE_EC,
>  								   &acpi_ec_space_handler,
>  								   NULL, ec);

Looking at this...

>  		if (ACPI_FAILURE(acpi_remove_address_space_handler(
> +						scope_handle,
> +						ACPI_ADR_SPACE_EC,
> +						&acpi_ec_space_handler)))

...and this, I believe you can move scope_handle to the previous line and align
the rest for the sake of consistency and slightly better readability.
Rafael J. Wysocki May 16, 2024, 10:26 a.m. UTC | #2 
On Thu, May 16, 2024 at 12:22 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, May 15, 2024 at 09:40:54PM +0200, Rafael J. Wysocki wrote:
> > 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 if there is no ECDT, 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 for the first EC that
> > can be found regardless of whether or not an ECDT is present.
> >
> > 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.
>
> ...
>
> > -             status = acpi_install_address_space_handler_no_reg(ec->handle,
> > +             status = acpi_install_address_space_handler_no_reg(scope_handle,
> >                                                                  ACPI_ADR_SPACE_EC,
> >                                                                  &acpi_ec_space_handler,
> >                                                                  NULL, ec);
>
> Looking at this...
>
> >               if (ACPI_FAILURE(acpi_remove_address_space_handler(
> > +                                             scope_handle,
> > +                                             ACPI_ADR_SPACE_EC,
> > +                                             &acpi_ec_space_handler)))
>
> ...and this, I believe you can move scope_handle to the previous line and align
> the rest for the sake of consistency and slightly better readability.

Well, I prefer to cut a separate cleanup patch to make this more consistent.
diff mbox series

Patch

Index: linux-pm/drivers/acpi/ec.c
===================================================================
--- linux-pm.orig/drivers/acpi/ec.c
+++ linux-pm/drivers/acpi/ec.c
@@ -1482,13 +1482,14 @@  static bool install_gpio_irq_event_handl
 static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
 			       bool call_reg)
 {
+	acpi_handle scope_handle = ec == first_ec ? ACPI_ROOT_OBJECT : ec->handle;
 	acpi_status status;
 
 	acpi_ec_start(ec, false);
 
 	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(scope_handle,
 								   ACPI_ADR_SPACE_EC,
 								   &acpi_ec_space_handler,
 								   NULL, ec);
@@ -1497,11 +1498,10 @@  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(scope_handle, ACPI_ADR_SPACE_EC);
 		set_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags);
 	}
 
@@ -1553,10 +1553,13 @@  static int ec_install_handlers(struct ac
 
 static void ec_remove_handlers(struct acpi_ec *ec)
 {
+	acpi_handle scope_handle = ec == first_ec ? ACPI_ROOT_OBJECT : ec->handle;
+
 	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)))
+						scope_handle,
+						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);
 	}
@@ -1595,14 +1598,18 @@  static int acpi_ec_setup(struct acpi_ec
 {
 	int ret;
 
-	ret = ec_install_handlers(ec, device, call_reg);
-	if (ret)
-		return ret;
-
 	/* First EC capable of handling transactions */
 	if (!first_ec)
 		first_ec = ec;
 
+	ret = ec_install_handlers(ec, device, call_reg);
+	if (ret) {
+		if (ec == first_ec)
+			first_ec = NULL;
+
+		return ret;
+	}
+
 	pr_info("EC_CMD/EC_SC=0x%lx, EC_DATA=0x%lx\n", ec->command_addr,
 		ec->data_addr);
 
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;