Skip to content

K
Kernel

openeuler / Kernel
1 年多 前同步成功

通知 8
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 17 6月, 2013 1 次提交
  3. 11 6月, 2013 4 次提交
  5. 13 5月, 2013 1 次提交
  7. 03 5月, 2013 1 次提交
  9. 30 4月, 2013 2 次提交
    • V
      drm: Kill user_modes list and the associated ioctls · c55b6b3d
      由 Ville Syrjälä 提交于 
      There is no way to use modes added to the user_modes list. We never
look at the contents of said list in the kernel, and the only operations
userspace can do are attach and detach. So the only "benefit" of this
interface is wasting kernel memory.

Fortunately it seems no real user space application ever used these
ioctls. So just kill them.

Also remove the prototypes for the non-existing drm_mode_addmode_ioctl()
and drm_mode_rmmode_ioctl() functions.

v2: Use drm_noop instead of completely removing the ioctls
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
      c55b6b3d
    • V
      drm: Silence some sparse warnings · ea9cbb06
      由 Ville Syrjälä 提交于 
      drivers/gpu/drm/drm_pci.c:155:5: warning: symbol 'drm_pci_set_busid' was not declared. Should it be static?
drivers/gpu/drm/drm_pci.c:197:5: warning: symbol 'drm_pci_set_unique' was not declared. Should it be static?
drivers/gpu/drm/drm_pci.c:269:5: warning: symbol 'drm_pci_agp_init' was not declared. Should it be static?

drivers/gpu/drm/drm_crtc.c:181:1: warning: symbol 'drm_get_dirty_info_name' was not declared. Should it be static?
drivers/gpu/drm/drm_crtc.c:1123:5: warning: symbol 'drm_mode_group_init' was not declared. Should it be static?

drivers/gpu/drm/drm_modes.c:918:6: warning: symbol 'drm_mode_validate_clocks' was not declared. Should it be static?
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
      ea9cbb06
  11. 22 4月, 2013 1 次提交
  13. 16 4月, 2013 1 次提交
  15. 12 4月, 2013 1 次提交
  17. 28 3月, 2013 1 次提交
  19. 28 2月, 2013 2 次提交
  21. 22 2月, 2013 1 次提交
  23. 20 2月, 2013 3 次提交
  25. 18 2月, 2013 1 次提交
  27. 14 2月, 2013 1 次提交
    • D
      drm: review locking for drm_fb_helper_restore_fbdev_mode · 6aed8ec3
      由 Daniel Vetter 提交于 
      ... it's required. Fix up exynos and the cma helper, and add a
corresponding WARN_ON to drm_fb_helper_restore_fbdev_mode.

Note that tegra calls the fbdev cma helper restore function also from
it's driver-load callback. Which is a bit against current practice,
since usually the call is only from ->lastclose, and initial setup is
done by drm_fb_helper_initial_config.

Also add the relevant drm DocBook entry.

v2: Add promised WARN to restore_fbdev_mode.
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      6aed8ec3
  29. 21 1月, 2013 17 次提交
    • D
      drm: don't hold crtc mutexes for connector ->detect callbacks · 7b24056b
      由 Daniel Vetter 提交于 
      The coup de grace of the entire journey. No more dropped frames every
10s on my testbox!

I've tried to audit all ->detect and ->get_modes callbacks, but things
became a bit fuzzy after trying to piece together the umpteenth
implemenation. Afaict most drivers just have bog-standard output
register frobbing with a notch of i2c edid reading, nothing which
could potentially race with the newly concurrent pageflip/set_cursor
code. The big exception is load-detection code which requires a
running pipe, but radeon/nouveau seem to to this without touching any
state which can be observed from page_flip (e.g. disabled crtcs
temporarily getting enabled and so a pageflip succeeding).

The only special case I could find is the i915 load detect code. That
uses the normal modeset interface to enable the load-detect crtc, and
so userspace could try to squeeze in a pageflip on the load-detect
pipe. So we need to grab the relevant crtc mutex in there, to avoid
the temporary crtc enabling to sneak out and be visible to userspace.

