Update to version 0.8, update NEWS

Reported by ArchangeGabriel, original patch by tuxoko (Issue
Bumblebee-Project/bbswitch#75)

.gitignore

@@ -5,3 +5,5 @@ Module.symvers
 *.mod.c
 *.o
 modules.order
+bbswitch-*.tar.gz
+.*.sw*

COPYING

@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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+
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+Public License instead of this License.

Makefile

@@ -5,13 +5,27 @@ KVERSION := $(shell uname -r)
 KDIR := /lib/modules/$(KVERSION)/build
 PWD := "$$(pwd)"
 
+ifdef DEBUG
+CFLAGS_$(obj-m) := -DDEBUG
+endif
+
 default:
 	$(MAKE) -C $(KDIR) M=$(PWD) modules
 
 clean:
-	$(MAKE) -C $(KDIR) M=$(PWD) clean
+	$(MAKE) O=$(PWD) -C $(KDIR) M=$(PWD) clean
 
 load:
-	-/sbin/rmmod $(modname)
-	/sbin/modprobe wmi
-	/sbin/insmod $(modname).ko
+	-rmmod $(modname)
+	insmod $(modname).ko
+
+install:
+	mkdir -p /lib/modules/$(KVERSION)/misc/$(modname)
+	install -m 0755 -o root -g root $(modname).ko /lib/modules/$(KVERSION)/misc/$(modname)
+	depmod -a
+
+uninstall:
+	rm /lib/modules/$(KVERSION)/misc/$(modname)/$(modname).ko
+	rmdir /lib/modules/$(KVERSION)/misc/$(modname)
+	rmdir /lib/modules/$(KVERSION)/misc
+	depmod -a

Makefile.dkms

@@ -13,12 +13,12 @@ src_install:
 	sed 's/#MODULE_VERSION#/$(modver)/' dkms/dkms.conf > '$(DKMS_DEST)/dkms.conf'
 
 build: src_install
-	$(DKMS) build 'bbswitch/$(modver)'
+	$(DKMS) build -m bbswitch -v $(modver)
 
 install: build
-	$(DKMS) install 'bbswitch/$(modver)'
+	$(DKMS) install -m bbswitch -v $(modver)
 
 uninstall:
-	$(DKMS) remove bbswitch/$(modver) --all
+	$(DKMS) remove -m bbswitch -v $(modver) --all
 
 .PHONY: all src_install build install uninstall

NEWS

@@ -1,3 +1,38 @@
+Version 0.8 - 5 December 2013
+
+* Compatibility with Linux 3.13.
+
+Version 0.7 - 28 May 2013
+
+* Fixes a scary WARNING on Linux 3.9.
+* Improved debug information when an ACPI method cannot be executed.
+* Added copyright information, update my name.
+
+Version 0.6 - 19 March 2013
+
+* Add workaround for Linux 3.8 regression (not present in earlier or latter
+  versions) that prevented the video card from turned off unless a driver was
+  loaded before.
+* Compatibility with grsec patches.
+* Add 'skip_optimus_dsm' module option so users of Lenovo T410s can use bbswitch
+  by setting this option to true.
+* Clarify license (GPLv3).
+
+Version 0.5 - 22 October 2012
+
+* Improved compatibility with older DKMS versions.
+* Set device state to D3cold instead of D3hot.
+* Only print DSM method call results when debugging is enabled.
+* Fixed runtime power management regression in Linux 3.6.
+
+Version 0.4.2 - 26 April 2012
+
+* Fixed a documentation error on unload_state.
+* Added Makefile.dkms and documentation for easier installation using DKMS.
+* Make /proc/acpi/bbswitch world-writable
+* Fix NULL pointer dereference when reporting a failure during ACPI method
+  evaluation.
+
 Version 0.4.1 - 16 January 2012
 
 * Corrected a small error that yielded an confusing error message "The discrete

README.md

@@ -22,6 +22,16 @@ detect the correct handle preceding _DSM and has some built-in safeguards:
   disabled again if that was the case before suspending. Hibernation should
   work, but it not tested.
 
