[PATCH v2 0/3] ACPI: video/apple-gmux: Fix apple gmux backlight detection

[PATCH v2 0/3] ACPI: video/apple-gmux: Fix apple gmux backlight detection

[Hans de Goede]

Hi All,

Here is v2 of my series to fix apple-gmux detection in
the acpi_video_get_backlight_type() function.

Changes in v2:
- Fix leaking of adev reference returned by acpi_dev_get_first_match_dev()
  (Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>)
- Add list of known affected Apple models (Lukas Wunner)
- Add Reported-by and Link tags

Most of the changes are in the commit messages. Here is the actual code-diff
between v1 and v2 for fixing the adev leak:

--- a/include/linux/apple-gmux.h
+++ b/include/linux/apple-gmux.h
@@ -68,18 +68,19 @@ static inline bool apple_gmux_is_indexed(unsigned long iostart)
 static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
 {
 	u8 ver_major, ver_minor, ver_release;
+	struct device *dev = NULL;
+	struct acpi_device *adev;
 	struct resource *res;
 	bool indexed = false;
+	bool ret = false;
 
 	if (!pnp_dev) {
-		struct acpi_device *adev;
-		struct device *dev;
-
 		adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
 		if (!adev)
 			return false;
 
-		dev = acpi_get_first_physical_node(adev);
+		dev = get_device(acpi_get_first_physical_node(adev));
+		acpi_dev_put(adev);
 		if (!dev)
 			return false;
 
@@ -87,11 +88,8 @@ static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
 	}
 
 	res = pnp_get_resource(pnp_dev, IORESOURCE_IO, 0);
-	if (!res)
-		return false;
-
-	if (resource_size(res) < GMUX_MIN_IO_LEN)
-		return false;
+	if (!res || resource_size(res) < GMUX_MIN_IO_LEN)
+		goto out;
 
 	/*
 	 * Invalid version information may indicate either that the gmux
@@ -103,13 +101,16 @@ static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
 	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
 		indexed = apple_gmux_is_indexed(res->start);
 		if (!indexed)
-			return false;
+			goto out;
 	}
 
 	if (indexed_ret)
 		*indexed_ret = indexed;
 
-	return true;
+	ret = true;
+out:
+	put_device(dev);
+	return ret;
 }
 
 /**

Thank you Andy for pointing out this leak.

Note I plan to push this v2 to pdx86/fixes pretty much straight away after
sending this out, to give the builders some time to play with it. And then
if there is no negative feedback on this I'll include this in a fixes
pull-req to Linus later this week.

Regards,

Hans



Hans de Goede (3):
  platform/x86: apple-gmux: Move port defines to apple-gmux.h
  platform/x86: apple-gmux: Add apple_gmux_detect() helper
  ACPI: video: Fix apple gmux detection

 drivers/acpi/video_detect.c       |  24 +------
 drivers/platform/x86/apple-gmux.c |  93 +++++--------------------
 include/linux/apple-gmux.h        | 109 +++++++++++++++++++++++++++++-
 3 files changed, 128 insertions(+), 98 deletions(-)

-- 
2.39.0

[PATCH v2 1/3] platform/x86: apple-gmux: Move port defines to apple-gmux.h

[Hans de Goede]

This is a preparation patch for adding a new static inline
apple_gmux_detect() helper which actually checks a supported
gmux is present, rather then only checking an ACPI device with
the HID is there as apple_gmux_present() does.

