Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux

Pull drm updates from Dave Airlie:
 "Okay this is the big one, I was stalled on the fbdev pull req as I
  stupidly let fbdev guys merge a patch I required to fix a warning with
  some patches I had, they ended up merging the patch from the wrong
  place, but the warning should be fixed.  In future I'll just take the
  patch myself!

  Outside drm:

  There are some snd changes for the HDMI audio interactions on haswell,
  they've been acked for inclusion via my tree.  This relies on the
  wound/wait tree from Ingo which is already merged.

  Major changes:

  AMD finally released the dynamic power management code for all their
  GPUs from r600->present day, this is great, off by default for now but
  also a huge amount of code, in fact it is most of this pull request.

  Since it landed there has been a lot of community testing and Alex has
  sent a lot of fixes for any bugs found so far.  I suspect radeon might
  now be the biggest kernel driver ever :-P p.s.  radeon.dpm=1 to enable
  dynamic powermanagement for anyone.

  New drivers:

  Renesas r-car display unit.

  Other highlights:

   - core: GEM CMA prime support, use new w/w mutexs for TTM
     reservations, cursor hotspot, doc updates
   - dvo chips: chrontel 7010B support
   - i915: Haswell (fbc, ips, vecs, watermarks, audio powerwell),
     Valleyview (enabled by default, rc6), lots of pll reworking, 30bpp
     support (this time for sure)
   - nouveau: async buffer object deletion, context/register init
     updates, kernel vp2 engine support, GF117 support, GK110 accel
     support (with external nvidia ucode), context cleanups.
   - exynos: memory leak fixes, Add S3C64XX SoC series support, device
     tree updates, common clock framework support,
   - qxl: cursor hotspot support, multi-monitor support, suspend/resume
     support
   - mgag200: hw cursor support, g200 mode limiting
   - shmobile: prime support
   - tegra: fixes mostly

  I've been banging on this quite a lot due to the size of it, and it
  seems to okay on everything I've tested it on."

* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (811 commits)
  drm/radeon/dpm: implement vblank_too_short callback for si
  drm/radeon/dpm: implement vblank_too_short callback for cayman
  drm/radeon/dpm: implement vblank_too_short callback for btc
  drm/radeon/dpm: implement vblank_too_short callback for evergreen
  drm/radeon/dpm: implement vblank_too_short callback for 7xx
  drm/radeon/dpm: add checks against vblank time
  drm/radeon/dpm: add helper to calculate vblank time
  drm/radeon: remove stray line in old pm code
  drm/radeon/dpm: fix display_gap programming on rv7xx
  drm/nvc0/gr: fix gpc firmware regression
  drm/nouveau: fix minor thinko causing bo moves to not be async on kepler
  drm/radeon/dpm: implement force performance level for TN
  drm/radeon/dpm: implement force performance level for ON/LN
  drm/radeon/dpm: implement force performance level for SI
  drm/radeon/dpm: implement force performance level for cayman
  drm/radeon/dpm: implement force performance levels for 7xx/eg/btc
  drm/radeon/dpm: add infrastructure to force performance levels
  drm/radeon: fix surface setup on r1xx
  drm/radeon: add support for 3d perf states on older asics
  drm/radeon: set default clocks for SI when DPM is disabled
  ...

