[PATCH v1 0/4] ACPI: Add and use acpi_dev_get_pci_dev()

[PATCH v1 0/4] ACPI: Add and use acpi_dev_get_pci_dev()

[Rafael J. Wysocki]

Hi All,

This series is based on the observation that the majority of acpi_get_pci_dev()
callers already know the ACPI device they want to look up the PCI device for
and so they don't need to look up the ACPI device.  Accordingly, a function for
PCI device lookup based on an ACPI device is introduced and used.

The first patch is a simplification utilizing a mutex guard.

The second patch introduces acpi_dev_get_pci_dev() and redefines
acpi_get_pci_dev() as a static inline helper.

The third patch moves a device_put() call in the ACPI video bus driver to
a place after the device in question has been used.

The last patch updates the ACPI video bus driver, which is the heaviest user
of acpi_get_pci_dev(), to use acpi_dev_get_pci_dev() instead of it.

Thanks!

[PATCH v1 1/4] ACPI: PCI: Use a mutex guard to simplify acpi_get_pci_dev()

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Use a mutex guard in acpi_get_pci_dev() for the physical_node_lock
locking and drop local variable pci_dev that becomes redundant after
that change.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/pci_root.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -307,24 +307,20 @@ struct pci_dev *acpi_get_pci_dev(acpi_ha
 {
 	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
 	struct acpi_device_physical_node *pn;
-	struct pci_dev *pci_dev = NULL;
 
 	if (!adev)
 		return NULL;
 
-	mutex_lock(&adev->physical_node_lock);
+	guard(mutex)(&adev->physical_node_lock);
 
 	list_for_each_entry(pn, &adev->physical_node_list, node) {
 		if (dev_is_pci(pn->dev)) {
 			get_device(pn->dev);
-			pci_dev = to_pci_dev(pn->dev);
-			break;
+			return to_pci_dev(pn->dev);
 		}
 	}
 
-	mutex_unlock(&adev->physical_node_lock);
-
-	return pci_dev;
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
 

[PATCH v1 2/4] ACPI: PCI: Introduce acpi_dev_get_pci_dev()

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Some acpi_get_pci_dev() callers already have a struct ACPI device for
which they want to get the struct pci_dev pointer of the associated
PCI device, so they don't need to look for one.

For this reason, add acpi_dev_get_pci_dev() that will get a PCI device
for a given ACPI one (if possible) and turn acpi_get_pci_dev() into
a static inline helper passing the acpi_fetch_acpi_dev() return value
directly to acpi_dev_get_pci_dev().

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/pci_root.c     |   22 +++++++++++-----------
 include/acpi/acpi_drivers.h |    9 +++++++--
 2 files changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -292,20 +292,20 @@ struct acpi_pci_root *acpi_pci_find_root
 EXPORT_SYMBOL_GPL(acpi_pci_find_root);
 
 /**
- * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
- * @handle: the handle in question
+ * acpi_dev_get_pci_dev - Get a struct pci_dev for a given ACPI device
+ * @adev: Target ACPI device.
  *
- * Given an ACPI CA handle, the desired PCI device is located in the
- * list of PCI devices.
+ * Get the first PCI device associated with @adev, if present, and bump up its
+ * reference counter.
  *
- * If the device is found, its reference count is increased and this
- * function returns a pointer to its data structure.  The caller must
- * decrement the reference count by calling pci_dev_put().
- * If no device is found, %NULL is returned.
+ * Callers are responsible for dropping the PCI device reference obtained by
+ * this function.
+ *
+ * Return: The struct pci_dev pointer of a reference-counted PCI device on
+ * success or NULL on failure.
  */
-struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
+struct pci_dev *acpi_dev_get_pci_dev(struct acpi_device *adev)
 {
-	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
 	struct acpi_device_physical_node *pn;
 
 	if (!adev)
@@ -322,7 +322,7 @@ struct pci_dev *acpi_get_pci_dev(acpi_ha
 
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
+EXPORT_SYMBOL_GPL(acpi_dev_get_pci_dev);
 
 /**
  * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
--- a/include/acpi/acpi_drivers.h
+++ b/include/acpi/acpi_drivers.h
@@ -59,14 +59,19 @@ int acpi_pci_link_free_irq(acpi_handle h
 struct pci_bus;
 