Fixes: 21245df307cb ("ACPI: video: Add Apple GMUX brightness control detection")
Link: https://lore.kernel.org/platform-driver-x86/20230123113750.462144-1-hdegoede@redhat.com/
Reported-by: Emmanouil Kouroupakis <kartebi@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/apple-gmux.c | 23 -----------------------
 include/linux/apple-gmux.h        | 23 +++++++++++++++++++++++
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index ca33df7ea550..a0af01f6a0fd 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -64,29 +64,6 @@ struct apple_gmux_data {
 
 static struct apple_gmux_data *apple_gmux_data;
 
-/*
- * gmux port offsets. Many of these are not yet used, but may be in the
- * future, and it's useful to have them documented here anyhow.
- */
-#define GMUX_PORT_VERSION_MAJOR		0x04
-#define GMUX_PORT_VERSION_MINOR		0x05
-#define GMUX_PORT_VERSION_RELEASE	0x06
-#define GMUX_PORT_SWITCH_DISPLAY	0x10
-#define GMUX_PORT_SWITCH_GET_DISPLAY	0x11
-#define GMUX_PORT_INTERRUPT_ENABLE	0x14
-#define GMUX_PORT_INTERRUPT_STATUS	0x16
-#define GMUX_PORT_SWITCH_DDC		0x28
-#define GMUX_PORT_SWITCH_EXTERNAL	0x40
-#define GMUX_PORT_SWITCH_GET_EXTERNAL	0x41
-#define GMUX_PORT_DISCRETE_POWER	0x50
-#define GMUX_PORT_MAX_BRIGHTNESS	0x70
-#define GMUX_PORT_BRIGHTNESS		0x74
-#define GMUX_PORT_VALUE			0xc2
-#define GMUX_PORT_READ			0xd0
-#define GMUX_PORT_WRITE			0xd4
-
-#define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)
-
 #define GMUX_INTERRUPT_ENABLE		0xff
 #define GMUX_INTERRUPT_DISABLE		0x00
 
diff --git a/include/linux/apple-gmux.h b/include/linux/apple-gmux.h
index ddb10aa67b14..80efaaf89e07 100644
--- a/include/linux/apple-gmux.h
+++ b/include/linux/apple-gmux.h
@@ -11,6 +11,29 @@
 
 #define GMUX_ACPI_HID "APP000B"
 
+/*
+ * gmux port offsets. Many of these are not yet used, but may be in the
+ * future, and it's useful to have them documented here anyhow.
+ */
+#define GMUX_PORT_VERSION_MAJOR		0x04
+#define GMUX_PORT_VERSION_MINOR		0x05
+#define GMUX_PORT_VERSION_RELEASE	0x06
+#define GMUX_PORT_SWITCH_DISPLAY	0x10
+#define GMUX_PORT_SWITCH_GET_DISPLAY	0x11
+#define GMUX_PORT_INTERRUPT_ENABLE	0x14
+#define GMUX_PORT_INTERRUPT_STATUS	0x16
+#define GMUX_PORT_SWITCH_DDC		0x28
+#define GMUX_PORT_SWITCH_EXTERNAL	0x40
+#define GMUX_PORT_SWITCH_GET_EXTERNAL	0x41
+#define GMUX_PORT_DISCRETE_POWER	0x50
+#define GMUX_PORT_MAX_BRIGHTNESS	0x70
+#define GMUX_PORT_BRIGHTNESS		0x74
+#define GMUX_PORT_VALUE			0xc2
+#define GMUX_PORT_READ			0xd0
+#define GMUX_PORT_WRITE			0xd4
+
+#define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)
+
 #if IS_ENABLED(CONFIG_APPLE_GMUX)
 
 /**
-- 
2.39.0

[PATCH v2 2/3] platform/x86: apple-gmux: Add apple_gmux_detect() helper

[Hans de Goede]

Add a new (static inline) apple_gmux_detect() helper to apple-gmux.h
which can be used for gmux detection instead of apple_gmux_present().

The latter is not really reliable since an ACPI device with a HID
of APP000B is present on some devices without a gmux at all, as well
as on devices with a newer (unsupported) MMIO based gmux model.

This causes apple_gmux_present() to return false-positives on
a number of different Apple laptop models.

This new helper uses the same probing as the actual apple-gmux
driver, so that it does not return false positives.

To avoid code duplication the gmux_probe() function of the actual
driver is also moved over to using the new apple_gmux_detect() helper.