9 files changed, 259 insertions, 75 deletions

diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index fca34192cf80..cbfdf5486639 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -126,6 +126,8 @@ X!Edrivers/base/interface.c
      </sect1>
      <sect1><title>Device Drivers DMA Management</title>
 !Edrivers/base/dma-buf.c
+!Edrivers/base/reservation.c
+!Iinclude/linux/reservation.h
 !Edrivers/base/dma-coherent.c
 !Edrivers/base/dma-mapping.c
      </sect1>
diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index 6dd8d10d6b7e..7d1278e7a434 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -186,11 +186,12 @@
           <varlistentry>
             <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
             <listitem><para>
-              DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler. The
-              DRM core will automatically register an interrupt handler when the
-              flag is set. DRIVER_IRQ_SHARED indicates whether the device &amp;
-              handler support shared IRQs (note that this is required of PCI
-              drivers).
+              DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler
+              managed by the DRM Core. The core will support simple IRQ handler
+              installation when the flag is set. The installation process is
+              described in <xref linkend="drm-irq-registration"/>.</para>
+              <para>DRIVER_IRQ_SHARED indicates whether the device &amp; handler
+              support shared IRQs (note that this is required of PCI  drivers).
             </para></listitem>
           </varlistentry>
           <varlistentry>
@@ -344,50 +345,71 @@ char *date;</synopsis>
           The DRM core tries to facilitate IRQ handler registration and
           unregistration by providing <function>drm_irq_install</function> and
           <function>drm_irq_uninstall</function> functions. Those functions only
-          support a single interrupt per device.
-        </para>
-  <!--!Fdrivers/char/drm/drm_irq.c drm_irq_install-->
-        <para>
-          Both functions get the device IRQ by calling
-          <function>drm_dev_to_irq</function>. This inline function will call a
-          bus-specific operation to retrieve the IRQ number. For platform devices,
-          <function>platform_get_irq</function>(..., 0) is used to retrieve the
-          IRQ number.
-        </para>
-        <para>
-          <function>drm_irq_install</function> starts by calling the
-          <methodname>irq_preinstall</methodname> driver operation. The operation
-          is optional and must make sure that the interrupt will not get fired by
-          clearing all pending interrupt flags or disabling the interrupt.
-        </para>
-        <para>
-          The IRQ will then be requested by a call to
-          <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver
-          feature flag is set, a shared (IRQF_SHARED) IRQ handler will be
-          requested.
-        </para>
-        <para>
-          The IRQ handler function must be provided as the mandatory irq_handler
-          driver operation. It will get passed directly to
-          <function>request_irq</function> and thus has the same prototype as all
-          IRQ handlers. It will get called with a pointer to the DRM device as the
-          second argument.
-        </para>
-        <para>
-          Finally the function calls the optional
-          <methodname>irq_postinstall</methodname> driver operation. The operation
-          usually enables interrupts (excluding the vblank interrupt, which is
-          enabled separately), but drivers may choose to enable/disable interrupts
-          at a different time.
-        </para>
-        <para>
-          <function>drm_irq_uninstall</function> is similarly used to uninstall an
-          IRQ handler. It starts by waking up all processes waiting on a vblank
-          interrupt to make sure they don't hang, and then calls the optional
-          <methodname>irq_uninstall</methodname> driver operation. The operation
-          must disable all hardware interrupts. Finally the function frees the IRQ
-          by calling <function>free_irq</function>.
+          support a single interrupt per device, devices that use more than one
+          IRQs need to be handled manually.
         </para>
+        <sect4>
+          <title>Managed IRQ Registration</title>
+          <para>
+            Both the <function>drm_irq_install</function> and
+	    <function>drm_irq_uninstall</function> functions get the device IRQ by
+	    calling <function>drm_dev_to_irq</function>. This inline function will
+	    call a bus-specific operation to retrieve the IRQ number. For platform
+	    devices, <function>platform_get_irq</function>(..., 0) is used to
+	    retrieve the IRQ number.
+          </para>
+          <para>
+            <function>drm_irq_install</function> starts by calling the
+            <methodname>irq_preinstall</methodname> driver operation. The operation
+            is optional and must make sure that the interrupt will not get fired by
+            clearing all pending interrupt flags or disabling the interrupt.
+          </para>
+          <para>
+            The IRQ will then be requested by a call to
+            <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver
+            feature flag is set, a shared (IRQF_SHARED) IRQ handler will be
+            requested.
+          </para>
+          <para>
+            The IRQ handler function must be provided as the mandatory irq_handler
