[PATCH v4 0/5] platform/x86: panasonic-laptop: Bind to a platform device instead of an ACPI one

[PATCH v4 0/5] platform/x86: panasonic-laptop: Bind to a platform device instead of an ACPI one

[Rafael J. Wysocki]

Hi All,

This is an update of

https://lore.kernel.org/linux-acpi/12863246.O9o76ZdvQC@rafael.j.wysocki/

addressing a driver_data pointer leak in the last patch.  The other patches
in the series remain unchanged.

The previous series description below still applies.

This series is part of a larger effort to switch over all drivers using
the struct acpi_driver interface to the more common struct platform_driver
interface and eliminate the former.  The background is explained in
Documentation/driver-api/acpi/acpi-drivers.rst and in the changelog of
the patch that introduced the above document:

https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/

The bottom line is that the kernel would be better off without struct
acpi_driver and so it is better to get rid of it.

This series carries out driver conversion of the platform x86 Panasonic
hotkey and LCD brightness control driver.

Patch [1/5] changes one function return type to void.

Patch [2/5] fixes the rollback path in acpi_pcc_hotkey_add() and rearranges
the driver removal code ordering to match it.

Patch [3/5] removes some redundant checks from the driver.

Patch [4/5] updates the driver to install an ACPI notify handler by itself
instead of using the .notify() callback from struct acpi_driver, which is
requisite for the driver conversion.

Patch [5/5] converts the driver to using struct platform_driver for device
binding.

Thanks!

[PATCH v4 1/5] platform/x86: panasonic-laptop: Make pcc_register_optd_notifier() void

[Rafael J. Wysocki]

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

Convert pcc_register_optd_notifier() whose return value is never used to
a void function.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v3 -> v4: No changes

v2 -> v3: New patch

---
 drivers/platform/x86/panasonic-laptop.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index d923ddaa4849..a481f2602ce3 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -891,7 +891,7 @@ static void pcc_optd_notify(acpi_handle handle, u32 event, void *data)
 	set_optd_power_state(0);
 }
 
-static int pcc_register_optd_notifier(struct pcc_acpi *pcc, char *node)
+static void pcc_register_optd_notifier(struct pcc_acpi *pcc, char *node)
 {
 	acpi_status status;
 	acpi_handle handle;
@@ -904,10 +904,7 @@ static int pcc_register_optd_notifier(struct pcc_acpi *pcc, char *node)
 				pcc_optd_notify, pcc);
 		if (ACPI_FAILURE(status))
 			pr_err("Failed to register notify on %s\n", node);
-	} else
-		return -ENODEV;
-
-	return 0;
+	}
 }
 
 static void pcc_unregister_optd_notifier(struct pcc_acpi *pcc, char *node)
-- 
2.51.0

[PATCH v4 2/5] platform/x86: panasonic-laptop: Fix OPTD notifier registration and cleanup

[Rafael J. Wysocki]

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

An ACPI notify handler is leaked if device_create_file() returns an
error in acpi_pcc_hotkey_add().

Also, it is pointless to call pcc_unregister_optd_notifier() in
acpi_pcc_hotkey_remove() if pcc->platform is NULL and it is better
to arrange the cleanup code in that function in the same order as
the rollback code in acpi_pcc_hotkey_add().

Address the above by placing the pcc_register_optd_notifier() call in
acpi_pcc_hotkey_add() after the device_create_file() return value
check and placing the pcc_unregister_optd_notifier() call in
acpi_pcc_hotkey_remove() right before the device_remove_file() call.

Fixes: d5a81d8e864b ("platform/x86: panasonic-laptop: Add support for optical driver power in Y and W series")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v3 -> v4: No changes

v2 -> v3: Do not fail probing on OPTD registration errors (note that it is
   not a bug to attempt to unregister an ACPI notify handler that has not
   been registered)

v1 -> v2: New patch

---
 drivers/platform/x86/panasonic-laptop.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index a481f2602ce3..56b4e61d7e5c 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -1090,9 +1090,10 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 		}
 		result = device_create_file(&pcc->platform->dev,
 			&dev_attr_cdpower);
-		pcc_register_optd_notifier(pcc, "\\_SB.PCI0.EHCI.ERHB.OPTD");
 		if (result)
 			goto out_platform;
+
+		pcc_register_optd_notifier(pcc, "\\_SB.PCI0.EHCI.ERHB.OPTD");
 	} else {
 		pcc->platform = NULL;
 	}
@@ -1126,10 +1127,10 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
 	i8042_remove_filter(panasonic_i8042_filter);
 
 	if (pcc->platform) {
+		pcc_unregister_optd_notifier(pcc, "\\_SB.PCI0.EHCI.ERHB.OPTD");
 		device_remove_file(&pcc->platform->dev, &dev_attr_cdpower);
 		platform_device_unregister(pcc->platform);
 	}
-	pcc_unregister_optd_notifier(pcc, "\\_SB.PCI0.EHCI.ERHB.OPTD");
 
 	sysfs_remove_group(&device->dev.kobj, &pcc_attr_group);
 