+Precautionary measure : 
+- On some machines, turning off the card is permanent and the card does not
+  reappear on subsequents reboots, which can result into the screen staying
+  black all the time, including the BIOS screen.
+  If it occurs, first try to shutdown, unplug power cord, remove battery, wait
+  30s, then put everything back in and boot. If it's not solved, then the
+  solution is to reset the BIOS to factory settings. Before executing bbswitch
+  for the first time, it is therefore recommended to take note of the full key
+  sequence in the BIOS to do a reset. 
+
 Build
 -----
 
@@ -40,8 +50,8 @@ DKMS support
 
 If you have DKMS installed, you can install bbswitch in such a way that it
 survives kernel upgrades. It is recommended to remove older versions of bbswitch
-by running `dkms remove bbswitch/OLDVERSION --all` as root. To install the new
-version, simply run:
+by running `dkms remove -m bbswitch -v OLDVERSION --all` as root. To install
+the new version, simply run:
 
     # make -f Makefile.dkms
 
@@ -80,7 +90,7 @@ The module has some options that control the behavior on loading and unloading:
 `load_state` and `unload_state`. Valid values are `-1`, `0` and `1` meaning "do
 not change the card state", "turn the card off" and "turn the card on"
 respectively. For example, if you want to have `bbswitch` disable the card
-immediately when loading the module while disabling the card on unload, load the
+immediately when loading the module while enabling the card on unload, load the
 module with:
 
     # modprobe bbswitch load_state=0 unload_state=1
@@ -94,6 +104,10 @@ same behavior as:
 If not explictly set, the default behavior is not to change the power state of
 the discrete video card which equals to `load_state=-1 unload_state=-1`.
 
+The Lenovo T410 and Lenovo T410s laptops need the module option
+`skip_optimus_dsm=1`, otherwise it will detect the wrong methods which result in
+the card not being disabled.
+
 ### Disable card on boot
 
 These options can be useful to disable the card on boot time. Depending on your
@@ -103,10 +117,27 @@ get disabled on boot:
 
     bbswitch load_state=0
 
+Users of `kmod` should create `/etc/modprobe.d/bbswitch.conf` containing
+`options bbswitch load_state=0` to set the default options. To load the module,
+systemd users should create `/etc/modules-load.d/bbswitch.conf` containing
+`bbswitch`.
+
 You have to update your initial ramdisk (initrd) for the changes propagate to
 the boot process. On Debian and Ubuntu, this can performed by running
 `update-initramfs -u` as root.
 
+### Enable card on shutdown
+
+Some machines do not like the card being disabled at shutdown.  
+Add the next initscript (`/etc/init/bbswitch.conf`) :
+
+    description "Save power by disabling nvidia on Optimus"
+    author      "Lekensteyn <lekensteyn@gmail.com>"
+    start on    runlevel [2345]
+    stop on     runlevel [016]
+    pre-start   exec /sbin/modprobe bbswitch load_state=0 unload_state=1
+    pre-stop    exec /sbin/rmmod bbswitch 
+
 Reporting bugs
 --------------
 

bbswitch.c

@@ -9,18 +9,38 @@
  * Get status
  * # cat /proc/acpi/bbswitch
  */
+/*
+ *  Copyright (C) 2011-2013 Bumblebee Project
+ *  Author: Peter Wu <lekensteyn@gmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/pci.h>
 #include <linux/acpi.h>
 #include <linux/module.h>
 #include <asm/uaccess.h>
 #include <linux/suspend.h>
 #include <linux/seq_file.h>
+#include <linux/pm_runtime.h>
 
-#define BBSWITCH_VERSION "0.4.1"
+#define BBSWITCH_VERSION "0.8"
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Toggle the discrete graphics card");
-MODULE_AUTHOR("Peter Lekensteyn <lekensteyn@gmail.com>");
+MODULE_AUTHOR("Peter Wu <lekensteyn@gmail.com>");
 MODULE_VERSION(BBSWITCH_VERSION);
 
 enum {
@@ -35,6 +55,9 @@ module_param(load_state, int, 0400);
 static int unload_state = CARD_UNCHANGED;
 MODULE_PARM_DESC(unload_state, "Card state on unload (0 = off, 1 = on, -1 = unchanged)");
 module_param(unload_state, int, 0600);
+static bool skip_optimus_dsm = false;
+MODULE_PARM_DESC(skip_optimus_dsm, "Skip probe of Optimus discrete DSM (default = false)");
+module_param(skip_optimus_dsm, bool, 0400);
 
 extern struct proc_dir_entry *acpi_root_dir;
 
