[PATCH v1] backlight: apple_bl: Convert to a platform driver

[PATCH v1] backlight: apple_bl: Convert to a platform driver

[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 Apple Backlight 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.

Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/video/backlight/apple_bl.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/video/backlight/apple_bl.c b/drivers/video/backlight/apple_bl.c
index aaa824437a2a..423513d68b5b 100644
--- a/drivers/video/backlight/apple_bl.c
+++ b/drivers/video/backlight/apple_bl.c
@@ -24,6 +24,7 @@
 #include <linux/pci.h>
 #include <linux/acpi.h>
 #include <linux/atomic.h>
+#include <linux/platform_device.h>
 #include <acpi/video.h>
 
 static struct backlight_device *apple_backlight_device;
@@ -134,7 +135,7 @@ static const struct hw_data nvidia_chipset_data = {
 	.set_brightness = nvidia_chipset_set_brightness,
 };
 
-static int apple_bl_add(struct acpi_device *dev)
+static int apple_bl_probe(struct platform_device *pdev)
 {
 	struct backlight_properties props;
 	struct pci_dev *host;
@@ -193,7 +194,7 @@ static int apple_bl_add(struct acpi_device *dev)
 	return 0;
 }
 
-static void apple_bl_remove(struct acpi_device *dev)
+static void apple_bl_remove(struct platform_device *pdev)
 {
 	backlight_device_unregister(apple_backlight_device);
 
@@ -206,12 +207,12 @@ static const struct acpi_device_id apple_bl_ids[] = {
 	{"", 0},
 };
 
-static struct acpi_driver apple_bl_driver = {
-	.name = "Apple backlight",
-	.ids = apple_bl_ids,
-	.ops = {
-		.add = apple_bl_add,
-		.remove = apple_bl_remove,
+static struct platform_driver apple_bl_driver = {
+	.probe = apple_bl_probe,
+	.remove = apple_bl_remove,
+	.driver = {
+		.name = "Apple backlight",
+		.acpi_match_table = apple_bl_ids,
 	},
 };
 
@@ -224,12 +225,12 @@ static int __init apple_bl_init(void)
 	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
 		return -ENODEV;
 
-	return acpi_bus_register_driver(&apple_bl_driver);
+	return platform_driver_register(&apple_bl_driver);
 }
 
 static void __exit apple_bl_exit(void)
 {
-	acpi_bus_unregister_driver(&apple_bl_driver);
+	platform_driver_unregister(&apple_bl_driver);
 }
 
 module_init(apple_bl_init);
-- 
2.51.0

Re: [PATCH v1] backlight: apple_bl: Convert to a platform driver

[Daniel Thompson]

On Sat, Mar 14, 2026 at 12:50:11PM +0100, Rafael J. Wysocki wrote:
> 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 Apple Backlight 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.
>
> Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.

Re: [PATCH v1] backlight: apple_bl: Convert to a platform driver

[Rafael J. Wysocki]

On Mon, Mar 23, 2026 at 10:57 AM Daniel Thompson <danielt@kernel.org> wrote:
>
> On Sat, Mar 14, 2026 at 12:50:11PM +0100, Rafael J. Wysocki wrote:
> > 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 Apple Backlight 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.
> >
> > Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>

Thanks!

Unless anyone has any objections or concerns (in which case please let
me know), I'm going to queue up this one for 7.1.

Re: [PATCH v1] backlight: apple_bl: Convert to a platform driver

[Lee Jones]

On Tue, 24 Mar 2026, Rafael J. Wysocki wrote:

> On Mon, Mar 23, 2026 at 10:57 AM Daniel Thompson <danielt@kernel.org> wrote:
> >
> > On Sat, Mar 14, 2026 at 12:50:11PM +0100, Rafael J. Wysocki wrote:
> > > 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 Apple Backlight 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.
> > >
> > > Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
> 
> Thanks!
> 
> Unless anyone has any objections or concerns (in which case please let
> me know), I'm going to queue up this one for 7.1.

Why would you queue-up a Backlight patch?

I'd rather this goes in via the Backlight tree.

-- 
Lee Jones [李琼斯]

Re: [PATCH v1] backlight: apple_bl: Convert to a platform driver

[Rafael J. Wysocki]

On Tue, Mar 24, 2026 at 5:40 PM Lee Jones <lee@kernel.org> wrote:
>
> On Tue, 24 Mar 2026, Rafael J. Wysocki wrote:
>
> > On Mon, Mar 23, 2026 at 10:57 AM Daniel Thompson <danielt@kernel.org> wrote:
> > >
> > > On Sat, Mar 14, 2026 at 12:50:11PM +0100, Rafael J. Wysocki wrote:
> > > > 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 Apple Backlight 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.
> > > >
> > > > Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/ [1]
> > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
> >
> > Thanks!
> >
> > Unless anyone has any objections or concerns (in which case please let
> > me know), I'm going to queue up this one for 7.1.
>
> Why would you queue-up a Backlight patch?

Because I care about this change and it's mostly about ACPI.

> I'd rather this goes in via the Backlight tree.

Sure, no problem with that.