-- 
2.51.0

[PATCH v4 3/5] platform/x86: panasonic-laptop: Remove redundant checks from 3 functions

[Rafael J. Wysocki]

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

The device pointer cannot be NULL in acpi_pcc_hotkey_add() and
acpi_pcc_hotkey_remove() because these functions are ACPI driver
callbacks and NULL is never passed to any of them as an argument.

Likewise, acpi_pcc_hotkey_resume() is a resume callback of a
device driver and NULL is never passed to it as an argument, so
the dev pointer in it cannot be NULL.

Moreover, since acpi_pcc_hotkey_remove() and acpi_pcc_hotkey_resume()
can only run after acpi_pcc_hotkey_add() has completed successfully,
the acpi_driver_data() of the device object used by them cannot be
NULL when they run.

Drop all of the redundant NULL checks of the pointers mentioned above.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v4: No changes

---
 drivers/platform/x86/panasonic-laptop.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index 56b4e61d7e5c..188ec597a14e 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -965,14 +965,7 @@ static int acpi_pcc_init_input(struct pcc_acpi *pcc)
 #ifdef CONFIG_PM_SLEEP
 static int acpi_pcc_hotkey_resume(struct device *dev)
 {
-	struct pcc_acpi *pcc;
-
-	if (!dev)
-		return -EINVAL;
-
-	pcc = acpi_driver_data(to_acpi_device(dev));
-	if (!pcc)
-		return -EINVAL;
+	struct pcc_acpi *pcc = acpi_driver_data(to_acpi_device(dev));
 
 	if (pcc->num_sifr > SINF_MUTE)
 		acpi_pcc_write_sset(pcc, SINF_MUTE, pcc->mute);
@@ -994,9 +987,6 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	struct pcc_acpi *pcc;
 	int num_sifr, result;
 
-	if (!device)
-		return -EINVAL;
-
 	num_sifr = acpi_pcc_get_sqty(device);
 
 	/*
@@ -1121,9 +1111,6 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
 {
 	struct pcc_acpi *pcc = acpi_driver_data(device);
 
-	if (!device || !pcc)
-		return;
-
 	i8042_remove_filter(panasonic_i8042_filter);
 
 	if (pcc->platform) {
-- 
2.51.0

[PATCH v4 4/5] platform/x86: panasonic-laptop: Register ACPI notify handler directly

[Rafael J. Wysocki]

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

To facilitate subsequent conversion of the driver to a platform one,
make it install an ACPI notify handler directly instead of using
a .notify() callback in struct acpi_driver.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v2 -> v4: No changes

v1 -> v2: Adjust remove code ordering to match probe rollback code
   ordering (Ilpo)

---
 drivers/platform/x86/panasonic-laptop.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index 188ec597a14e..e563298a6672 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -185,7 +185,7 @@ enum SINF_BITS { SINF_NUM_BATTERIES = 0,
 
 static int acpi_pcc_hotkey_add(struct acpi_device *device);
 static void acpi_pcc_hotkey_remove(struct acpi_device *device);
-static void acpi_pcc_hotkey_notify(struct acpi_device *device, u32 event);
+static void acpi_pcc_hotkey_notify(acpi_handle handle, u32 event, void *data);
 
 static const struct acpi_device_id pcc_device_ids[] = {
 	{ "MAT0012", 0},
@@ -208,7 +208,6 @@ static struct acpi_driver acpi_pcc_driver = {
 	.ops =		{
 				.add =		acpi_pcc_hotkey_add,
 				.remove =	acpi_pcc_hotkey_remove,
-				.notify =	acpi_pcc_hotkey_notify,
 			},
 	.drv.pm =	&acpi_pcc_hotkey_pm,
 };
@@ -869,9 +868,9 @@ static void acpi_pcc_generate_keyinput(struct pcc_acpi *pcc)
 		pr_err("Unknown hotkey event: 0x%04llx\n", result);
 }
 