@@ -43,8 +66,6 @@ static const char acpi_optimus_dsm_muid[16] = {
     0xA7, 0x2B, 0x60, 0x42, 0xA6, 0xB5, 0xBE, 0xE0,
 };
 
-#define MXM_WMMX_GUID "F6CB5C3C-9CAE-4EBD-B577-931EA32A2CC0"
-#define MXM_WMMX_FUNC_DSM 0x4D53445F /* NVIDIA/Optimus DSM */
 static const char acpi_nvidia_dsm_muid[16] = {
     0xA0, 0xA0, 0x95, 0x9D, 0x60, 0x00, 0x48, 0x4D,
     0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4
@@ -60,43 +81,25 @@ It looks like something for Intel GPU:
 http://lxr.linux.no/#linux+v3.1.5/drivers/gpu/drm/i915/intel_acpi.c
  */
 
-struct mxdsm_args {
-    u32 func;
-    char muid[16];
-    u32 revid;
-    u32 sfnc;
-    char args[4];
-};
-
-enum dsm_type {
-    DSM_TYPE_UNSUPPORTED,
-    DSM_TYPE_OPTIMUS,
-    DSM_TYPE_NVIDIA,
-    /* _DSM call through a WMI MX method */
-    DSM_TYPE_OPTIMUS_WMI,
-    DSM_TYPE_NVIDIA_WMI,
-};
-static enum dsm_type dsm_type = DSM_TYPE_UNSUPPORTED;
+#define DSM_TYPE_UNSUPPORTED    0
+#define DSM_TYPE_OPTIMUS        1
+#define DSM_TYPE_NVIDIA         2
+static int dsm_type = DSM_TYPE_UNSUPPORTED;
 
 static struct pci_dev *dis_dev;
 static acpi_handle dis_handle;
 
-/* used for keeping the PM event handler */
-static struct notifier_block nb;
 /* whether the card was off before suspend or not; on: 0, off: 1 */
-int dis_before_suspend_disabled;
+static int dis_before_suspend_disabled;
 
-static char *buffer_to_string(const char buffer[], char *target) {
+static char *buffer_to_string(const char *buffer, size_t n, char *target) {
     int i;
-    for (i=0; i<sizeof(buffer); i++) {
-        sprintf(target + i * 5, "%02X,", buffer[i]);
+    for (i=0; i<n; i++) {
+        snprintf(target + i * 5, 5 * (n - i), "0x%02X,", buffer ? buffer[i] & 0xFF : 0);
     }
-    target[sizeof(buffer) * 5] = '\0';
     return target;
 }
 
-static int parse_dsm_result(struct acpi_buffer *output, uint32_t *result);
-
 // Returns 0 if the call succeeded and non-zero otherwise. If the call
 // succeeded, the result is stored in "result" providing that the result is an
 // integer or a buffer containing 4 values
@@ -105,6 +108,7 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
     struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
     struct acpi_object_list input;
     union acpi_object params[4];
+    union acpi_object *obj;
     int err;
 
     input.count = 4;
@@ -116,6 +120,9 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
     params[1].integer.value = revid;
     params[2].type = ACPI_TYPE_INTEGER;
     params[2].integer.value = func;
+    /* Although the ACPI spec defines Arg3 as a Package, in practise
+     * implementations expect a Buffer (CreateWordField and Index functions are
+     * applied to it). */
     params[3].type = ACPI_TYPE_BUFFER;
     params[3].buffer.length = 4;
     if (args) {
@@ -128,20 +135,20 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
 
     err = acpi_evaluate_object(handle, "_DSM", &input, &output);
     if (err) {
-        char tmp[5 * max(sizeof(muid), sizeof(args))];
+        struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
+        char muid_str[5 * 16];
+        char args_str[5 * 4];
+
+        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buf);
 
-        printk(KERN_WARNING "bbswitch: failed to evaluate _DSM {%s} %X %X"
-            " {%s}: %s\n",
-            buffer_to_string(muid, tmp), revid, func,
-            buffer_to_string(args, tmp), acpi_format_exception(err));
+        pr_warn("failed to evaluate %s._DSM {%s} 0x%X 0x%X {%s}: %s\n",
+            (char *)buf.pointer,
+            buffer_to_string(muid, 16, muid_str), revid, func,
+            buffer_to_string(args,  4, args_str), acpi_format_exception(err));
         return err;
     }
-    return parse_dsm_result(&output, result);
-}
 
