Some drm drivers populate their fb_ops with fb_sys_read/write fb sysfs
ops.

Create a drm_fb_helper function that wraps around these calls.

This is part of an effort to prevent drm drivers from calling fbdev
functions directly, in order to make fbdev emulation a top level drm
option.

v3:
- Fix kerneldoc errors

v2:
- Added kerneldocs
- Follow the drm way of aligning of arguments in func definitions
- Remove unnecessary checks for non NULL fb_info
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Some drm drivers call unlink_framebuffer. Create a drm_fb_helper function
that wraps around these calls.

This is part of an effort to prevent drm drivers from calling fbdev
functions directly, in order to make fbdev emulation a top level drm
option.

v2:
- Added kerneldocs
- Added a check for non-NULL fb_helper before proceeding. This will
  make the helpers work when we have a module param for fbdev emulation
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Every drm driver calls framebuffer_alloc, fb_alloc_cmap,
unregister_framebuffer, fb_dealloc_cmap and framebuffer_release in
order to emulate fbdev support.

Create drm_fb_helper functions that perform the above operations.

This is part of an effort to prevent drm drivers from calling fbdev
functions directly. It also removes repetitive code from drivers.

There are some drivers that call alloc_apertures after framebuffer_alloc
and some that don't. Make the helper always call alloc_apertures. This
would make certain drivers allocate memory for apertures but not use
them. Since it's a small amount of memory, it shouldn't be an issue.

v2:
- Added kerneldocs
- Added a check for non-NULL fb_helper before proceeding. This will
  make the helpers work when we have a module param for fbdev emulation
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is required to properly handle failing dpms calls.
When making a wait in i915 interruptible, I've noticed
that the dpms sequence could fail with -ERESTARTSYS because
it was waiting interruptibly for flips. So from now on
allow drivers to fail in their connector dpms callback.

Encoder and crtc dpms callbacks are unaffected.

Changes since v1:
- Update kerneldoc for the drm helper functions.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Resolve conflicts due to different merge order.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In intel it's useful to keep track of some state changes with old
crtc state vs new state, for example to disable initial planes or
when a modeset's prevented during fastboot.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NAnder Conselvan de Oliveira <conselvan2@gmail.com>
[danvet: squash in fixup for exynos provided by Maarten.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This can be a separate case from mode_changed, when connectors stay the
same but only the mode is different. Drivers may choose to implement specific
optimizations to prevent a full modeset for this case.

Changes since v1:
- Update kerneldocs slightly.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NAnder Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

By Vesa's DP 1.2 Spec this counter has 4 bits [3:0].

This mask is wrong since when the counter was introduced by myself
on commit ad9dc91b
Author: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Date:   Tue Sep 16 19:18:12 2014 -0400

    drm/i915: Fix Sink CRC
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NSivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Two nice things here:
- drm_dev_register will truly register everything in the right order
  if the driver doesn't have a ->load callback. Before this we had to
  init the primary mode_group after the device nodes where already
  registered.

- Less things to keep track of when reworking the connector locking,
  yay!
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Now that dp mst hotplug takes all locks we can amend the locking rules
for the iterators. This is needed before we can roll these out in the
atomic code to avoid getting burried in WARNINGs.

v2: Rebase onto the extracted list locking assert and add a comment to
explain the rules.

v3: Fixup German->English translation fail in the comment.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Ever since framebuffers are reference counted we have a special lock
for the global fb list. Make sure users of that list do hold that
lock when using the new iterators.
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Because of DP MST connectors can now be hotplugged and we must hold
the right lock when walking the connector lists.  Enforce this by
checking the locking in our shiny new list walking macros.

v2: Extract the locking check into a small static inline helper to
help readability. This will be more important when we make the
read list access rules more complicated in later patches. Inspired by
comments from Chris. Unfortunately, due to header loops around the
definition of struct drm_device the function interface is a bit funny.

v3: Encoders aren't hotadded/removed. For each dp mst encoder we
statically create one fake encoder per pipe so that we can support as
many mst sinks as the hw can (Dave).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

And roll them out across drm_* files. The point here isn't code
prettification (it helps with that too) but that some of these lists
aren't static any more. And having macros will gives us a convenient
place to put locking checks into.

I didn't add an iterator for props since that's only used by a
list_for_each_entry_safe in the driver teardown code.

