This change updates the old_fb pointer only after acquiring the plane lock,
if there are no properties the fb cannot have been changed either, so
this works out correctly.
Found in a discussion with Rob Clark.
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
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: Daniel Stone <daniels@collabora.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel 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: Daniel Stone <daniels@collabora.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel 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: Daniel Stone <daniels@collabora.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel 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: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Amend kerneldoc a bit.]
Signed-off-by: Daniel 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: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel 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: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This saves some typing whenever a iteration over all the connector,
crtc or plane states in the atomic state is written, which happens
quite often.
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Consistently with other free functions, handle the NULL case without
oopsing.
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Users of the atomic state assume that if the pointer to a crtc, plane or
connector is not NULL in the respective object vector, than the state
for that object in *_states vector also won't be NULL. That assumption
was broken by drm_atomic_state_clear(), which would clear the state
pointer but leave the pointer to the object still set.
This fixes a NULL pointer dereference in i915 caused by the use of
drm_atomic_state_clear().
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Before, we would set the property, but also return -EINVAL because of a
broken fallthrough.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Active was here, and we allowed users to set it, but not to get it as
well.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Both the legacy and atomic helpers need to check whether a plane
supports a given pixel format. The code is currently duplicated, share
it.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[danvet: Slightly extend the docbook.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Commit 1da30627fc "drm: Add rotation value to
plane state" moved the rotation property to DRM core but only did the set
property part. This does the get property part as well.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Atomic state handling adds a lot of indirection and complexity between
simple updates and drivers. For easier debugging the diagnostic output
is therefore rather chatty. Which is great for tracking down atomic
issues, but really annoying otherwise.
Add a new DRM_DEBUG_ATOMIC to be able to filter this out.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
The atomic helpers rely on drm_atomic_state_clear() to reset an atomic
state if a retry is needed due to the w/w mutexes. The subsequent calls
to drm_atomic_get_{crtc,plane,...}_state() would then return the stale
pointers in state->{crtc,plane,...}_states.
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This is the infrastructure for DPMS ported to the atomic world.
Fundamental changes compare to legacy DPMS are:
- No more per-connector dpms state, instead there's just one per each
display pipeline. So if you clone either you have to unclone first
if you only want to switch off one screen, or you just switch of
everything (like all desktops do). This massively reduces complexity
for cloning since now there's no more half-enabled cloned configs to
consider.
- Only on/off, dpms standby/suspend are as dead as real CRTs. Again
reduces complexity a lot.
Now especially for backwards compat the really important part for dpms
support is that dpms on always succeeds (except for hw death and
unplugged cables ofc). Which means everything that could fail (like
configuration checking, resources assignments and buffer management)
must be done irrespective from ->active. ->active is really only a
toggle to change the hardware state. More precisely:
- Drivers MUST NOT look at ->active in their ->atomic_check callbacks.
Changes to ->active MUST always suceed if nothing else changes.
- Drivers using the atomic helpers MUST NOT look at ->active anywhere,
period. The helpers will take care of calling the respective
enable/modeset/disable hooks as necessary. As before the helpers
will carefully keep track of the state and not call any hooks
unecessarily, so still no double-disables or enables like with crtc
helpers.
- ->mode_set hooks are only called when the mode or output
configuration changes, not for changes in ->active state.
- Drivers which reconstruct the state objects in their ->reset hooks
or through some other hw state readout infrastructure must ensure
that ->active reflects actual hw state.
This just implements the core bits and helper logic, a subsequent
patch will implement the helper code to implement legacy dpms with
this.
v2: Rebase on top of the drm ioctl work:
- Move crtc checks to the core check function.
- Also check for ->active_changed when deciding whether a modeset
might happen (for the ALLOW_MODESET mode).
- Expose the ->active state with an atomic prop.
v3: Review from Rob
- Spelling fix in comment.
