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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-09 16:04:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-09 16:04:31 -0700
commit2e17c5a97e231f3cb426f4b7895eab5be5c5442e (patch)
tree80871817427250200d6931a45ccb4833c4add74a /Documentation
parent5f097cd249f00683442c3e265d6f27d80fc83563 (diff)
parent774d8e34e46506222bb5e2888e3ef42b2775715f (diff)
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 ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/device-drivers.tmpl2
-rw-r--r--Documentation/DocBook/drm.tmpl271
-rw-r--r--Documentation/devicetree/bindings/drm/tilcdc/tilcdc.txt8
-rw-r--r--Documentation/devicetree/bindings/video/display-timing.txt1
-rw-r--r--Documentation/devicetree/bindings/video/exynos_hdmi.txt13
-rw-r--r--Documentation/devicetree/bindings/video/exynos_hdmiddc.txt7
-rw-r--r--Documentation/devicetree/bindings/video/exynos_hdmiphy.txt7
-rw-r--r--Documentation/devicetree/bindings/video/exynos_mixer.txt9
-rw-r--r--Documentation/fb/uvesafb.txt16
9 files changed, 259 insertions, 75 deletions
diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index fca34192cf8..cbfdf548663 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 6dd8d10d6b7..7d1278e7a43 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 e5f130159ae..fff10da5e92 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 150038552bc..e1d4a0b5961 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 589edee3739..323983be3c3 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 fa166d94580..41eee971562 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 858f4f9b902..162f641f763 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 9b2ea034356..3334b0a8e34 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 eefdd91d298..f6362d88763 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.