+            driver operation. It will get passed directly to
+            <function>request_irq</function> and thus has the same prototype as all
+            IRQ handlers. It will get called with a pointer to the DRM device as the
+            second argument.
+          </para>
+          <para>
+            Finally the function calls the optional
+            <methodname>irq_postinstall</methodname> driver operation. The operation
+            usually enables interrupts (excluding the vblank interrupt, which is
+            enabled separately), but drivers may choose to enable/disable interrupts
+            at a different time.
+          </para>
+          <para>
+            <function>drm_irq_uninstall</function> is similarly used to uninstall an
+            IRQ handler. It starts by waking up all processes waiting on a vblank
+            interrupt to make sure they don't hang, and then calls the optional
+            <methodname>irq_uninstall</methodname> driver operation. The operation
+            must disable all hardware interrupts. Finally the function frees the IRQ
+            by calling <function>free_irq</function>.
+          </para>
+        </sect4>
+        <sect4>
+          <title>Manual IRQ Registration</title>
+          <para>
+            Drivers that require multiple interrupt handlers can't use the managed
+            IRQ registration functions. In that case IRQs must be registered and
+            unregistered manually (usually with the <function>request_irq</function>
+            and <function>free_irq</function> functions, or their devm_* equivalent).
+          </para>
+          <para>
+            When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ
+            driver feature flag, and must not provide the
+	    <methodname>irq_handler</methodname> driver operation. They must set the
+	    <structname>drm_device</structname> <structfield>irq_enabled</structfield>
+	    field to 1 upon registration of the IRQs, and clear it to 0 after
+	    unregistering the IRQs.
+          </para>
+        </sect4>
       </sect3>
       <sect3>
         <title>Memory Manager Initialization</title>
@@ -1214,6 +1236,15 @@ int max_width, max_height;</synopsis>
           <title>Miscellaneous</title>
           <itemizedlist>
             <listitem>
+              <synopsis>void (*set_property)(struct drm_crtc *crtc,
+                     struct drm_property *property, uint64_t value);</synopsis>
+              <para>
+                Set the value of the given CRTC property to
+                <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
+                for more information about properties.
+              </para>
+            </listitem>
+            <listitem>
               <synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
                         uint32_t start, uint32_t size);</synopsis>
               <para>
@@ -1363,6 +1394,15 @@ int max_width, max_height;</synopsis>
               <xref linkend="drm-kms-init"/>.
             </para>
           </listitem>
+          <listitem>
+            <synopsis>void (*set_property)(struct drm_plane *plane,
+                     struct drm_property *property, uint64_t value);</synopsis>
+            <para>
+              Set the value of the given plane property to
+              <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
+              for more information about properties.
+            </para>
+          </listitem>
         </itemizedlist>
       </sect3>
     </sect2>
@@ -1572,6 +1612,15 @@ int max_width, max_height;</synopsis>
           <title>Miscellaneous</title>
           <itemizedlist>
             <listitem>
+              <synopsis>void (*set_property)(struct drm_connector *connector,
+                     struct drm_property *property, uint64_t value);</synopsis>
+              <para>
+                Set the value of the given connector property to
+                <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
+                for more information about properties.
+              </para>
+            </listitem>
+            <listitem>
               <synopsis>void (*destroy)(struct drm_connector *connector);</synopsis>
               <para>
                 Destroy the connector when not needed anymore. See
@@ -1846,10 +1895,6 @@ void intel_crt_init(struct drm_device *dev)
           <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder,
                        const struct drm_display_mode *mode,
                        struct drm_display_mode *adjusted_mode);</synopsis>
-          <note><para>
-            FIXME: The mode argument be const, but the i915 driver modifies
-            mode-&gt;clock in <function>intel_dp_mode_fixup</function>.
-          </para></note>
           <para>
             Let encoders adjust the requested mode or reject it completely. This
             operation returns true if the mode is accepted (possibly after being
@@ -2161,6 +2206,128 @@ void intel_crt_init(struct drm_device *dev)
       <title>EDID Helper Functions Reference</title>
 !Edrivers/gpu/drm/drm_edid.c
     </sect2>
+    <sect2>
+      <title>Rectangle Utilities Reference</title>
+!Pinclude/drm/drm_rect.h rect utils
+!Iinclude/drm/drm_rect.h
+!Edrivers/gpu/drm/drm_rect.c
+    </sect2>
+  </sect1>
+
+  <!-- Internals: kms properties -->
+
+  <sect1 id="drm-kms-properties">
+    <title>KMS Properties</title>
+    <para>
+      Drivers may need to expose additional parameters to applications than
+      those described in the previous sections. KMS supports attaching
