Missing default handler for the EmbeddedControl OpRegion

Missing default handler for the EmbeddedControl OpRegion

[Heikki Krogerus]

Hi,

There's a bug that is caused by an EmbeddedControl OpRegion which is
declared inside the scope of a specific USB Type-C device (PNP0CA0):
https://bugzilla.kernel.org/show_bug.cgi?id=218789

It looks like that's not the only case where that OpRegion ID is used
outside of the EC device scope. There is at least one driver in Linux
Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
for the EmbeddedControl OpRegion, and based on a quick search, the
problem "Region EmbeddedControl (ID=3) has no handler" has happened
with some other devices too.


Br,

-- 
heikki

Re: Missing default handler for the EmbeddedControl OpRegion

[Armin Wolf]

Am 29.04.24 um 16:54 schrieb Heikki Krogerus:

> Hi,
>
> There's a bug that is caused by an EmbeddedControl OpRegion which is
> declared inside the scope of a specific USB Type-C device (PNP0CA0):
> https://bugzilla.kernel.org/show_bug.cgi?id=218789
>
> It looks like that's not the only case where that OpRegion ID is used
> outside of the EC device scope. There is at least one driver in Linux
> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> for the EmbeddedControl OpRegion, and based on a quick search, the
> problem "Region EmbeddedControl (ID=3) has no handler" has happened
> with some other devices too.
>
>
> Br,
>
Hi,

i support your proposal, but i think we first have to figure out how Windows
handles such cases. Those devices are build for and tested with Windows only,
so Windows seems to specify some behavior which allows for this.

I will try to contact Microsoft and ask them how the Windows Kernel handles
this OpRegions.

Thanks,
Armin Wolf

Re: Missing default handler for the EmbeddedControl OpRegion

[Rafael J. Wysocki]

Hi,

On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
<heikki.krogerus@linux.intel.com> wrote:
>
> Hi,
>
> There's a bug that is caused by an EmbeddedControl OpRegion which is
> declared inside the scope of a specific USB Type-C device (PNP0CA0):
> https://bugzilla.kernel.org/show_bug.cgi?id=218789

And in this bug you are essentially proposing to install the EC
OpRegion handler at the namespace root instead of the EC device.

This sounds reasonable, although AFAICS this is a matter of modifying
the EC driver (before the EC OpRegion handler is installed by the EC
drvier, ACPICA has no way to handle EC address space accesses anyway).

> It looks like that's not the only case where that OpRegion ID is used
> outside of the EC device scope. There is at least one driver in Linux
> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> for the EmbeddedControl OpRegion, and based on a quick search, the
> problem "Region EmbeddedControl (ID=3) has no handler" has happened
> with some other devices too.

AFAICS, installing the EC address space handler at the EC device
object itself is not based on any sound technical arguments, it's just
been always done this way in Linux.  It's quite possible that the EC
address space handler should have been installed at the namespace root
from the outset.

Thanks!

Re: Missing default handler for the EmbeddedControl OpRegion

[Heikki Krogerus]

On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
> Hi,
> 
> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
> <heikki.krogerus@linux.intel.com> wrote:
> >
> > Hi,
> >
> > There's a bug that is caused by an EmbeddedControl OpRegion which is
> > declared inside the scope of a specific USB Type-C device (PNP0CA0):
> > https://bugzilla.kernel.org/show_bug.cgi?id=218789
> 
> And in this bug you are essentially proposing to install the EC
> OpRegion handler at the namespace root instead of the EC device.
> 
> This sounds reasonable, although AFAICS this is a matter of modifying
> the EC driver (before the EC OpRegion handler is installed by the EC
> drvier, ACPICA has no way to handle EC address space accesses anyway).
> 
> > It looks like that's not the only case where that OpRegion ID is used
> > outside of the EC device scope. There is at least one driver in Linux
> > Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> > for the EmbeddedControl OpRegion, and based on a quick search, the
> > problem "Region EmbeddedControl (ID=3) has no handler" has happened
> > with some other devices too.
> 
> AFAICS, installing the EC address space handler at the EC device
> object itself is not based on any sound technical arguments, it's just
> been always done this way in Linux.  It's quite possible that the EC
> address space handler should have been installed at the namespace root
> from the outset.