-// Processes the result of an ACPI _DSM call and deallocates the result memory
-static int parse_dsm_result(struct acpi_buffer *output, uint32_t *result) {
-    union acpi_object *obj = output->pointer;
+    obj = (union acpi_object *)output.pointer;
 
     if (obj->type == ACPI_TYPE_INTEGER && result) {
         *result = obj->integer.value;
@@ -154,11 +161,11 @@ static int parse_dsm_result(struct acpi_buffer *output, uint32_t *result) {
             *result |= (obj->buffer.pointer[3] << 24);
         }
     } else {
-        printk(KERN_WARNING "bbswitch: _DSM call yields an unsupported result"
-            " type: %X\n", obj->type);
+        pr_warn("_DSM call yields an unsupported result type: %#x\n",
+            obj->type);
     }
 
-    kfree(output->pointer);
+    kfree(output.pointer);
     return 0;
 }
 
@@ -175,113 +182,47 @@ static int has_dsm_func(const char muid[16], int revid, int sfnc) {
     return result & 1 && result & (1 << sfnc);
 }
 
-// Returns 0 if the call succeeded and non-zero otherwise. If the call
-// succeeded, the result is stored in "result" providing that the result is an
-// integer or a buffer containing 4 values
-static int wmmx_call(const char muid[16], int revid, int func, char args[4],
-    uint32_t *result) {
-    struct mxdsm_args mx_args = {
-        .func = MXM_WMMX_FUNC_DSM,
-        .revid = revid,
-        .sfnc = func,
-    };
-    struct acpi_buffer input = { (acpi_size)sizeof(mx_args), &mx_args };
-    struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-    acpi_status status;
-
-    memcpy(mx_args.muid, muid, sizeof(mx_args.muid));
-    if (args) {
-        memcpy(mx_args.args, args, sizeof(mx_args.args));
-    } else {
-        // some implementations do not like empty values
-        memset(mx_args.args, 0, sizeof(mx_args.args));
-    }
-
-    // 1, > 1 <-- required by at least Acer Travelmate 8472TG, seen on others
-    status = wmi_evaluate_method(MXM_WMMX_GUID, 1, 1, &input, &output);
-    if (ACPI_FAILURE(status)) {
-        printk(KERN_WARNING "bbswitch: failed to evaluate WMMX: %s\n",
-            acpi_format_exception(status));
-        return status;
-    }
-    return parse_dsm_result(&output, result);
-}
-
-// Returns 1 if a _DSM function and its function index exists and 0 otherwise
-static int has_wmi_func(const char muid[16], int revid, int sfnc) {
-    u32 result = 0;
-
-    // fail if the _DSM call failed
-    if (wmmx_call(muid, revid, 0, 0, &result))
-        return 0;
-
-    // ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported. If
-    // the n-th bit is enabled, function n is supported
-    return result & 1 && result & (1 << sfnc);
-}
-
 static int bbswitch_optimus_dsm(void) {
+    if (dsm_type == DSM_TYPE_OPTIMUS) {
         char args[] = {1, 0, 0, 3};
         u32 result = 0;
-    if (dsm_type == DSM_TYPE_OPTIMUS) {
+
         if (acpi_call_dsm(dis_handle, acpi_optimus_dsm_muid, 0x100, 0x1A, args,
             &result)) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of Optimus _DSM call: %08X\n",
-            result);
-    } else if (dsm_type == DSM_TYPE_OPTIMUS_WMI) {
-        if (wmmx_call(acpi_optimus_dsm_muid, 0x100, 0x1A, args, &result)) {
-            // failure
-            return 1;
-        }
-        printk(KERN_DEBUG "bbswitch: Result of WMMX call for Optimus: %08X\n",
-            result);
+        pr_debug("Result of Optimus _DSM call: %08X\n", result);
     }
     return 0;
 }
 