This avoids false positives (vs _HID + IO region detection) on:

MacBookPro5,4
https://pastebin.com/8Xjq7RhS

MacBookPro8,1
https://linux-hardware.org/?probe=e513cfbadb&log=dmesg

MacBookPro9,2
https://bugzilla.kernel.org/attachment.cgi?id=278961

MacBookPro10,2
https://lkml.org/lkml/2014/9/22/657

MacBookPro11,2
https://forums.fedora-fr.org/viewtopic.php?id=70142

MacBookPro11,4
https://raw.githubusercontent.com/im-0/investigate-card-reader-suspend-problem-on-mbp11.4/master/test-16/dmesg

Fixes: 21245df307cb ("ACPI: video: Add Apple GMUX brightness control detection")
Link: https://lore.kernel.org/platform-driver-x86/20230123113750.462144-1-hdegoede@redhat.com/
Reported-by: Emmanouil Kouroupakis <kartebi@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
- Fix leaking of adev reference returned by acpi_dev_get_first_match_dev()
  (Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>)
- Add list of known affected Apple models (Lukas Wunner)
- Add Reported-by and Link tags
---
 drivers/platform/x86/apple-gmux.c | 70 +++++++------------------
 include/linux/apple-gmux.h        | 86 ++++++++++++++++++++++++++++++-
 2 files changed, 102 insertions(+), 54 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index a0af01f6a0fd..9333f82cfa8a 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -226,23 +226,6 @@ static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
 		gmux_pio_write32(gmux_data, port, val);
 }
 
-static bool gmux_is_indexed(struct apple_gmux_data *gmux_data)
-{
-	u16 val;
-
-	outb(0xaa, gmux_data->iostart + 0xcc);
-	outb(0x55, gmux_data->iostart + 0xcd);
-	outb(0x00, gmux_data->iostart + 0xce);
-
-	val = inb(gmux_data->iostart + 0xcc) |
-		(inb(gmux_data->iostart + 0xcd) << 8);
-
-	if (val == 0x55aa)
-		return true;
-
-	return false;
-}
-
 /**
  * DOC: Backlight control
  *
@@ -582,60 +565,43 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
 	int ret = -ENXIO;
 	acpi_status status;
 	unsigned long long gpe;
+	bool indexed = false;
+	u32 version;
 
 	if (apple_gmux_data)
 		return -EBUSY;
 
+	if (!apple_gmux_detect(pnp, &indexed)) {
+		pr_info("gmux device not present\n");
+		return -ENODEV;
+	}
+
 	gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
 	if (!gmux_data)
 		return -ENOMEM;
 	pnp_set_drvdata(pnp, gmux_data);
 
 	res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
-	if (!res) {
-		pr_err("Failed to find gmux I/O resource\n");
-		goto err_free;
-	}
-
 	gmux_data->iostart = res->start;
 	gmux_data->iolen = resource_size(res);
 
-	if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
-		pr_err("gmux I/O region too small (%lu < %u)\n",
-		       gmux_data->iolen, GMUX_MIN_IO_LEN);
-		goto err_free;
-	}
-
 	if (!request_region(gmux_data->iostart, gmux_data->iolen,
 			    "Apple gmux")) {
 		pr_err("gmux I/O already in use\n");
 		goto err_free;
 	}
 