+      properties to CRTCs, connectors and planes and offers a userspace API to
+      list, get and set the property values.
+    </para>
+    <para>
+      Properties are identified by a name that uniquely defines the property
+      purpose, and store an associated value. For all property types except blob
+      properties the value is a 64-bit unsigned integer.
+    </para>
+    <para>
+      KMS differentiates between properties and property instances. Drivers
+      first create properties and then create and associate individual instances
+      of those properties to objects. A property can be instantiated multiple
+      times and associated with different objects. Values are stored in property
+      instances, and all other property information are stored in the propery
+      and shared between all instances of the property.
+    </para>
+    <para>
+      Every property is created with a type that influences how the KMS core
+      handles the property. Supported property types are
+      <variablelist>
+        <varlistentry>
+          <term>DRM_MODE_PROP_RANGE</term>
+          <listitem><para>Range properties report their minimum and maximum
+            admissible values. The KMS core verifies that values set by
+            application fit in that range.</para></listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>DRM_MODE_PROP_ENUM</term>
+          <listitem><para>Enumerated properties take a numerical value that
+            ranges from 0 to the number of enumerated values defined by the
+            property minus one, and associate a free-formed string name to each
+            value. Applications can retrieve the list of defined value-name pairs
+            and use the numerical value to get and set property instance values.
+            </para></listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>DRM_MODE_PROP_BITMASK</term>
+          <listitem><para>Bitmask properties are enumeration properties that
+            additionally restrict all enumerated values to the 0..63 range.
+            Bitmask property instance values combine one or more of the
+            enumerated bits defined by the property.</para></listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>DRM_MODE_PROP_BLOB</term>
+          <listitem><para>Blob properties store a binary blob without any format
+            restriction. The binary blobs are created as KMS standalone objects,
+            and blob property instance values store the ID of their associated
+            blob object.</para>
+	    <para>Blob properties are only used for the connector EDID property
+	    and cannot be created by drivers.</para></listitem>
+        </varlistentry>
+      </variablelist>
+    </para>
+    <para>
+      To create a property drivers call one of the following functions depending
+      on the property type. All property creation functions take property flags
+      and name, as well as type-specific arguments.
+      <itemizedlist>
+        <listitem>
+          <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags,
+                                               const char *name,
+                                               uint64_t min, uint64_t max);</synopsis>
+          <para>Create a range property with the given minimum and maximum
+            values.</para>
+        </listitem>
+        <listitem>
+          <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags,
+                                              const char *name,
+                                              const struct drm_prop_enum_list *props,
+                                              int num_values);</synopsis>
+          <para>Create an enumerated property. The <parameter>props</parameter>
+            argument points to an array of <parameter>num_values</parameter>
+            value-name pairs.</para>
+        </listitem>
+        <listitem>
+          <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev,
+                                                 int flags, const char *name,
+                                                 const struct drm_prop_enum_list *props,
+                                                 int num_values);</synopsis>
+          <para>Create a bitmask property. The <parameter>props</parameter>
+            argument points to an array of <parameter>num_values</parameter>
+            value-name pairs.</para>
+        </listitem>
+      </itemizedlist>
+    </para>
+    <para>
+      Properties can additionally be created as immutable, in which case they
+      will be read-only for applications but can be modified by the driver. To
+      create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE
+      flag at property creation time.
+    </para>
+    <para>
+      When no array of value-name pairs is readily available at property
+      creation time for enumerated or range properties, drivers can create
+      the property using the <function>drm_property_create</function> function
+      and manually add enumeration value-name pairs by calling the
+      <function>drm_property_add_enum</function> function. Care must be taken to
+      properly specify the property type through the <parameter>flags</parameter>
+      argument.
+    </para>
+    <para>
+      After creating properties drivers can attach property instances to CRTC,
+      connector and plane objects by calling the
+      <function>drm_object_attach_property</function>. The function takes a
+      pointer to the target object, a pointer to the previously created property
+      and an initial instance value.
+    </para>
   </sect1>
 