 static int bbswitch_acpi_off(void) {
+    if (dsm_type == DSM_TYPE_NVIDIA) {
         char args[] = {2, 0, 0, 0};
         u32 result = 0;
-    if (dsm_type == DSM_TYPE_NVIDIA) {
+
         if (acpi_call_dsm(dis_handle, acpi_nvidia_dsm_muid, 0x102, 0x3, args,
             &result)) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of _DSM call for OFF: %08X\n",
-            result);
-    } else if (dsm_type == DSM_TYPE_NVIDIA_WMI) {
-        if (wmmx_call(acpi_nvidia_dsm_muid, 0x102, 0x3, args, &result)) {
-            // failure
-            return 1;
-        }
-        printk(KERN_DEBUG "bbswitch: Result of WMMX call for OFF: %08X\n",
-            result);
+        pr_debug("Result of _DSM call for OFF: %08X\n", result);
     }
     return 0;
 }
 
 static int bbswitch_acpi_on(void) {
+    if (dsm_type == DSM_TYPE_NVIDIA) {
         char args[] = {1, 0, 0, 0};
         u32 result = 0;
-    if (dsm_type == DSM_TYPE_NVIDIA) {
+
         if (acpi_call_dsm(dis_handle, acpi_nvidia_dsm_muid, 0x102, 0x3, args,
             &result)) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of _DSM call for ON: %08X\n",
-            result);
-    } else if (dsm_type == DSM_TYPE_NVIDIA_WMI) {
-        if (wmmx_call(acpi_nvidia_dsm_muid, 0x102, 0x3, args, &result)) {
-            // failure
-            return 1;
-        }
-        printk(KERN_DEBUG "bbswitch: Result of WMMX call for ON: %08X\n",
-            result);
+        pr_debug("Result of _DSM call for ON: %08X\n", result);
     }
     return 0;
 }
@@ -304,47 +245,68 @@ static void bbswitch_off(void) {
     // to prevent the system from possibly locking up, don't disable the device
     // if it's still in use by a driver (i.e. nouveau or nvidia)
     if (dis_dev->driver) {
-        printk(KERN_WARNING "bbswitch: device %s is in use by driver '%s', "
-            "refusing OFF\n", dev_name(&dis_dev->dev), dis_dev->driver->name);
+        pr_warn("device %s is in use by driver '%s', refusing OFF\n",
+            dev_name(&dis_dev->dev), dis_dev->driver->name);
         return;
     }
 
-    printk(KERN_INFO "bbswitch: disabling discrete graphics\n");
+    pr_info("disabling discrete graphics\n");
 
     if (bbswitch_optimus_dsm()) {
-        printk(KERN_WARNING "bbswitch: Optimus ACPI call failed, the device is"
-            " not disabled\n");
+        pr_warn("Optimus ACPI call failed, the device is not disabled\n");
         return;
     }
 
     pci_save_state(dis_dev);
     pci_clear_master(dis_dev);
     pci_disable_device(dis_dev);
-    pci_set_power_state(dis_dev, PCI_D3hot);
+    do {
+        struct acpi_device *ad = NULL;
+        int r;
+
+        r = acpi_bus_get_device(dis_handle, &ad);
+        if (r || !ad) {
+            pr_warn("Cannot get ACPI device for PCI device\n");
+            break;
+        }
+        if (ad->power.state == ACPI_STATE_UNKNOWN) {
+            pr_debug("ACPI power state is unknown, forcing D0\n");
+            ad->power.state = ACPI_STATE_D0;
+        }
+    } while (0);
+    pci_set_power_state(dis_dev, PCI_D3cold);
 
     if (bbswitch_acpi_off())
-        printk(KERN_WARNING "bbswitch: The discrete card could not be disabled"
-                " by a _DSM call\n");
+        pr_warn("The discrete card could not be disabled by a _DSM call\n");
 }
 
 static void bbswitch_on(void) {
     if (!is_card_disabled())
         return;
 
-    printk(KERN_INFO "bbswitch: enabling discrete graphics\n");
+    pr_info("enabling discrete graphics\n");
 
     if (bbswitch_acpi_on())
-        printk(KERN_WARNING "bbswitch: The discrete card could not be enabled"
-            " by a _DSM call\n");
+        pr_warn("The discrete card could not be enabled by a _DSM call\n");
 
     pci_set_power_state(dis_dev, PCI_D0);
     pci_restore_state(dis_dev);
     if (pci_enable_device(dis_dev))
-        printk(KERN_WARNING "bbswitch: failed to enable %s\n",
-            dev_name(&dis_dev->dev));
+        pr_warn("failed to enable %s\n", dev_name(&dis_dev->dev));
     pci_set_master(dis_dev);
 }
 