Okay, thank you for the explanation. So can we simply change it like
this (I may have still misunderstood something)?

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 02255795b800..6b9dd27171ee 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
 
        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);
@@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
                        return -ENODEV;
                }
                set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
-               ec->address_space_handler_holder = ec->handle;
+               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
        }
 
        if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {

thanks,

-- 
heikki

Re: Missing default handler for the EmbeddedControl OpRegion

[Rafael J. Wysocki]

On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
> > Hi,
> > 
> > On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
> > <heikki.krogerus@linux.intel.com> wrote:
> > >
> > > Hi,
> > >
> > > There's a bug that is caused by an EmbeddedControl OpRegion which is
> > > declared inside the scope of a specific USB Type-C device (PNP0CA0):
> > > https://bugzilla.kernel.org/show_bug.cgi?id=218789
> > 
> > And in this bug you are essentially proposing to install the EC
> > OpRegion handler at the namespace root instead of the EC device.
> > 
> > This sounds reasonable, although AFAICS this is a matter of modifying
> > the EC driver (before the EC OpRegion handler is installed by the EC
> > drvier, ACPICA has no way to handle EC address space accesses anyway).
> > 
> > > It looks like that's not the only case where that OpRegion ID is used
> > > outside of the EC device scope. There is at least one driver in Linux
> > > Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> > > for the EmbeddedControl OpRegion, and based on a quick search, the
> > > problem "Region EmbeddedControl (ID=3) has no handler" has happened
> > > with some other devices too.
> > 
> > AFAICS, installing the EC address space handler at the EC device
> > object itself is not based on any sound technical arguments, it's just
> > been always done this way in Linux.  It's quite possible that the EC
> > address space handler should have been installed at the namespace root
> > from the outset.
> 
> Okay, thank you for the explanation. So can we simply change it like
> this (I may have still misunderstood something)?

Roughly speaking, yes, but it is missing an analogous change around
the removal.

Please see the appended patch (which I have created independently in
the meantime).  It doesn't break stuff for me and Andy points out that
there are examples of EmbeddedControl OpRegions outside the EC device
scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).

So I think that this change can be made relatively safely (but adding Hans and
Mario to the CC in case they know something that might be broken by it).


> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
> index 02255795b800..6b9dd27171ee 100644
> --- a/drivers/acpi/ec.c
> +++ b/drivers/acpi/ec.c
> @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>  
>         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);
> @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>                         return -ENODEV;
>                 }
>                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
> -               ec->address_space_handler_holder = ec->handle;
> +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
>         }
>  
>         if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
> 

---
 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;

Re: Missing default handler for the EmbeddedControl OpRegion

[Rafael J. Wysocki]

[Resending because it appears to have got lost, sorry for duplicates.]

On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
> > Hi,
> > 
> > On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
> > <heikki.krogerus@linux.intel.com> wrote:
> > >
> > > Hi,
> > >
> > > There's a bug that is caused by an EmbeddedControl OpRegion which is
> > > declared inside the scope of a specific USB Type-C device (PNP0CA0):
> > > https://bugzilla.kernel.org/show_bug.cgi?id=218789
> > 
> > And in this bug you are essentially proposing to install the EC
> > OpRegion handler at the namespace root instead of the EC device.
> > 
> > This sounds reasonable, although AFAICS this is a matter of modifying
> > the EC driver (before the EC OpRegion handler is installed by the EC
> > drvier, ACPICA has no way to handle EC address space accesses anyway).
> > 
> > > It looks like that's not the only case where that OpRegion ID is used
> > > outside of the EC device scope. There is at least one driver in Linux
> > > Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> > > for the EmbeddedControl OpRegion, and based on a quick search, the
> > > problem "Region EmbeddedControl (ID=3) has no handler" has happened
> > > with some other devices too.
> > 
> > AFAICS, installing the EC address space handler at the EC device
> > object itself is not based on any sound technical arguments, it's just
> > been always done this way in Linux.  It's quite possible that the EC
> > address space handler should have been installed at the namespace root
> > from the outset.
> 
> Okay, thank you for the explanation. So can we simply change it like
> this (I may have still misunderstood something)?

Roughly speaking, yes, but it is missing an analogous change around
the removal.