- Extract needs_modeset helper to consolidate the ->mode_changed ||
->active_changed checks.
v4: Fixup fumble between crtc->state and crtc_state.
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
The rotation property is shared by multiple drivers, so it makes sense
to store the rotation value (for atomic-converted drivers) in the common
plane state so that core code can eventually access it as well.
Cc: dri-devel@lists.freedesktop.org
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Copying 64 bit data from user space using get_user is not supported
on all architectures, and may result in the following build error.
ERROR: "__get_user_bad" [drivers/gpu/drm/drm.ko] undefined!
Avoid the problem by using copy_from_user.
Fixes: d34f20d6e2 ("drm: Atomic modeset ioctl")
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This is just a bit fallout from patch polishing and moving the
get_prop logic fully into the core:
- Drop EXPORT_SYMBOL and make the helpers static.
- Drop kerneldoc since not used by drivers.
- Move the cross-file function declarations only used by drm.ko
internally to an internal header.
v2: keep the gist of the comments, requested by Rob.
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
The atomic modeset ioctl can be used to push any number of new values
for object properties. The driver can then check the full device
configuration as single unit, and try to apply the changes atomically.
The ioctl simply takes a list of object IDs and property IDs and their
values.
Originally based on a patch from Ville Syrjälä, although it has mutated
(mutilated?) enough since then that you probably shouldn't blame it on
him ;-)
The atomic support is hidden behind the DRM_CLIENT_CAP_ATOMIC cap (to
protect legacy userspace) and drm.atomic module param (for now).
v2: Check for file_priv->atomic to make sure we only allow userspace
in-the-know to use atomic.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Expose the core connector state as properties so it can be updated via
atomic ioctl.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Expose the core plane state as properties, so they can be updated via
atomic ioctl.
v2: atomic property flag
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Add functions to check core plane/crtc state.
v2: comments, int-overflow checks, call from core rather than
helpers to be sure drivers can't find a way to bypass core
checks
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Once a driver is using atomic helpers for modeset, the next step is to
switch over to atomic properties. To do this, make sure that any
modeset objects have their ->atomic_{get,set}_property() vfuncs suitably
populated if they have custom properties (you did already remember to
plug in atomic-helper func for the legacy ->set_property() vfuncs,
right?), and then set DRIVER_ATOMIC bit in driver_features flag.
A new cap is introduced, DRM_CLIENT_CAP_ATOMIC, for the purposes of
shielding legacy userspace from atomic properties. Mostly for the
benefit of legacy DDX drivers that do silly things like getting/setting
each property at startup (since some of the new atomic properties will
be able to trigger modeset).
Signed-off-by: Rob Clark <robdclark@gmail.com>
[danvet: Squash in fixup patch to check for DRM_MODE_PROP_ATOMIC
instaed of the CAP define when filtering properties. Reported by
Tvrtko Uruslin, acked by Rob.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Since we won't be using the obj->properties->values[] array to shadow
property values for atomic drivers, we are going to need a vfunc for
getting prop values. Add that along w/ mandatory wrapper fxns.
v2: more comments and copypasta comment typo fix
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
As we add properties for all the standard plane/crtc/connector
attributes (in preperation for the atomic ioctl), we are going to want
to handle core state in core (rather than per driver). Intercepting the
core properties will be easier if the atomic_set_property vfuncs are not
called directly, but instead have a mandatory wrapper function (which
will later serve as the point to intercept core properties).
v2: more verbose comments and copypasta comment fix
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Useful since this way we can pass around just the state objects and
will get ther real object, too.
Specifically this allows us to again simplify the parameters for
set_crtc_for_plane.
v2: msm already has it's own specific plane_reset hook, don't forget
that one!
v3: Fixup kerneldoc, reported by 0-day builder.
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com> (v2)
Tested-by: Rob Clark <robdclark@gmail.com> (v2)
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Chasing plane->state->crtc of planes that are *not* part of the same
atomic update is racy, making it incredibly awkward (or impossible) to
do something simple like iterate over all planes and figure out which
ones are attached to a crtc.