   <!-- Internals: vertical blanking -->
diff --git a/Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt b/Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt
index e5f130159ae1..fff10da5e927 100644
--- a/Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt
+++ b/Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt
@@ -10,6 +10,14 @@ Recommended properties:
    services interrupts for this device.
  - ti,hwmods: Name of the hwmod associated to the LCDC
 
+Optional properties:
+ - max-bandwidth: The maximum pixels per second that the memory
+   interface / lcd controller combination can sustain
+ - max-width: The maximum horizontal pixel width supported by
+   the lcd controller.
+ - max-pixelclock: The maximum pixel clock that can be supported
+   by the lcd controller in KHz.
+
 Example:
 
 	fb: fb@4830e000 {
diff --git a/Documentation/devicetree/bindings/video/display-timing.txt b/Documentation/devicetree/bindings/video/display-timing.txt
index 150038552bc3..e1d4a0b59612 100644
--- a/Documentation/devicetree/bindings/video/display-timing.txt
+++ b/Documentation/devicetree/bindings/video/display-timing.txt
@@ -34,6 +34,7 @@ optional properties:
 			- ignored     = ignored
  - interlaced (bool): boolean to enable interlaced mode
  - doublescan (bool): boolean to enable doublescan mode
+ - doubleclk (bool): boolean to enable doubleclock mode
 
 All the optional properties that are not bool follow the following logic:
     <1>: high active
diff --git a/Documentation/devicetree/bindings/video/exynos_hdmi.txt b/Documentation/devicetree/bindings/video/exynos_hdmi.txt
index 589edee37394..323983be3c30 100644
--- a/Documentation/devicetree/bindings/video/exynos_hdmi.txt
+++ b/Documentation/devicetree/bindings/video/exynos_hdmi.txt
@@ -1,22 +1,23 @@
 Device-Tree bindings for drm hdmi driver
 
 Required properties:
-- compatible: value should be "samsung,exynos5-hdmi".
+- compatible: value should be one among the following:
+	1) "samsung,exynos5-hdmi" <DEPRECATED>
+	2) "samsung,exynos4210-hdmi"
+	3) "samsung,exynos4212-hdmi"
 - reg: physical base address of the hdmi and length of memory mapped
 	region.
 - interrupts: interrupt number to the cpu.
 - hpd-gpio: following information about the hotplug gpio pin.
 	a) phandle of the gpio controller node.
 	b) pin number within the gpio controller.
-	c) pin function mode.
-	d) optional flags and pull up/down.
-	e) drive strength.
+	c) optional flags and pull up/down.
 
 Example:
 
 	hdmi {
-		compatible = "samsung,exynos5-hdmi";
+		compatible = "samsung,exynos4212-hdmi";
 		reg = <0x14530000 0x100000>;
 		interrupts = <0 95 0>;
-		hpd-gpio = <&gpx3 7 0xf 1 3>;
+		hpd-gpio = <&gpx3 7 1>;
 	};
diff --git a/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt b/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt
index fa166d945809..41eee971562b 100644
--- a/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt
+++ b/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt
@@ -1,12 +1,15 @@
 Device-Tree bindings for hdmiddc driver
 
 Required properties:
-- compatible: value should be "samsung,exynos5-hdmiddc".
+- compatible: value should be one of the following
+	1) "samsung,exynos5-hdmiddc" <DEPRECATED>
+	2) "samsung,exynos4210-hdmiddc"
+
 - reg: I2C address of the hdmiddc device.
 