Please see the appended patch (which I have created independently in
the meantime).  It doesn't break stuff for me and Andy points out that
there are examples of EmbeddedControl OpRegions outside the EC device
scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).

So I think that this change can be made relatively safely (but adding Hans and
Mario to the CC in case they know something that might be broken by it).


> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
> index 02255795b800..6b9dd27171ee 100644
> --- a/drivers/acpi/ec.c
> +++ b/drivers/acpi/ec.c
> @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>  
>         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);
> @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>                         return -ENODEV;
>                 }
>                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
> -               ec->address_space_handler_holder = ec->handle;
> +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
>         }
>  
>         if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
> 

---
 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;

Re: Missing default handler for the EmbeddedControl OpRegion

[Rafael J. Wysocki]

On Wed, May 8, 2024 at 2:50 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> [Resending because it appears to have got lost, sorry for duplicates.]
>
> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
> > On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
> > > Hi,
> > >
> > > On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
> > > <heikki.krogerus@linux.intel.com> wrote:
> > > >
> > > > Hi,
> > > >
> > > > There's a bug that is caused by an EmbeddedControl OpRegion which is
> > > > declared inside the scope of a specific USB Type-C device (PNP0CA0):
> > > > https://bugzilla.kernel.org/show_bug.cgi?id=218789
> > >
> > > And in this bug you are essentially proposing to install the EC
> > > OpRegion handler at the namespace root instead of the EC device.
> > >
> > > This sounds reasonable, although AFAICS this is a matter of modifying
> > > the EC driver (before the EC OpRegion handler is installed by the EC
> > > drvier, ACPICA has no way to handle EC address space accesses anyway).
> > >
> > > > It looks like that's not the only case where that OpRegion ID is used
> > > > outside of the EC device scope. There is at least one driver in Linux
> > > > Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> > > > for the EmbeddedControl OpRegion, and based on a quick search, the
> > > > problem "Region EmbeddedControl (ID=3) has no handler" has happened
> > > > with some other devices too.
> > >
> > > AFAICS, installing the EC address space handler at the EC device
> > > object itself is not based on any sound technical arguments, it's just
> > > been always done this way in Linux.  It's quite possible that the EC
> > > address space handler should have been installed at the namespace root
> > > from the outset.
> >
> > Okay, thank you for the explanation. So can we simply change it like
> > this (I may have still misunderstood something)?
>
> Roughly speaking, yes, but it is missing an analogous change around
> the removal.

Actually, not around the removal, but around the evaluation of _REG
methods and dropping address_space_handler_holder is better IMO,
because it will always be ACPI_ROOT_OBJECT now.

> Please see the appended patch (which I have created independently in
> the meantime).  It doesn't break stuff for me and Andy points out that
> there are examples of EmbeddedControl OpRegions outside the EC device
> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
>
> So I think that this change can be made relatively safely (but adding Hans and
> Mario to the CC in case they know something that might be broken by it).
>
>
> > diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
> > index 02255795b800..6b9dd27171ee 100644
> > --- a/drivers/acpi/ec.c
> > +++ b/drivers/acpi/ec.c
> > @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
> >
> >         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);
> > @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
> >                         return -ENODEV;
> >                 }
> >                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
> > -               ec->address_space_handler_holder = ec->handle;
> > +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
> >         }
> >
> >         if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
> >
>
> ---
>  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;
>
>
>

Re: Missing default handler for the EmbeddedControl OpRegion

[Mario Limonciello]