Solve this by adding a bitmask of currently attached planes in the
crtc-state.
Note that the transitional helpers do not maintain the plane_mask. But
they only support the legacy ioctls, which have sufficient brute-force
locking around plane updates that they can continue to loop over all
planes to see what is attached to a crtc the old way.
Signed-off-by: Rob Clark <robdclark@gmail.com>
[danvet:
- Drop comments about locking in set_crtc_for_plane since they're a
bit misleading - we already should hold lock for the current crtc.
- Also WARN_ON if get_state on the old crtc fails since that should
have been done already.
- Squash in fixup to check get_plane_state return value, reported by
Dan Carpenter and acked by Rob Clark.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
I've forgotten to remove that in my per-plane locking patch.
Reported-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
This is an oversight from
commit f52b69f1ec
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Wed Nov 19 18:38:08 2014 +0100
drm/atomic: Don't overrun the connector array when hotplugging
Cc: Dave Airlie <airlied@redhat.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Yet another fallout from not considering DP MST hotplug. With the
previous patches we have stable indices, but it might still happen
that a connector gets added between when we allocate the array and
when we actually add a connector. Especially when we back off due to
ww mutex contention or similar issues.
So store the sizes of the arrays in struct drm_atomic_state and double
check them. We don't really care about races except that we want to
use a consistent value, so ACCESS_ONCE is all we need. And if we
indeed notice that we'd overrun the array then just give up and
restart the entire ioctl.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Otherwise the connector might have been unplugged and destroyed while
we didn't look. Yet another fallout from DP MST hotplugging that I
didn't consider.
To make sure we get this right add an appropriate WARN_ON to
drm_atomic_state_clear (obviously only when we actually have a state
to clear up). And reorder all the state_clear and backoff calls to
make it work out properly.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
I've totally forgotten that with DP MST connectors can now be
hotplugged. And failed to adapt Rob's drm_atomic_state code (which
predates connector hotplugging) to the new realities.
The first step is to make sure that the connector indices used to
access the arrays of pointers are stable. The connection mutex gives
us enough guarantees for that, which means we won't unecessarily block
on concurrent modesets or background probing.
So add a locking WARN_ON and shuffle the code slightly to make sure we
always hold the right lock.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Turned out to be much simpler on top of my latest atomic stuff than
what I've feared. Some details:
- Drop the modeset_lock_all snakeoil in drm_plane_init. Same
justification as for the equivalent change in drm_crtc_init done in
commit d0fa1af40e
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Sep 8 09:02:49 2014 +0200
drm: Drop modeset locking from crtc init function
Without these the drm_modeset_lock_init would fall over the exact
same way.
- Since the atomic core code wraps the locking switching it to
per-plane locks was a one-line change.
- For the legacy ioctls add a plane argument to the locking helper so
that we can grab the right plane lock (cursor or primary). Since the
universal cursor plane might not be there, or someone really crazy
might forgoe the primary plane even accept NULL.
- Add some locking WARN_ON to the atomic helpers for good paranoid
measure and to check that it all works out.
Tested on my exynos atomic hackfest with full lockdep checks and ww
backoff injection.
v2: I've forgotten about the load-detect code in i915.
v3: Thierry reported that in latest 3.18-rc vmwgfx doesn't compile any
more due to
commit 21e88620aa
Author: Rob Clark <robdclark@gmail.com>
Date: Thu Oct 30 13:39:04 2014 -0400
drm/vmwgfx: fix lock breakage
Rebased and fix this up.
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
So my original plan was that the drm core refcounts framebuffers like
with the legacy ioctls. But that doesn't work for a bunch of reasons:
- State objects might live longer than until the next fb change
happens for a plane. For example delayed cleanup work only happens
_after_ the pageflip ioctl has completed. So this definitely doesn't
work without the plane state holding its own references.