-static void acpi_pcc_hotkey_notify(struct acpi_device *device, u32 event)
+static void acpi_pcc_hotkey_notify(acpi_handle handle, u32 event, void *data)
 {
-	struct pcc_acpi *pcc = acpi_driver_data(device);
+	struct pcc_acpi *pcc = data;
 
 	switch (event) {
 	case HKEY_NOTIFY:
@@ -1070,13 +1069,18 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	if (result)
 		goto out_backlight;
 
+	result = acpi_dev_install_notify_handler(device, ACPI_DEVICE_NOTIFY,
+						 acpi_pcc_hotkey_notify, pcc);
+	if (result)
+		goto out_sysfs;
+
 	/* optical drive initialization */
 	if (ACPI_SUCCESS(check_optd_present())) {
 		pcc->platform = platform_device_register_simple("panasonic",
 			PLATFORM_DEVID_NONE, NULL, 0);
 		if (IS_ERR(pcc->platform)) {
 			result = PTR_ERR(pcc->platform);
-			goto out_sysfs;
+			goto out_notify_handler;
 		}
 		result = device_create_file(&pcc->platform->dev,
 			&dev_attr_cdpower);
@@ -1093,6 +1097,9 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 
 out_platform:
 	platform_device_unregister(pcc->platform);
+out_notify_handler:
+	acpi_dev_remove_notify_handler(device, ACPI_DEVICE_NOTIFY,
+				       acpi_pcc_hotkey_notify);
 out_sysfs:
 	sysfs_remove_group(&device->dev.kobj, &pcc_attr_group);
 out_backlight:
@@ -1119,6 +1126,9 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
 		platform_device_unregister(pcc->platform);
 	}
 
+	acpi_dev_remove_notify_handler(device, ACPI_DEVICE_NOTIFY,
+				       acpi_pcc_hotkey_notify);
+
 	sysfs_remove_group(&device->dev.kobj, &pcc_attr_group);
 
 	backlight_device_unregister(pcc->backlight);
-- 
2.51.0

[PATCH v4 5/5] platform/x86: panasonic-laptop: Convert ACPI driver to a platform one

[Rafael J. Wysocki]

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

In all cases in which a struct acpi_driver is used for binding a driver
to an ACPI device object, a corresponding platform device is created by
the ACPI core and that device is regarded as a proper representation of
underlying hardware.  Accordingly, a struct platform_driver should be
used by driver code to bind to that device.  There are multiple reasons
why drivers should not bind directly to ACPI device objects [1].

Overall, it is better to bind drivers to platform devices than to their
ACPI companions, so convert the Panasonic laptop ACPI driver to a platform
one.

While this is not expected to alter functionality, it changes sysfs
layout and so it will be visible to user space.

To maintain backwards compatibility with possibly existing user space,
the sysfs attributes created by the driver under the ACPI device object
used by it are not relocated.  Accordingly, the driver will continue to
use the driver_data pointer in struct acpi_device which needs to be
cleared on driver removal.

Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v3 -> v4: Clear device->driver_data in the probe rollback path

v1 -> v3: No changes

---
 drivers/platform/x86/panasonic-laptop.c | 34 ++++++++++++++-----------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index e563298a6672..1337f7c49805 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -183,8 +183,8 @@ enum SINF_BITS { SINF_NUM_BATTERIES = 0,
 	};
 /* R1 handles SINF_AC_CUR_BRIGHT as SINF_CUR_BRIGHT, doesn't know AC state */
 
-static int acpi_pcc_hotkey_add(struct acpi_device *device);
-static void acpi_pcc_hotkey_remove(struct acpi_device *device);
+static int acpi_pcc_hotkey_probe(struct platform_device *pdev);
+static void acpi_pcc_hotkey_remove(struct platform_device *pdev);
 static void acpi_pcc_hotkey_notify(acpi_handle handle, u32 event, void *data);
 
 static const struct acpi_device_id pcc_device_ids[] = {
@@ -201,15 +201,14 @@ static int acpi_pcc_hotkey_resume(struct device *dev);
 #endif
 static SIMPLE_DEV_PM_OPS(acpi_pcc_hotkey_pm, NULL, acpi_pcc_hotkey_resume);
 