On 5/8/2024 07:50, Rafael J. Wysocki wrote:
> [Resending because it appears to have got lost, sorry for duplicates.]
> 
> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
>> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
>>> Hi,
>>>
>>> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
>>> <heikki.krogerus@linux.intel.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> There's a bug that is caused by an EmbeddedControl OpRegion which is
>>>> declared inside the scope of a specific USB Type-C device (PNP0CA0):
>>>> https://bugzilla.kernel.org/show_bug.cgi?id=218789
>>>
>>> And in this bug you are essentially proposing to install the EC
>>> OpRegion handler at the namespace root instead of the EC device.
>>>
>>> This sounds reasonable, although AFAICS this is a matter of modifying
>>> the EC driver (before the EC OpRegion handler is installed by the EC
>>> drvier, ACPICA has no way to handle EC address space accesses anyway).
>>>
>>>> It looks like that's not the only case where that OpRegion ID is used
>>>> outside of the EC device scope. There is at least one driver in Linux
>>>> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
>>>> for the EmbeddedControl OpRegion, and based on a quick search, the
>>>> problem "Region EmbeddedControl (ID=3) has no handler" has happened
>>>> with some other devices too.
>>>
>>> AFAICS, installing the EC address space handler at the EC device
>>> object itself is not based on any sound technical arguments, it's just
>>> been always done this way in Linux.  It's quite possible that the EC
>>> address space handler should have been installed at the namespace root
>>> from the outset.
>>
>> Okay, thank you for the explanation. So can we simply change it like
>> this (I may have still misunderstood something)?
> 
> Roughly speaking, yes, but it is missing an analogous change around
> the removal.
> 
> Please see the appended patch (which I have created independently in
> the meantime).  It doesn't break stuff for me and Andy points out that
> there are examples of EmbeddedControl OpRegions outside the EC device
> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
> 
> So I think that this change can be made relatively safely (but adding Hans and
> Mario to the CC in case they know something that might be broken by it).

Nothing jumps out at me, it looks like a good way to handle this issue.

> 
> 
>> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
>> index 02255795b800..6b9dd27171ee 100644
>> --- a/drivers/acpi/ec.c
>> +++ b/drivers/acpi/ec.c
>> @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>   
>>          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);
>> @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>                          return -ENODEV;
>>                  }
>>                  set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
>> -               ec->address_space_handler_holder = ec->handle;
>> +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
>>          }
>>   
>>          if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
>>
> 
> ---
>   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;
> 
> 

Re: Missing default handler for the EmbeddedControl OpRegion

[Hans de Goede]

Hi Rafael,

On 5/8/24 2:50 PM, Rafael J. Wysocki wrote:
> [Resending because it appears to have got lost, sorry for duplicates.]
> 
> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
>> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
>>> Hi,
>>>
>>> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
>>> <heikki.krogerus@linux.intel.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> There's a bug that is caused by an EmbeddedControl OpRegion which is
>>>> declared inside the scope of a specific USB Type-C device (PNP0CA0):
>>>> https://bugzilla.kernel.org/show_bug.cgi?id=218789
>>>
>>> And in this bug you are essentially proposing to install the EC
>>> OpRegion handler at the namespace root instead of the EC device.
>>>
>>> This sounds reasonable, although AFAICS this is a matter of modifying
>>> the EC driver (before the EC OpRegion handler is installed by the EC
>>> drvier, ACPICA has no way to handle EC address space accesses anyway).
>>>
>>>> It looks like that's not the only case where that OpRegion ID is used
>>>> outside of the EC device scope. There is at least one driver in Linux
>>>> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
>>>> for the EmbeddedControl OpRegion, and based on a quick search, the
>>>> problem "Region EmbeddedControl (ID=3) has no handler" has happened
>>>> with some other devices too.
>>>
>>> AFAICS, installing the EC address space handler at the EC device
>>> object itself is not based on any sound technical arguments, it's just
>>> been always done this way in Linux.  It's quite possible that the EC
>>> address space handler should have been installed at the namespace root
>>> from the outset.
>>
>> Okay, thank you for the explanation. So can we simply change it like
>> this (I may have still misunderstood something)?
> 
> Roughly speaking, yes, but it is missing an analogous change around
> the removal.
> 
> Please see the appended patch (which I have created independently in
> the meantime).  It doesn't break stuff for me and Andy points out that
> there are examples of EmbeddedControl OpRegions outside the EC device
> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
> 
> So I think that this change can be made relatively safely (but adding Hans and
> Mario to the CC in case they know something that might be broken by it).

+Cc Armin for WMI EC handler 

No objections from me against registering the EC handler at the root,
when I saw that the WMI driver was registering its own handler I was
already wondering why we did not just register the acpi/ec.c handler at
the root level but I did not have time to pursue this further.