Search&replace was done with the below cocci spatch. Note that there's
a bunch more places that didn't match and which would need some manual
changes, but I've intentially left these out for this mostly automated
patch.

iterator name drm_for_each_crtc;
struct drm_crtc *crtc;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+ drm_for_each_crtc (crtc, dev) {
...
}

@@
iterator name drm_for_each_encoder;
struct drm_encoder *encoder;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+ drm_for_each_encoder (encoder, dev) {
...
}

@@
iterator name drm_for_each_fb;
struct drm_framebuffer *fb;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(fb, &dev->mode_config.fb_list, head) {
+ drm_for_each_fb (fb, dev) {
...
}

@@
iterator name drm_for_each_connector;
struct drm_connector *connector;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+ drm_for_each_connector (connector, dev) {
...
}
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

No need to pass the planelist when everyone just uses
dev->mode_config.plane_list anyway.

I want to add a pile more of iterators with unified (obj, dev)
arguments. This is just prep.
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

The context functions are not used by the i915 driver and should not
be used by modeset drivers. These driver functions contain several bugs
and security holes. This change makes these functions optional can be
turned on by a setting, they are turned off by default for modeset
driver with the exception of the nouvea driver that may require them with
an old version of libdrm.

The previous attempt was

commit 7c510133
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Aug 8 15:41:21 2013 +0200

    drm: mark context support as a legacy subsystem

but this had to be reverted

commit c21eb21c
Author: Dave Airlie <airlied@redhat.com>
Date:   Fri Sep 20 08:32:59 2013 +1000

    Revert "drm: mark context support as a legacy subsystem"

v2: remove returns from void function, and formatting (Daniel Vetter)

v3:
- s/Nova/nouveau/ in the commit message, and add references to the
  previous attempts
- drop the part touching the drm hw lock, that should be a separate
  patch.

Signed-off-by: Peter Antoine <peter.antoine@intel.com> (v2)
Cc: Peter Antoine <peter.antoine@intel.com> (v2)
Reviewed-by: NPeter Antoine <peter.antoine@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Use kvfree() instead of open-coding it.
Signed-off-by: NPekka Enberg <penberg@kernel.org>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We can have exactly 4GB sized ppgtt with 32bit system.
size_t is inadequate for this.

v2: Convert a lot more places (Daniel)
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I've only seen this once, and I failed to capture the
lockdep backtrace, but I did some investigations.

If we are calling into the MST layer from EDID probing,
we have the mode_config mutex held, if during that EDID
probing, the MST hub goes away, then we can get a deadlock
where the connector destruction function in the driver
tries to retake the mode config mutex.

This offloads connector destruction to a workqueue,
and avoid the subsequenct lock ordering issue.
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

We use the same check already in the atomic core, so might as well
make this official. And it's also reused in e.g. i915.

Motivated by Maarten's idea to extract a connector_changed state out
of mode_changed.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-By: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

This header file declares prototypes of functions that are no longer
used. Remove this file and all references to it.
Signed-off-by: NThierry Reding <treding@nvidia.com>

This patch adds a kms driver for the virtio gpu.  The xorg modesetting
driver can handle the device just fine, the framebuffer for fbcon is
there too.

Qemu patches for the host side are under review currently.

The pci version of the device comes in two variants: with and without
vga compatibility.  The former has a extra memory bar for the vga
framebuffer, the later is a pure virtio device.  The only concern for
this driver is that in the virtio-vga case we have to kick out the
firmware framebuffer.

Initial revision has only 2d support, 3d (virgl) support requires
some more work on the qemu side and will be added later.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>

for_each_*_in_state validate array index after
access to array elements, thus perform out of bounds read.

Fix this by validating index in the first place and read
array element iff validation was successful.

Fixes: df63b999 ("drm/atomic: Add for_each_{connector,crtc,plane}_in_state helper macros")
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Atomic modesetting: now with modesetting support.

v2: Moved drm_atomic_set_mode_prop_for_crtc from previous patch; removed
    state->active fiddling, documented return code. Changed property
    type to DRM_MODE_PROP_BLOB.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Tested-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add a blob property tracking the current mode to the CRTC state, and
ensure it is properly updated and referenced.