+/* power bus so we can read PCI configuration space */
+static void dis_dev_get(void) {
+    if (dis_dev->bus && dis_dev->bus->self)
+        pm_runtime_get_sync(&dis_dev->bus->self->dev);
+}
+
+static void dis_dev_put(void) {
+    if (dis_dev->bus && dis_dev->bus->self)
+        pm_runtime_put_sync(&dis_dev->bus->self->dev);
+}
+
 static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
     size_t len, loff_t *off) {
     char cmd[8];
@@ -355,19 +317,25 @@ static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
     if (copy_from_user(cmd, buff, len))
         return -EFAULT;
 
+    dis_dev_get();
+
     if (strncmp(cmd, "OFF", 3) == 0)
         bbswitch_off();
 
     if (strncmp(cmd, "ON", 2) == 0)
         bbswitch_on();
 
+    dis_dev_put();
+
     return len;
 }
 
 static int bbswitch_proc_show(struct seq_file *seqfp, void *p) {
     // show the card state. Example output: 0000:01:00:00 ON
+    dis_dev_get();
     seq_printf(seqfp, "%s %s\n", dev_name(&dis_dev->dev),
              is_card_disabled() ? "OFF" : "ON");
+    dis_dev_put();
     return 0;
 }
 static int bbswitch_proc_open(struct inode *inode, struct file *file) {
@@ -379,19 +347,24 @@ static int bbswitch_pm_handler(struct notifier_block *nbp,
     switch (event_type) {
     case PM_HIBERNATION_PREPARE:
     case PM_SUSPEND_PREPARE:
+        dis_dev_get();
         dis_before_suspend_disabled = is_card_disabled();
         // enable the device before suspend to avoid the PCI config space from
         // being saved incorrectly
         if (dis_before_suspend_disabled)
             bbswitch_on();
+        dis_dev_put();
         break;
     case PM_POST_HIBERNATION:
     case PM_POST_SUSPEND:
     case PM_POST_RESTORE:
         // after suspend, the card is on, but if it was off before suspend,
         // disable it again
-        if (dis_before_suspend_disabled)
+        if (dis_before_suspend_disabled) {
+            dis_dev_get();
             bbswitch_off();
+            dis_dev_put();
+        }
         break;
     case PM_RESTORE_PREPARE:
         // deliberately don't do anything as it does not occur before suspend
@@ -410,12 +383,16 @@ static struct file_operations bbswitch_fops = {
     .release= single_release
 };
 
+static struct notifier_block nb = {
+    .notifier_call = &bbswitch_pm_handler
+};
+
 static int __init bbswitch_init(void) {
     struct proc_dir_entry *acpi_entry;
     struct pci_dev *pdev = NULL;
     acpi_handle igd_handle = NULL;
 
-    printk(KERN_INFO "bbswitch: version %s\n", BBSWITCH_VERSION);
+    pr_info("version %s\n", BBSWITCH_VERSION);
 
     while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev)) != NULL) {
         struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -426,10 +403,16 @@ static int __init bbswitch_init(void) {
             pci_class != PCI_CLASS_DISPLAY_3D)
             continue;
 
+#ifdef ACPI_HANDLE
+        /* since Linux 3.8 */
+        handle = ACPI_HANDLE(&pdev->dev);
+#else
+        /* removed since Linux 3.13 */
         handle = DEVICE_ACPI_HANDLE(&pdev->dev);
+#endif
         if (!handle) {
-            printk(KERN_WARNING "bbswitch: cannot find ACPI handle for VGA"
-                " device %s\n", dev_name(&pdev->dev));
+            pr_warn("cannot find ACPI handle for VGA device %s\n",
+                dev_name(&pdev->dev));
             continue;
         }
 