One question which I have is does the drivers/acpi/ec.c version handle
read/writes of a width other then 8 bits ? Armin recently added support
for other widths to the WMI version of the OpRegion handler to fix
issues on some laptop models:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c663b26972eae7d2a614f584c92a266fe9a2d44c

Regards,

Hans



>> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
>> index 02255795b800..6b9dd27171ee 100644
>> --- a/drivers/acpi/ec.c
>> +++ b/drivers/acpi/ec.c
>> @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>  
>>         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);
>> @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>                         return -ENODEV;
>>                 }
>>                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
>> -               ec->address_space_handler_holder = ec->handle;
>> +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
>>         }
>>  
>>         if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
>>
> 
> ---
>  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;
> 
> 

Re: Missing default handler for the EmbeddedControl OpRegion

[Armin Wolf]

Am 09.05.24 um 12:35 schrieb Hans de Goede:

> Hi Rafael,
>
> On 5/8/24 2:50 PM, Rafael J. Wysocki wrote:
>> [Resending because it appears to have got lost, sorry for duplicates.]
>>
>> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
>>> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
>>>> Hi,
>>>>
>>>> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
>>>> <heikki.krogerus@linux.intel.com> wrote:
>>>>> Hi,
>>>>>
>>>>> There's a bug that is caused by an EmbeddedControl OpRegion which is
>>>>> declared inside the scope of a specific USB Type-C device (PNP0CA0):
>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=218789
>>>> And in this bug you are essentially proposing to install the EC
>>>> OpRegion handler at the namespace root instead of the EC device.
>>>>
>>>> This sounds reasonable, although AFAICS this is a matter of modifying
>>>> the EC driver (before the EC OpRegion handler is installed by the EC
>>>> drvier, ACPICA has no way to handle EC address space accesses anyway).
>>>>
>>>>> It looks like that's not the only case where that OpRegion ID is used
>>>>> outside of the EC device scope. There is at least one driver in Linux
>>>>> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
>>>>> for the EmbeddedControl OpRegion, and based on a quick search, the
>>>>> problem "Region EmbeddedControl (ID=3) has no handler" has happened
>>>>> with some other devices too.
>>>> AFAICS, installing the EC address space handler at the EC device
>>>> object itself is not based on any sound technical arguments, it's just
>>>> been always done this way in Linux.  It's quite possible that the EC
>>>> address space handler should have been installed at the namespace root
>>>> from the outset.
>>> Okay, thank you for the explanation. So can we simply change it like
>>> this (I may have still misunderstood something)?
>> Roughly speaking, yes, but it is missing an analogous change around
>> the removal.
>>
>> Please see the appended patch (which I have created independently in
>> the meantime).  It doesn't break stuff for me and Andy points out that
>> there are examples of EmbeddedControl OpRegions outside the EC device
>> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
>>
>> So I think that this change can be made relatively safely (but adding Hans and
>> Mario to the CC in case they know something that might be broken by it).
> +Cc Armin for WMI EC handler
>
> No objections from me against registering the EC handler at the root,
> when I saw that the WMI driver was registering its own handler I was
> already wondering why we did not just register the acpi/ec.c handler at
> the root level but I did not have time to pursue this further.
>
> One question which I have is does the drivers/acpi/ec.c version handle
> read/writes of a width other then 8 bits ? Armin recently added support
> for other widths to the WMI version of the OpRegion handler to fix
> issues on some laptop models:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c663b26972eae7d2a614f584c92a266fe9a2d44c
>
> Regards,
>
> Hans

Hi,

the handling of multi-byte reads/writes was taken from the ec driver itself, so
using the standard ec handler should make no difference for the WMI driver.

Thanks,
Armin Wolf

>>> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
>>> index 02255795b800..6b9dd27171ee 100644
>>> --- a/drivers/acpi/ec.c
>>> +++ b/drivers/acpi/ec.c
>>> @@ -1488,7 +1488,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>>
>>>          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);
>>> @@ -1497,7 +1497,7 @@ static int ec_install_handlers(struct acpi_ec *ec, struct acpi_device *device,
>>>                          return -ENODEV;
>>>                  }
>>>                  set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
>>> -               ec->address_space_handler_holder = ec->handle;
>>> +               ec->address_space_handler_holder = ACPI_ROOT_OBJECT;
>>>          }
>>>
>>>          if (call_reg && !test_bit(EC_FLAGS_EC_REG_CALLED, &ec->flags)) {
>>>
>> ---
>>   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;
>>
>>