 Example:
 
 	hdmiddc {
-		compatible = "samsung,exynos5-hdmiddc";
+		compatible = "samsung,exynos4210-hdmiddc";
 		reg = <0x50>;
 	};
diff --git a/Documentation/devicetree/bindings/video/exynos_hdmiphy.txt b/Documentation/devicetree/bindings/video/exynos_hdmiphy.txt
index 858f4f9b902f..162f641f7639 100644
--- a/Documentation/devicetree/bindings/video/exynos_hdmiphy.txt
+++ b/Documentation/devicetree/bindings/video/exynos_hdmiphy.txt
@@ -1,12 +1,15 @@
 Device-Tree bindings for hdmiphy driver
 
 Required properties:
-- compatible: value should be "samsung,exynos5-hdmiphy".
+- compatible: value should be one of the following:
+	1) "samsung,exynos5-hdmiphy" <DEPRECATED>
+	2) "samsung,exynos4210-hdmiphy".
+	3) "samsung,exynos4212-hdmiphy".
 - reg: I2C address of the hdmiphy device.
 
 Example:
 
 	hdmiphy {
-		compatible = "samsung,exynos5-hdmiphy";
+		compatible = "samsung,exynos4210-hdmiphy";
 		reg = <0x38>;
 	};
diff --git a/Documentation/devicetree/bindings/video/exynos_mixer.txt b/Documentation/devicetree/bindings/video/exynos_mixer.txt
index 9b2ea0343566..3334b0a8e343 100644
--- a/Documentation/devicetree/bindings/video/exynos_mixer.txt
+++ b/Documentation/devicetree/bindings/video/exynos_mixer.txt
@@ -1,7 +1,12 @@
 Device-Tree bindings for mixer driver
 
 Required properties:
-- compatible: value should be "samsung,exynos5-mixer".
+- compatible: value should be one of the following:
+	1) "samsung,exynos5-mixer" <DEPRECATED>
+	2) "samsung,exynos4210-mixer"
+	3) "samsung,exynos5250-mixer"
+	4) "samsung,exynos5420-mixer"
+
 - reg: physical base address of the mixer and length of memory mapped
 	region.
 - interrupts: interrupt number to the cpu.
@@ -9,7 +14,7 @@ Required properties:
 Example:
 
 	mixer {
-		compatible = "samsung,exynos5-mixer";
+		compatible = "samsung,exynos5250-mixer";
 		reg = <0x14450000 0x10000>;
 		interrupts = <0 94 0>;
 	};
diff --git a/Documentation/fb/uvesafb.txt b/Documentation/fb/uvesafb.txt
index eefdd91d298a..f6362d88763b 100644
--- a/Documentation/fb/uvesafb.txt
+++ b/Documentation/fb/uvesafb.txt
@@ -81,17 +81,11 @@ pmipal  Use the protected mode interface for palette changes.
 
 mtrr:n  Setup memory type range registers for the framebuffer
         where n:
-              0 - disabled (equivalent to nomtrr) (default)
-              1 - uncachable
-              2 - write-back
-              3 - write-combining
-              4 - write-through
-
-        If you see the following in dmesg, choose the type that matches
-        the old one.  In this example, use "mtrr:2".
-...
-mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining
-...
+              0 - disabled (equivalent to nomtrr)
+              3 - write-combining (default)
+
+	Values other than 0 and 3 will result in a warning and will be
+	treated just like 3.
 
 nomtrr  Do not use memory type range registers.