v2: Continue using crtc_state->mode inside getcrtc, instead of reading
    out the mode blob. Use IS_ERR and PTR_ERR from create_blob. Move
    set_mode_prop_for_crtc to later patch where it actually gets used.
    Enforce !!state->enable == !!state->mode_blob inside
    drm_atomic_crtc_check.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Tested-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add a new helper, to be used later for blob property management, that
sets the mode for a CRTC state, as well as updating the CRTC enable/active
state at the same time.

v2: Do not touch active/mode_changed in CRTC state. Document return
    value. Remove stray drm_atomic_set_mode_prop_for_crtc declaration.

v3: Remove i915 changes, and leave it directly bashing crtc_state->mode
    for the meantime.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Tested-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add an ioctl which allows users to create blob properties from supplied
data. Currently this only supports modes, creating a drm_display_mode from
the userspace drm_mode_modeinfo.

v2: Removed size/type checks.
    Rebased on new patches to allow error propagation from create_blob,
    as well as avoiding double-allocation.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@intel.com>
Tested-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Move the drm_display_mode <-> drm_mode_modeinfo conversion functions
from drm_crtc.c to drm_modes.c, and make them non-static so that others
can use them.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Tested-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Allow drm_bridge objects to link to each other in order to form an encoder
chain. The requirement for creating a chain of bridges comes because the
MSM drm driver uses up its encoder and bridge objects for blocks within
the SoC itself. There isn't anything left to use if the SoC display output
is connected to an external encoder IC. Having an additional bridge
connected to the existing bridge helps here. In general, it is possible for
platforms to have  multiple devices between the encoder and the
connector/panel that require some sort of configuration.

We create drm bridge helper functions corresponding to each op in
'drm_bridge_funcs'. These helpers call the corresponding
'drm_bridge_funcs' op for the entire chain of bridges. These helpers are
used internally by drm_atomic_helper.c and drm_crtc_helper.c.

The drm_bridge_enable/pre_enable helpers execute enable/pre_enable ops of
the bridge closet to the encoder, and proceed until the last bridge in the
chain is enabled. The same holds for drm_bridge_mode_set/mode_fixup
helpers. The drm_bridge_disable/post_disable helpers disable the last
bridge in the chain first, and proceed until the first bridge in the chain
is disabled.

drm_bridge_attach() remains the same. As before, the driver calling this
function should make sure it has set the links correctly. The order in
which the bridges are connected to each other determines the order in which
the calls are made. One requirement is that every bridge in the chain
should point the parent encoder object. This is required since bridge
drivers expect a valid encoder pointer in drm_bridge. For example, consider
a chain where an encoder's output is connected to bridge1, and bridge1's
output is connected to bridge2:

	/* Like before, attach bridge to an encoder */
	bridge1->encoder = encoder;
	ret = drm_bridge_attach(dev, bridge1);
	..

	/*
	 * set the first bridge's 'next' bridge to bridge2, set its encoder
	 * as bridge1's encoder
	 */
	bridge1->next = bridge2
	bridge2->encoder = bridge1->encoder;
	ret = drm_bridge_attach(dev, bridge2);

	...
	...

This method of bridge chaining isn't intrusive and existing drivers that
use drm_bridge will behave the same way as before. The bridge helpers also
cleans up the atomic and crtc helper files a bit.
Reviewed-by: NJani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is a convenience function to add all planes for a crtc,
similar to add_affected_connectors. This will be used in
drm_atomic_helper_check_modeset, but drivers can call it too
when they need to recalculate all state.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Amend kerneldoc a bit.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drm_atomic_helper_commit_planes calls all atomic_begin's first,
then updates all planes, finally calling atomic_flush.

Some drivers may want to things like disabling irq's
from their atomic_begin, in which case a second call to atomic_begin
will splat. By using commit_planes_on_crtc on each crtc in the
atomic state they'll evade that issue.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Extend kerneldoc a bit as discussed with Maarten on irc.]
[danvet: Squash in fixup to check for crtc_funcs in all places.
Reported by Dan Carpenter.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Drivers may need to store the state of shared resources, such as PLLs
or FIFO space, into the atomic state. Allow this by making it possible
to subclass drm_atomic_state.

Changes since v1:
- Change member names for functions to atomic_state_(alloc,clear)
- Change __drm_atomic_state_new to drm_atomic_state_init
- Allow free function to be overridden too, in case extra memory is
  allocated in alloc.
Changes since v2:
- Rename *_default_free to default_release, to make clear it doesn't
  free the state object itself.