Re: Missing default handler for the EmbeddedControl OpRegion

[Rafael J. Wysocki]

On Fri, May 10, 2024 at 12:32 AM Armin Wolf <W_Armin@gmx.de> wrote:
>
> Am 09.05.24 um 12:35 schrieb Hans de Goede:
>
> > Hi Rafael,
> >
> > On 5/8/24 2:50 PM, Rafael J. Wysocki wrote:
> >> [Resending because it appears to have got lost, sorry for duplicates.]
> >>
> >> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
> >>> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
> >>>> Hi,
> >>>>
> >>>> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
> >>>> <heikki.krogerus@linux.intel.com> wrote:
> >>>>> Hi,
> >>>>>
> >>>>> There's a bug that is caused by an EmbeddedControl OpRegion which is
> >>>>> declared inside the scope of a specific USB Type-C device (PNP0CA0):
> >>>>> https://bugzilla.kernel.org/show_bug.cgi?id=218789
> >>>> And in this bug you are essentially proposing to install the EC
> >>>> OpRegion handler at the namespace root instead of the EC device.
> >>>>
> >>>> This sounds reasonable, although AFAICS this is a matter of modifying
> >>>> the EC driver (before the EC OpRegion handler is installed by the EC
> >>>> drvier, ACPICA has no way to handle EC address space accesses anyway).
> >>>>
> >>>>> It looks like that's not the only case where that OpRegion ID is used
> >>>>> outside of the EC device scope. There is at least one driver in Linux
> >>>>> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
> >>>>> for the EmbeddedControl OpRegion, and based on a quick search, the
> >>>>> problem "Region EmbeddedControl (ID=3) has no handler" has happened
> >>>>> with some other devices too.
> >>>> AFAICS, installing the EC address space handler at the EC device
> >>>> object itself is not based on any sound technical arguments, it's just
> >>>> been always done this way in Linux.  It's quite possible that the EC
> >>>> address space handler should have been installed at the namespace root
> >>>> from the outset.
> >>> Okay, thank you for the explanation. So can we simply change it like
> >>> this (I may have still misunderstood something)?
> >> Roughly speaking, yes, but it is missing an analogous change around
> >> the removal.
> >>
> >> Please see the appended patch (which I have created independently in
> >> the meantime).  It doesn't break stuff for me and Andy points out that
> >> there are examples of EmbeddedControl OpRegions outside the EC device
> >> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
> >>
> >> So I think that this change can be made relatively safely (but adding Hans and
> >> Mario to the CC in case they know something that might be broken by it).
> > +Cc Armin for WMI EC handler
> >
> > No objections from me against registering the EC handler at the root,
> > when I saw that the WMI driver was registering its own handler I was
> > already wondering why we did not just register the acpi/ec.c handler at
> > the root level but I did not have time to pursue this further.
> >
> > One question which I have is does the drivers/acpi/ec.c version handle
> > read/writes of a width other then 8 bits ? Armin recently added support
> > for other widths to the WMI version of the OpRegion handler to fix
> > issues on some laptop models:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c663b26972eae7d2a614f584c92a266fe9a2d44c
> >
> > Regards,
> >
> > Hans
>
> Hi,
>
> the handling of multi-byte reads/writes was taken from the ec driver itself, so
> using the standard ec handler should make no difference for the WMI driver.

Thanks for the confirmation!

So AFAICS acpi_wmi_ec_space_handler() will not be necessary after this
change, but so long as it is installed by acpi_wmi_probe(), it will be
used for opregions in the WMI device scope, so I'd prefer to remove it
in a separate patch to avoid making too many changes in one go.

Let me add a changelog to the patch posted here

https://lore.kernel.org/linux-acpi/5781917.DvuYhMxLoT@kreacher/

and submit it properly along with a separate change removing
acpi_wmi_ec_space_handler().