-	/*
-	 * Invalid version information may indicate either that the gmux
-	 * device isn't present or that it's a new one that uses indexed
-	 * io
-	 */
-
-	ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
-	ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
-	ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
-	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
-		if (gmux_is_indexed(gmux_data)) {
-			u32 version;
-			mutex_init(&gmux_data->index_lock);
-			gmux_data->indexed = true;
-			version = gmux_read32(gmux_data,
-				GMUX_PORT_VERSION_MAJOR);
-			ver_major = (version >> 24) & 0xff;
-			ver_minor = (version >> 16) & 0xff;
-			ver_release = (version >> 8) & 0xff;
-		} else {
-			pr_info("gmux device not present\n");
-			ret = -ENODEV;
-			goto err_release;
-		}
+	if (indexed) {
+		mutex_init(&gmux_data->index_lock);
+		gmux_data->indexed = true;
+		version = gmux_read32(gmux_data, GMUX_PORT_VERSION_MAJOR);
+		ver_major = (version >> 24) & 0xff;
+		ver_minor = (version >> 16) & 0xff;
+		ver_release = (version >> 8) & 0xff;
+	} else {
+		ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
+		ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
+		ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
 	}
 	pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
 		ver_release, (gmux_data->indexed ? "indexed" : "classic"));
diff --git a/include/linux/apple-gmux.h b/include/linux/apple-gmux.h
index 80efaaf89e07..1f68b49bcd68 100644
--- a/include/linux/apple-gmux.h
+++ b/include/linux/apple-gmux.h
@@ -8,6 +8,8 @@
 #define LINUX_APPLE_GMUX_H
 
 #include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/pnp.h>
 
 #define GMUX_ACPI_HID "APP000B"
 
@@ -35,14 +37,89 @@
 #define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)
 
 #if IS_ENABLED(CONFIG_APPLE_GMUX)
+static inline bool apple_gmux_is_indexed(unsigned long iostart)
+{
+	u16 val;
+
+	outb(0xaa, iostart + 0xcc);
+	outb(0x55, iostart + 0xcd);
+	outb(0x00, iostart + 0xce);
+
+	val = inb(iostart + 0xcc) | (inb(iostart + 0xcd) << 8);
+	if (val == 0x55aa)
+		return true;
+
+	return false;
+}
 
 /**
- * apple_gmux_present() - detect if gmux is built into the machine
+ * apple_gmux_detect() - detect if gmux is built into the machine
+ *
+ * @pnp_dev:     Device to probe or NULL to use the first matching device
+ * @indexed_ret: Returns (by reference) if the gmux is indexed or not
+ *
+ * Detect if a supported gmux device is present by actually probing it.
+ * This avoids the false positives returned on some models by
+ * apple_gmux_present().
+ *
+ * Return: %true if a supported gmux ACPI device is detected and the kernel
+ * was configured with CONFIG_APPLE_GMUX, %false otherwise.
+ */
+static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
+{
+	u8 ver_major, ver_minor, ver_release;
+	struct device *dev = NULL;
+	struct acpi_device *adev;
+	struct resource *res;
+	bool indexed = false;
+	bool ret = false;
+
+	if (!pnp_dev) {
+		adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
+		if (!adev)
+			return false;
+
+		dev = get_device(acpi_get_first_physical_node(adev));
+		acpi_dev_put(adev);
+		if (!dev)
+			return false;
+
+		pnp_dev = to_pnp_dev(dev);
+	}
+
+	res = pnp_get_resource(pnp_dev, IORESOURCE_IO, 0);
+	if (!res || resource_size(res) < GMUX_MIN_IO_LEN)
+		goto out;
+
+	/*
+	 * Invalid version information may indicate either that the gmux
+	 * device isn't present or that it's a new one that uses indexed io.
+	 */
+	ver_major = inb(res->start + GMUX_PORT_VERSION_MAJOR);
+	ver_minor = inb(res->start + GMUX_PORT_VERSION_MINOR);
+	ver_release = inb(res->start + GMUX_PORT_VERSION_RELEASE);
+	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
+		indexed = apple_gmux_is_indexed(res->start);
+		if (!indexed)
+			goto out;
+	}
+
+	if (indexed_ret)
+		*indexed_ret = indexed;
+
+	ret = true;
+out:
+	put_device(dev);
+	return ret;
+}
+
+/**
+ * apple_gmux_present() - check if gmux ACPI device is present
  *
  * Drivers may use this to activate quirks specific to dual GPU MacBook Pros
  * and Mac Pros, e.g. for deferred probing, runtime pm and backlight.
  *
- * Return: %true if gmux is present and the kernel was configured
+ * Return: %true if gmux ACPI device is present and the kernel was configured
  * with CONFIG_APPLE_GMUX, %false otherwise.
  */
 static inline bool apple_gmux_present(void)
@@ -57,6 +134,11 @@ static inline bool apple_gmux_present(void)
 	return false;
 }
 