Cc: dri-devel@lists.freedesktop.org
Acked-by: NAnder Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Commit 4f71d0cb ("drm/dp: add a hw mutex around the transfer
functions. (v2)"), renamed the functions drm_dp_aux_register_i2c_bus()
and drm_dp_aux_unregister_i2c_bus() to drm_dp_aux_register() and
drm_dp_aux_unregister(), respectively. However, a comment referring to
the original names was not updated in the DP helper header file. Hence,
correct these names.
Signed-off-by: NJon Hunter <jonathanh@nvidia.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There are cases where we want to test if a given object is
part of the state, but don't want to add them if they're not.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is useful for drivers which have their own modeset infrastructure
but want to reuse most of the legacy state frobbery from the helpers.
i915 wants this.

v2: Add header declaration.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Reference-count drm_property_blob objects, changing the API to
ref/unref.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Squash in kerneldoc fixup from Daniel Stone.]
[danvet: Squash in Oops fix from Thiery Reding.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Also treat it as a proper boolean.

Cc: Todd Previte <tprevite@gmail.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Create a new global blob_lock mutex, which protects the blob property
list from insertion and/or deletion.
Signed-off-by: NDaniel Stone <daniels@collabora.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Displayport compliance test 4.2.2.6 requires that a source device be capable of
detecting a corrupt EDID. The test specification states that the sink device
sets up the EDID with an invalid checksum. To do this, the sink sets up an
invalid EDID header, expecting the source device to generate the checksum and
compare it to the value stored in the last byte of the block data.

Unfortunately, the DRM EDID reading and parsing functions are actually too good
in this case; the header is fixed before the checksum is computed and thus the
test never sees the invalid checksum. This results in a failure to pass the
compliance test.

To correct this issue, when the EDID code detects that the header is invalid,
a flag is set to indicate that the EDID is corrupted. In this case, it sets
edid_corrupt flag and continues with its fix-up code. This flag is also set in
the case of a more seriously damaged header (fixup score less than the
threshold). For consistency, the edid_corrupt flag is also set when the
checksum is invalid as well.

V2:
- Removed the static bool global
- Added a bool to the drm_connector struct to reaplce the static one for
  holding the status of raw edid header corruption detection
- Modified the function signature of the is_valid function to take an
  additional parameter to store the corruption detected value
- Fixed the other callers of the above is_valid function
V3:
- Updated the commit message to be more clear about what and why this
  patch does what it does.
- Added comment in code to clarify the operations there
- Removed compliance variable and check_link_status update; those
  have been moved to a later patch
- Removed variable assignment from the bottom of the test handler
V4:
- Removed i915 tag from subject line as the patch is not i915-specific
V5:
- Moved code causing a compilation error to this patch where the variable
  is actually declared
- Maintained blank lines / spacing so as to not contaminate the patch
V6:
- Removed extra debug messages
- Added documentation to for the added parameter on drm_edid_block_valid
- Fixed more whitespace issues in check_link_status
- Added a clear of the header_corrupt flag to the end of the test handler
  in intel_dp.c
- Changed the usage of the new function prototype in several places to use
  NULL where it is not needed by compliance testing
V7:
- Updated to account for long_pulse flag propagation
V8:
- Removed clearing of header_corrupt flag from the test handler in intel_dp.c
- Added clearing of header_corrupt flag in the drm_edid_block_valid function
V9:
- Renamed header_corrupt flag to edid_corrupt to more accurately reflect its
  value and purpose
- Updated commit message
V10:
- Updated for versioning and patch swizzle
- Revised the title to more accurately reflect the nature and contents of
  the patch
- Fixed formatting/whitespace problems
- Added set flag when computed checksum is invalid
Signed-off-by: NTodd Previte <tprevite@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Acked-by: NDave Airlie <airlied@redhat.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Add support for enabling codec wakeup override signal to allow
re-enumeration of the controller on SKL after resume from low power state.

In SKL, HDMI/DP codec and PCH HD Audio Controller are in different power
wells, so it's necessary to reset display audio codecs when power well on,
otherwise display audio codecs will disappear when resume from low power
state.
Reset steps when power on:
    enable codec wakeup -> azx_init_chip() -> disable codec wakeup

v3 by Jani: Simplify to only support toggling the appropriate chicken bit.

v4 by Han: add explanation and specify the hw swquence.
Signed-off-by: NLu, Han <han.lu@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>