Re: Missing default handler for the EmbeddedControl OpRegion

[Hans de Goede]

Hi,

On 5/10/24 12:03 PM, Rafael J. Wysocki wrote:
> On Fri, May 10, 2024 at 12:32 AM Armin Wolf <W_Armin@gmx.de> wrote:
>>
>> Am 09.05.24 um 12:35 schrieb Hans de Goede:
>>
>>> Hi Rafael,
>>>
>>> On 5/8/24 2:50 PM, Rafael J. Wysocki wrote:
>>>> [Resending because it appears to have got lost, sorry for duplicates.]
>>>>
>>>> On Wednesday, May 8, 2024 2:20:59 PM CEST Heikki Krogerus wrote:
>>>>> On Mon, May 06, 2024 at 07:45:07PM +0200, Rafael J. Wysocki wrote:
>>>>>> Hi,
>>>>>>
>>>>>> On Mon, Apr 29, 2024 at 4:55 PM Heikki Krogerus
>>>>>> <heikki.krogerus@linux.intel.com> wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> There's a bug that is caused by an EmbeddedControl OpRegion which is
>>>>>>> declared inside the scope of a specific USB Type-C device (PNP0CA0):
>>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=218789
>>>>>> And in this bug you are essentially proposing to install the EC
>>>>>> OpRegion handler at the namespace root instead of the EC device.
>>>>>>
>>>>>> This sounds reasonable, although AFAICS this is a matter of modifying
>>>>>> the EC driver (before the EC OpRegion handler is installed by the EC
>>>>>> drvier, ACPICA has no way to handle EC address space accesses anyway).
>>>>>>
>>>>>>> It looks like that's not the only case where that OpRegion ID is used
>>>>>>> outside of the EC device scope. There is at least one driver in Linux
>>>>>>> Kernel (drivers/platform/x86/wmi.c) that already has a custom handler
>>>>>>> for the EmbeddedControl OpRegion, and based on a quick search, the
>>>>>>> problem "Region EmbeddedControl (ID=3) has no handler" has happened
>>>>>>> with some other devices too.
>>>>>> AFAICS, installing the EC address space handler at the EC device
>>>>>> object itself is not based on any sound technical arguments, it's just
>>>>>> been always done this way in Linux.  It's quite possible that the EC
>>>>>> address space handler should have been installed at the namespace root
>>>>>> from the outset.
>>>>> Okay, thank you for the explanation. So can we simply change it like
>>>>> this (I may have still misunderstood something)?
>>>> Roughly speaking, yes, but it is missing an analogous change around
>>>> the removal.
>>>>
>>>> Please see the appended patch (which I have created independently in
>>>> the meantime).  It doesn't break stuff for me and Andy points out that
>>>> there are examples of EmbeddedControl OpRegions outside the EC device
>>>> scope in the spec (see Section 9.17.15 in ACPI 6.5, for instance).
>>>>
>>>> So I think that this change can be made relatively safely (but adding Hans and
>>>> Mario to the CC in case they know something that might be broken by it).
>>> +Cc Armin for WMI EC handler
>>>
>>> No objections from me against registering the EC handler at the root,
>>> when I saw that the WMI driver was registering its own handler I was
>>> already wondering why we did not just register the acpi/ec.c handler at
>>> the root level but I did not have time to pursue this further.
>>>
>>> One question which I have is does the drivers/acpi/ec.c version handle
>>> read/writes of a width other then 8 bits ? Armin recently added support
>>> for other widths to the WMI version of the OpRegion handler to fix
>>> issues on some laptop models:
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c663b26972eae7d2a614f584c92a266fe9a2d44c
>>>
>>> Regards,
>>>
>>> Hans
>>
>> Hi,
>>
>> the handling of multi-byte reads/writes was taken from the ec driver itself, so
>> using the standard ec handler should make no difference for the WMI driver.
> 
> Thanks for the confirmation!
> 
> So AFAICS acpi_wmi_ec_space_handler() will not be necessary after this
> change, but so long as it is installed by acpi_wmi_probe(), it will be
> used for opregions in the WMI device scope, so I'd prefer to remove it
> in a separate patch to avoid making too many changes in one go.

Ack.

> Let me add a changelog to the patch posted here
> 
> https://lore.kernel.org/linux-acpi/5781917.DvuYhMxLoT@kreacher/
> 
> and submit it properly along with a separate change removing
> acpi_wmi_ec_space_handler().

This sounds good to me.

Regards,

Hans