 #ifdef CONFIG_PCI
-struct pci_dev *acpi_get_pci_dev(acpi_handle);
+struct pci_dev *acpi_dev_get_pci_dev(struct acpi_device *adev);
 #else
-static inline struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
+static inline struct pci_dev *acpi_dev_get_pci_dev(struct acpi_device *adev)
 {
 	return NULL;
 }
 #endif
 
+static inline struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
+{
+	return acpi_dev_get_pci_dev(acpi_fetch_acpi_dev(handle));
+}
+
 /* Arch-defined function to add a bus to the system */
 
 struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root);

[PATCH v1 3/4] ACPI: video: Drop backlight parent device reference later

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Update acpi_video_dev_register_backlight() to put the parent device after
registering the backlight class device under it instead of attempting to
register the backlight class device under a parent that (theoretically)
may be gone at that point.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/acpi_video.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -1719,10 +1719,8 @@ static void acpi_video_dev_register_back
 
 	if (ACPI_SUCCESS(acpi_get_parent(device->dev->handle, &acpi_parent))) {
 		pdev = acpi_get_pci_dev(acpi_parent);
-		if (pdev) {
+		if (pdev)
 			parent = &pdev->dev;
-			pci_dev_put(pdev);
-		}
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
@@ -1734,6 +1732,7 @@ static void acpi_video_dev_register_back
 						      device,
 						      &acpi_backlight_ops,
 						      &props);
+	put_device(parent);
 	kfree(name);
 	if (IS_ERR(device->backlight)) {
 		device->backlight = NULL;

[PATCH v1 4/4] ACPI: video: Use acpi_dev_get_pci_dev() instead of acpi_get_pci_dev()

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

In acpi_video_bus_check() and find_video(), simply replace
acpi_get_pci_dev() with acpi_dev_get_pci_dev() that can be used
in both places because the ACPI device needed to do the lookup is
available.

In acpi_video_dev_register_backlight(), instead of doing a parent ACPI
handle lookup based on the handle of an ACPI device that is already
available, pass that ACPI device to acpi_dev_parent() which is much
more straightforward and pass the return value of the latter directly
to acpi_dev_get_pci_dev() to get the PCI device associated with it.
That allows local variable acpi_parent to be eliminated.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/acpi_video.c   |   11 ++++-------
 drivers/acpi/video_detect.c |    2 +-
 2 files changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -1048,7 +1048,7 @@ static int acpi_video_bus_check(struct a
 	if (!video)
 		return -EINVAL;
 
-	dev = acpi_get_pci_dev(video->device->handle);
+	dev = acpi_dev_get_pci_dev(video->device);
 	if (!dev)
 		return -ENODEV;
 	pci_dev_put(dev);
@@ -1702,7 +1702,6 @@ static void acpi_video_dev_register_back
 {
 	struct backlight_properties props;
 	struct pci_dev *pdev;
-	acpi_handle acpi_parent;
 	struct device *parent = NULL;
 	int result;
 	static int count;
@@ -1717,11 +1716,9 @@ static void acpi_video_dev_register_back
 		return;
 	count++;
 
-	if (ACPI_SUCCESS(acpi_get_parent(device->dev->handle, &acpi_parent))) {
-		pdev = acpi_get_pci_dev(acpi_parent);
-		if (pdev)
-			parent = &pdev->dev;
-	}
+	pdev = acpi_dev_get_pci_dev(acpi_dev_parent(device->dev));
+	if (pdev)
+		parent = &pdev->dev;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.type = BACKLIGHT_FIRMWARE;
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -73,7 +73,7 @@ find_video(acpi_handle handle, u32 lvl,
 	};
 
 	if (acpi_dev && !acpi_match_device_ids(acpi_dev, video_ids)) {
-		dev = acpi_get_pci_dev(handle);
+		dev = acpi_dev_get_pci_dev(acpi_dev);
 		if (!dev)
 			return AE_OK;
 		pci_dev_put(dev);

Re: [PATCH v1 1/4] ACPI: PCI: Use a mutex guard to simplify acpi_get_pci_dev()

[sashiko-bot]

> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Use a mutex guard in acpi_get_pci_dev() for the physical_node_lock
> locking and drop local variable pci_dev that becomes redundant after
> that change.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/5115219.31r3eYUQgx@rafael.j.wysocki?part=1

Re: [PATCH v1 2/4] ACPI: PCI: Introduce acpi_dev_get_pci_dev()

[sashiko-bot]

> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Some acpi_get_pci_dev() callers already have a struct ACPI device for
> which they want to get the struct pci_dev pointer of the associated
> PCI device, so they don't need to look for one.
> 
> For this reason, add acpi_dev_get_pci_dev() that will get a PCI device
> for a given ACPI one (if possible) and turn acpi_get_pci_dev() into
> a static inline helper passing the acpi_fetch_acpi_dev() return value
> directly to acpi_dev_get_pci_dev().
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/5115219.31r3eYUQgx@rafael.j.wysocki?part=2

Re: [PATCH v1 3/4] ACPI: video: Drop backlight parent device reference later

[sashiko-bot]

> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Update acpi_video_dev_register_backlight() to put the parent device after
> registering the backlight class device under it instead of attempting to
> register the backlight class device under a parent that (theoretically)
> may be gone at that point.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/5115219.31r3eYUQgx@rafael.j.wysocki?part=3

Re: [PATCH v1 4/4] ACPI: video: Use acpi_dev_get_pci_dev() instead of acpi_get_pci_dev()

[sashiko-bot]

> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> In acpi_video_bus_check() and find_video(), simply replace
> acpi_get_pci_dev() with acpi_dev_get_pci_dev() that can be used
> in both places because the ACPI device needed to do the lookup is
> available.
> 
> In acpi_video_dev_register_backlight(), instead of doing a parent ACPI
> handle lookup based on the handle of an ACPI device that is already
> available, pass that ACPI device to acpi_dev_parent() which is much
> more straightforward and pass the return value of the latter directly
> to acpi_dev_get_pci_dev() to get the PCI device associated with it.
> That allows local variable acpi_parent to be eliminated.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/5115219.31r3eYUQgx@rafael.j.wysocki?part=4

Re: [PATCH v1 1/4] ACPI: PCI: Use a mutex guard to simplify acpi_get_pci_dev()

[Andy Shevchenko]

On Wed, Jul 15, 2026 at 05:15:02PM +0200, Rafael J. Wysocki wrote:

> Use a mutex guard in acpi_get_pci_dev() for the physical_node_lock
> locking and drop local variable pci_dev that becomes redundant after
> that change.
> 
> No intentional functional impact.

...

> -	mutex_lock(&adev->physical_node_lock);
> +	guard(mutex)(&adev->physical_node_lock);

This needs a cleanup.h to be included (yes, I see the current inclusion block
and it's a mess :-( ).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 2/4] ACPI: PCI: Introduce acpi_dev_get_pci_dev()

[Andy Shevchenko]

On Wed, Jul 15, 2026 at 05:16:19PM +0200, Rafael J. Wysocki wrote:

> Some acpi_get_pci_dev() callers already have a struct ACPI device for
> which they want to get the struct pci_dev pointer of the associated
> PCI device, so they don't need to look for one.
> 
> For this reason, add acpi_dev_get_pci_dev() that will get a PCI device
> for a given ACPI one (if possible) and turn acpi_get_pci_dev() into
> a static inline helper passing the acpi_fetch_acpi_dev() return value
> directly to acpi_dev_get_pci_dev().

...

>  /**
> - * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
> - * @handle: the handle in question
> + * acpi_dev_get_pci_dev - Get a struct pci_dev for a given ACPI device
> + * @adev: Target ACPI device.
>   *
> - * Given an ACPI CA handle, the desired PCI device is located in the
> - * list of PCI devices.
> + * Get the first PCI device associated with @adev, if present, and bump up its

What is the meaning of the "first PCI device" in terms of ACPI specification (and
implementation in the Linux kernel)? I think it's impossible case to have more
than one object to be a companion to a PCI device. Am I wrong?

> + * reference counter.
>   *
> - * If the device is found, its reference count is increased and this
> - * function returns a pointer to its data structure.  The caller must
> - * decrement the reference count by calling pci_dev_put().
> - * If no device is found, %NULL is returned.
> + * Callers are responsible for dropping the PCI device reference obtained by
> + * this function.
> + *
> + * Return: The struct pci_dev pointer of a reference-counted PCI device on
> + * success or NULL on failure.
>   */

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 3/4] ACPI: video: Drop backlight parent device reference later

[Andy Shevchenko]

On Wed, Jul 15, 2026 at 05:19:08PM +0200, Rafael J. Wysocki wrote:

> Update acpi_video_dev_register_backlight() to put the parent device after
> registering the backlight class device under it instead of attempting to
> register the backlight class device under a parent that (theoretically)
> may be gone at that point.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 4/4] ACPI: video: Use acpi_dev_get_pci_dev() instead of acpi_get_pci_dev()

[Andy Shevchenko]