+static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
+{
+	return false;
+}
+
 #endif /* !CONFIG_APPLE_GMUX */
 
 #endif /* LINUX_APPLE_GMUX_H */
-- 
2.39.0

[PATCH v2 3/3] ACPI: video: Fix apple gmux detection

[Hans de Goede]

Some apple laptop models have an ACPI device with a HID of APP000B
and that device has an IO resource (so it does not describe the new
unsupported MMIO based gmux type), but there actually is no gmux
in the laptop at all.

The gmux_probe() function of the actual apple-gmux driver has code
to detect this, this code has been factored out into a new
apple_gmux_detect() helper in apple-gmux.h.

Use this new function to fix acpi_video_get_backlight_type() wrongly
returning apple_gmux as type on the following laptops:

MacBookPro5,4
https://pastebin.com/8Xjq7RhS

MacBookPro8,1
https://linux-hardware.org/?probe=e513cfbadb&log=dmesg

MacBookPro9,2
https://bugzilla.kernel.org/attachment.cgi?id=278961

MacBookPro10,2
https://lkml.org/lkml/2014/9/22/657

MacBookPro11,2
https://forums.fedora-fr.org/viewtopic.php?id=70142

MacBookPro11,4
https://raw.githubusercontent.com/im-0/investigate-card-reader-suspend-problem-on-mbp11.4/mast

Fixes: 21245df307cb ("ACPI: video: Add Apple GMUX brightness control detection")
Link: https://lore.kernel.org/platform-driver-x86/20230123113750.462144-1-hdegoede@redhat.com/
Reported-by: Emmanouil Kouroupakis <kartebi@gmail.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
- Add list of known affected Apple models (Lukas Wunner)
- Add Reported-by and Link tags
---
 drivers/acpi/video_detect.c | 24 +++---------------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 64eab35037c3..a8c02608dde4 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -110,26 +110,6 @@ static bool nvidia_wmi_ec_supported(void)
 }
 #endif
 
-static bool apple_gmux_backlight_present(void)
-{
-	struct acpi_device *adev;
-	struct device *dev;
-
-	adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
-	if (!adev)
-		return false;
-
-	dev = acpi_get_first_physical_node(adev);
-	if (!dev)
-		return false;
-
-	/*
-	 * drivers/platform/x86/apple-gmux.c only supports old style
-	 * Apple GMUX with an IO-resource.
-	 */
-	return pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
-}
-
 /* Force to use vendor driver when the ACPI device is known to be
  * buggy */
 static int video_detect_force_vendor(const struct dmi_system_id *d)
@@ -791,6 +771,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 {
 	static DEFINE_MUTEX(init_mutex);
 	static bool nvidia_wmi_ec_present;
+	static bool apple_gmux_present;
 	static bool native_available;
 	static bool init_done;
 	static long video_caps;
@@ -804,6 +785,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 				    ACPI_UINT32_MAX, find_video, NULL,
 				    &video_caps, NULL);
 		nvidia_wmi_ec_present = nvidia_wmi_ec_supported();
+		apple_gmux_present = apple_gmux_detect(NULL, NULL);
 		init_done = true;
 	}
 	if (native)
@@ -825,7 +807,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 	if (nvidia_wmi_ec_present)
 		return acpi_backlight_nvidia_wmi_ec;
 
-	if (apple_gmux_backlight_present())
+	if (apple_gmux_present)
 		return acpi_backlight_apple_gmux;
 
 	/* Use ACPI video if available, except when native should be preferred. */
-- 
2.39.0