-static struct acpi_driver acpi_pcc_driver = {
-	.name =		ACPI_PCC_DRIVER_NAME,
-	.class =	ACPI_PCC_CLASS,
-	.ids =		pcc_device_ids,
-	.ops =		{
-				.add =		acpi_pcc_hotkey_add,
-				.remove =	acpi_pcc_hotkey_remove,
-			},
-	.drv.pm =	&acpi_pcc_hotkey_pm,
+static struct platform_driver acpi_pcc_driver = {
+	.probe = acpi_pcc_hotkey_probe,
+	.remove = acpi_pcc_hotkey_remove,
+	.driver = {
+		.name = ACPI_PCC_DRIVER_NAME,
+		.acpi_match_table = pcc_device_ids,
+		.pm = &acpi_pcc_hotkey_pm,
+	},
 };
 
 static const struct key_entry panasonic_keymap[] = {
@@ -964,7 +963,7 @@ static int acpi_pcc_init_input(struct pcc_acpi *pcc)
 #ifdef CONFIG_PM_SLEEP
 static int acpi_pcc_hotkey_resume(struct device *dev)
 {
-	struct pcc_acpi *pcc = acpi_driver_data(to_acpi_device(dev));
+	struct pcc_acpi *pcc = acpi_driver_data(ACPI_COMPANION(dev));
 
 	if (pcc->num_sifr > SINF_MUTE)
 		acpi_pcc_write_sset(pcc, SINF_MUTE, pcc->mute);
@@ -980,8 +979,9 @@ static int acpi_pcc_hotkey_resume(struct device *dev)
 }
 #endif
 
-static int acpi_pcc_hotkey_add(struct acpi_device *device)
+static int acpi_pcc_hotkey_probe(struct platform_device *pdev)
 {
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 	struct backlight_properties props;
 	struct pcc_acpi *pcc;
 	int num_sifr, result;
@@ -1107,6 +1107,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 out_input:
 	input_unregister_device(pcc->input_dev);
 out_sinf:
+	device->driver_data = NULL;
 	kfree(pcc->sinf);
 out_hotkey:
 	kfree(pcc);
@@ -1114,8 +1115,9 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	return result;
 }
 
-static void acpi_pcc_hotkey_remove(struct acpi_device *device)
+static void acpi_pcc_hotkey_remove(struct platform_device *pdev)
 {
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 	struct pcc_acpi *pcc = acpi_driver_data(device);
 
 	i8042_remove_filter(panasonic_i8042_filter);
@@ -1135,8 +1137,10 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
 
 	input_unregister_device(pcc->input_dev);
 
+	device->driver_data = NULL;
+
 	kfree(pcc->sinf);
 	kfree(pcc);
 }
 
-module_acpi_driver(acpi_pcc_driver);
+module_platform_driver(acpi_pcc_driver);
-- 
2.51.0

Re: [PATCH v4 0/5] platform/x86: panasonic-laptop: Bind to a platform device instead of an ACPI one

[Ilpo Järvinen]

On Fri, 20 Mar 2026 11:29:16 +0100, Rafael J. Wysocki wrote:

> This is an update of
> 
> https://lore.kernel.org/linux-acpi/12863246.O9o76ZdvQC@rafael.j.wysocki/
> 
> addressing a driver_data pointer leak in the last patch.  The other patches
> in the series remain unchanged.
> 
> [...]


Thank you for your contribution, it has been applied to my local
review-ilpo-next branch. Note it will show up in the public
platform-drivers-x86/review-ilpo-next branch only once I've pushed my
local branch there, which might take a while.

The list of commits applied:
[1/5] platform/x86: panasonic-laptop: Make pcc_register_optd_notifier() void
      commit: e2b0cd5c265f01977ed4e7f04bd989cdb0b9eaed
[2/5] platform/x86: panasonic-laptop: Fix OPTD notifier registration and cleanup
      commit: 8baeff2c1d33dad8572216c6ad3a7425852507d4
[3/5] platform/x86: panasonic-laptop: Remove redundant checks from 3 functions
      commit: a347e11252c60bfce1bf15f2f86484cdb9bf6468
[4/5] platform/x86: panasonic-laptop: Register ACPI notify handler directly
      commit: 0381b6a65716dae778fb4b5ee4ee42aca62402e9
[5/5] platform/x86: panasonic-laptop: Convert ACPI driver to a platform one
      commit: de6837243af00dc22b5117f45a35ec20adbf62c5

--
 i.