- The other issue is transition from legacy to atomic implementations,
where the driver works under a mix of both worlds. Which means
legacy paths might not properly update the ->fb pointer under
plane->state->fb. Which is a bit a problem when then someone comes
around and _does_ try to clean it up when it's long gone.
The second issue is just a bit a transition bug, since drivers should
update plane->state->fb in all the paths that aren't converted yet.
But a bit more robustness for the transition can't hurt - we pull
similar tricks with cleaning up the old fb in the transitional helpers
already.
The pattern for drivers that transition is
if (plane->state)
drm_atomic_set_fb_for_plane(plane->state, plane->fb);
inserted after the fb update has logically completed at the end of
->set_config (or ->set_base/mode_set if using the crtc helpers),
->page_flip, ->update_plane or any other entry point which updates
plane->fb.
v2: Update kerneldoc - copypasta fail.
v3: Fix spelling in the commit message (Sean).
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Some differences compared to Rob's patches again:
- Dropped the committed and checked booleans. Checking will be
internally enforced by always calling ->atomic_check before
->atomic_commit. And async handling needs to be solved differently
because the current scheme completely side-steps ww mutex deadlock
avoidance (and so either reinvents a new deadlock avoidance wheel or
like the current code just deadlocks).
- State for connectors needed to be added, since now they have a
full-blown drm_connector_state (so that drivers have something to
attach their own stuff to).
- Refcounting is gone. I plane to solve async updates differently,
since the lock-passing scheme doesn't cut it (since it abuses ww
mutexes). Essentially what we need for async is a simple ownership
transfer from the caller to the driver. That doesn't need full-blown
refcounting.
- The acquire ctx is a pointer. Real atomic callers should have that
on their stack, legacy entry points need to put the right one
(obtained by drm_modeset_legacy_acuire_ctx) in there.
- I've dropped all hooks except check/commit. All the begin/end
handling is done by core functions and is the same.
- commit/check are just thin wrappers that ensure that ->check is
always called.
- To help out with locking in the legacy implementations I've added a
helper to just grab all locks in the backoff case.
v2: Add notices that check/commit can fail with EDEADLK.
v3:
- More consistent naming for state_alloc.
- Add state_clear which is needed for backoff and retry.
v4: Planes/connectors can switch between crtcs, and we need to be
careful that we grab the state (and locks) for both the old and new
crtc. Improve the interface functions to ensure this.
v5: Add functions to grab affected connectors for a crtc and to recompute
the crtc->enable state. This is useful for both helper and atomic ioctl
code when e.g. removing a connector.
v6: Squash in fixup from Fengguang to use ERR_CAST.
v7: Add debug output.
v8: Make checkpatch happy about kcalloc argument ordering.
v9: Improve kerneldoc in drm_crtc.h
v10:
- Fix another kcalloc argument misorder I've missed.
- More polish for kerneldoc.
v11: Clarify the ownership rules for the state object. The new rule is
that a successful drm_atomic_commit (whether synchronous or asnyc)
always inherits the state and is responsible for the clean-up. That
way async and sync ->commit functions are more similar.
v12: A few bugfixes:
- Assign state->state pointers correctly when grabbing state objects -
we need to link them up with the global state.
- Handle a NULL crtc in set_crtc_for_plane to simplify code flow a bit
for the callers of this function.
v13: Review from Sean:
- kerneldoc spelling fixes
- Don't overallocate states->planes.
- Handle NULL crtc in set_crtc_for_connector.
v14: Sprinkle __must_check over all functions which do wait/wound
locking to make sure callers don't forget this. Since I have ;-)
v15: Be more explicit in the kerneldoc when functions can return
-EDEADLK what to do. And that every other -errno is fatal.
v16: Indent with tabs instead of space, spotted by Ander.
v17: Review from Thierry, small kerneldoc and other naming polish.
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Maarten Lankhorst