@@ -437,67 +420,67 @@ static int __init bbswitch_init(void) {
 
         if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
             igd_handle = handle;
-            printk(KERN_INFO "bbswitch: Found integrated VGA device %s: %s\n",
+            pr_info("Found integrated VGA device %s: %s\n",
                 dev_name(&pdev->dev), (char *)buf.pointer);
         } else {
             dis_dev = pdev;
             dis_handle = handle;
-            printk(KERN_INFO "bbswitch: Found discrete VGA device %s: %s\n",
+            pr_info("Found discrete VGA device %s: %s\n",
                 dev_name(&pdev->dev), (char *)buf.pointer);
         }
         kfree(buf.pointer);
     }
 
     if (dis_dev == NULL) {
-        printk(KERN_ERR "bbswitch: No discrete VGA device found\n");
+        pr_err("No discrete VGA device found\n");
         return -ENODEV;
     }
 
-    if (has_wmi_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
-        dsm_type = DSM_TYPE_OPTIMUS_WMI;
-        printk(KERN_INFO "bbswitch: detected an Optimus WMMX function\n");
-    } else if (has_wmi_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
-        dsm_type = DSM_TYPE_NVIDIA_WMI;
-        printk(KERN_INFO "bbswitch: detected a nVidia WMMX function\n");
-    } else if (has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
-        /* necessary for at least Lenovo Ideapad Z570 which does not have the
-         * WMMX method */
+    if (!skip_optimus_dsm &&
+            has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
         dsm_type = DSM_TYPE_OPTIMUS;
-        printk(KERN_INFO "bbswitch: detected an Optimus _DSM function\n");
+        pr_info("detected an Optimus _DSM function\n");
     } else if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
-        /* necessary for at least Dell XPS L501X bios A08 which does not have
-         * the WMMX method */
         dsm_type = DSM_TYPE_NVIDIA;
-        printk(KERN_INFO "bbswitch: detected a nVidia _DSM function\n");
+        pr_info("detected a nVidia _DSM function\n");
     } else {
        /* At least two Acer machines are known to use the intel ACPI handle
         * with the legacy nvidia DSM */
         dis_handle = igd_handle;
-        if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
+        if (dis_handle && has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
             dsm_type = DSM_TYPE_NVIDIA;
-            printk(KERN_INFO "bbswitch: detected a nVidia _DSM function on the"
+            pr_info("detected a nVidia _DSM function on the"
                 " integrated video card\n");
         } else {
-            printk(KERN_ERR "bbswitch: No suitable _DSM call found.\n");
+            pr_err("No suitable _DSM call found.\n");
             return -ENODEV;
         }
     }
 
     acpi_entry = proc_create("bbswitch", 0664, acpi_root_dir, &bbswitch_fops);
     if (acpi_entry == NULL) {
-        printk(KERN_ERR "bbswitch: Couldn't create proc entry\n");
+        pr_err("Couldn't create proc entry\n");
         return -ENOMEM;
     }
 
+    dis_dev_get();
+
+    if (!is_card_disabled()) {
+        /* We think the card is enabled, so ensure the kernel does as well */
+        if (pci_enable_device(dis_dev))
+            pr_warn("failed to enable %s\n", dev_name(&dis_dev->dev));
+    }
+
     if (load_state == CARD_ON)
         bbswitch_on();
     else if (load_state == CARD_OFF)
         bbswitch_off();
 
-    printk(KERN_INFO "bbswitch: Succesfully loaded. Discrete card %s is %s\n",
+    pr_info("Succesfully loaded. Discrete card %s is %s\n",
         dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
 
-    nb.notifier_call = &bbswitch_pm_handler;
+    dis_dev_put();
+
     register_pm_notifier(&nb);
 
     return 0;
@@ -506,17 +489,23 @@ static int __init bbswitch_init(void) {
 static void __exit bbswitch_exit(void) {
     remove_proc_entry("bbswitch", acpi_root_dir);
 
+    dis_dev_get();
+
     if (unload_state == CARD_ON)
         bbswitch_on();
     else if (unload_state == CARD_OFF)
         bbswitch_off();
 
-    printk(KERN_INFO "bbswitch: Unloaded. Discrete card %s is %s\n",
+    pr_info("Unloaded. Discrete card %s is %s\n",
         dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
 
+    dis_dev_put();
+
     if (nb.notifier_call)
         unregister_pm_notifier(&nb);
 }
 
 module_init(bbswitch_init);
 module_exit(bbswitch_exit);
+
+/* vim: set sw=4 ts=4 et: */