On Wed, Jul 15, 2026 at 05:21:23PM +0200, Rafael J. Wysocki wrote:

> In acpi_video_bus_check() and find_video(), simply replace
> acpi_get_pci_dev() with acpi_dev_get_pci_dev() that can be used
> in both places because the ACPI device needed to do the lookup is
> available.
> 
> In acpi_video_dev_register_backlight(), instead of doing a parent ACPI
> handle lookup based on the handle of an ACPI device that is already
> available, pass that ACPI device to acpi_dev_parent() which is much
> more straightforward and pass the return value of the latter directly
> to acpi_dev_get_pci_dev() to get the PCI device associated with it.
> That allows local variable acpi_parent to be eliminated.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

...

> +++ b/drivers/acpi/video_detect.c

>  	if (acpi_dev && !acpi_match_device_ids(acpi_dev, video_ids)) {
> -		dev = acpi_get_pci_dev(handle);
> +		dev = acpi_dev_get_pci_dev(acpi_dev);

This likely needs to be rebased on top of the series I sent?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 2/4] ACPI: PCI: Introduce acpi_dev_get_pci_dev()

[Rafael J. Wysocki (Intel)]

On Wed, Jul 15, 2026 at 5:56 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, Jul 15, 2026 at 05:16:19PM +0200, Rafael J. Wysocki wrote:
>
> > Some acpi_get_pci_dev() callers already have a struct ACPI device for
> > which they want to get the struct pci_dev pointer of the associated
> > PCI device, so they don't need to look for one.
> >
> > For this reason, add acpi_dev_get_pci_dev() that will get a PCI device
> > for a given ACPI one (if possible) and turn acpi_get_pci_dev() into
> > a static inline helper passing the acpi_fetch_acpi_dev() return value
> > directly to acpi_dev_get_pci_dev().
>
> ...
>
> >  /**
> > - * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
> > - * @handle: the handle in question
> > + * acpi_dev_get_pci_dev - Get a struct pci_dev for a given ACPI device
> > + * @adev: Target ACPI device.
> >   *
> > - * Given an ACPI CA handle, the desired PCI device is located in the
> > - * list of PCI devices.
> > + * Get the first PCI device associated with @adev, if present, and bump up its
>
> What is the meaning of the "first PCI device" in terms of ACPI specification (and
> implementation in the Linux kernel)? I think it's impossible case to have more
> than one object to be a companion to a PCI device. Am I wrong?

The ACPI specification is kind of agnostic to that.

In the kernel, there can be multiple physical devices associated with
one ACPI device object, but I agree that every PCI device has at most
one ACPI companion.

I'll drop the word "first" from this comment.

> > + * reference counter.
> >   *
> > - * If the device is found, its reference count is increased and this
> > - * function returns a pointer to its data structure.  The caller must
> > - * decrement the reference count by calling pci_dev_put().
> > - * If no device is found, %NULL is returned.
> > + * Callers are responsible for dropping the PCI device reference obtained by
> > + * this function.
> > + *
> > + * Return: The struct pci_dev pointer of a reference-counted PCI device on
> > + * success or NULL on failure.
> >   */
>
> --

Re: [PATCH v1 4/4] ACPI: video: Use acpi_dev_get_pci_dev() instead of acpi_get_pci_dev()

[Rafael J. Wysocki (Intel)]

On Wed, Jul 15, 2026 at 5:59 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, Jul 15, 2026 at 05:21:23PM +0200, Rafael J. Wysocki wrote:
>
> > In acpi_video_bus_check() and find_video(), simply replace
> > acpi_get_pci_dev() with acpi_dev_get_pci_dev() that can be used
> > in both places because the ACPI device needed to do the lookup is
> > available.
> >
> > In acpi_video_dev_register_backlight(), instead of doing a parent ACPI
> > handle lookup based on the handle of an ACPI device that is already
> > available, pass that ACPI device to acpi_dev_parent() which is much
> > more straightforward and pass the return value of the latter directly
> > to acpi_dev_get_pci_dev() to get the PCI device associated with it.
> > That allows local variable acpi_parent to be eliminated.
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Thanks!

> ...
>
> > +++ b/drivers/acpi/video_detect.c
>
> >       if (acpi_dev && !acpi_match_device_ids(acpi_dev, video_ids)) {
> > -             dev = acpi_get_pci_dev(handle);
> > +             dev = acpi_dev_get_pci_dev(acpi_dev);
>
> This likely needs to be rebased on top of the series I sent?

Probably.