Note that the sysfs files already stopped grabbing the per-crtc locks,
since I didn't want to bother with doing a interruptible
modeset_lock_all. But since there's very little in-between breakage
(essentially just the ability for userspace to pageflip on load-detect
crtcs when it shouldn't on the i915 driver) I figured I don't need to
bother.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      7b24056b
    • D
      drm: only grab the crtc lock for pageflips · b4d5e7d1
      由 Daniel Vetter 提交于 
      The pagelip ioctl itself is rather simply, so the hard work for this
patch is auditing all the drivers:

- exynos: Pageflip is protect with dev->struct_mutex and ...
  synchronous. But nothing fancy going on, besides a check whether the
  crtc is enabled, which should probably be somewhere in the drm core
  so that we have unified behaviour across all drivers.

- i915: hw-state is protected with dev->struct_mutex, the delayed
  unpin work together with the other stuff the pageflip complete irq
  handler needs is protected by the event_lock spinlock.

- nouveau: With the pin/unpin functions fixed, everything looks safe:
  A bit of ttm wrestling and refcounting, and a few channel accesses.
  The later are either already proteced sufficiently, or are now safe
  with the channel locking introduced to make cursor updates safe.

- radeon: The irq_get/put functions look a bit race, since the
  atomic_inc/dec isn't protect with locks. Otoh they're all per-crtc,
  so we should be safe with per-crtc locking from the drm core. Then
  there's tons of per-crtc register access, which could potentially go
  through the indirect reg acces. But that's fixed to make cursor
  updates concurrent. Bookeeping for the drm even is also protected
  with the even_lock, which also protects against the pageflip irq
  handler since radeon hw seems to have no way to queue these up
  asynchronously. Otherwise just a bit of ttm-based buffer handling
  and fencing, which is now safe with the previous patch to hold
  bdev->fence_lock while grabbing the ttm fence.

- shmob: Only one crtc. That's an easy one ...

- vmwgfx: As usual a bit special with tons different things:
  - Flippable check using is_implicit and num_implicit. Changes to
    those seem to be nicely covered with the global modeset lock, so
    we should be fine.
  - Some dirty cliprect handling stuff, or at least that is my guess.
    Looks like it's fine since either it's per-crtc, invariant or
    (like the execbuf stuff launched) protected otherwise.
  - Adding the actual flip to the fence_event list. On a quick look
    this seems to have solid locking in place, too.
  ... but generally this is all way over my head.

- imx: Impressive display of races between the page_flip
  implementation and the irq handler. Also, ipu_drm_set_base which
  gets eventually called from the irq handler to update the display
  base isn't really protected against concurrent set_config calls from
  process context.  In any case, going for per-crtc locking won't make
  this worse, so nothing to do.

- omap: The new async callback code merged into 3.8 seems to have
  solid locking in place, and there doesn't seem to be any shared
  state at risk. Especially since the callbacks still use
  modeset_lock_all and are so not converted.

v2: Update omapdrm analysis to 3.8 code per the discussion with Rob
Clark.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      b4d5e7d1
    • D
      drm: optimize drm_framebuffer_remove · b62584e3
      由 Daniel Vetter 提交于 
      Now that all framebuffer usage is properly refcounted, we are no
longer required to hold the modeset locks while dropping the last
reference. Hence implemented a fastpath which avoids the potential
stalls associated with grabbing mode_config.lock for the case where
there's no other reference around.

Explain in a big comment why it is safe. Also update kerneldocs with
the new locking rules around drm_framebuffer_remove.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      b62584e3
    • D
      drm: refcounting for crtc framebuffers · b0d12325
      由 Daniel Vetter 提交于 
      With the prep patch to encapsulate ->set_crtc calls, this is now
rather easy. Hooray for inconsistent semantics between ->set_crtc and
->page_flip, where the driver callback is supposed to update the fb
pointer, and ->update_plane, where the drm core does the same.

Also, since the drm core functions check crtc->fb before calling into
driver callbacks, we can't really reduce the critical sections
protected by the mode_config locks.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      b0d12325
    • D
      drm: refcounting for sprite framebuffers · 6c2a7532
      由 Daniel Vetter 提交于 
      Now plane->fb holds a reference onto it's framebuffer. Nothing too
fancy going on here:
- Extract __drm_framebuffer_unreference to be called when we know
  we're not dropping the last reference, e.g. useful in the fb cleanup
  code.
- Reduce the locked sections in the set_plane ioctl to only protect
  plane->fb/plane->crtc and the driver callback (i.e. hw state).
  Everything either doesn't disappear (crtc, plane) or is refcounted
  (fb), and all the data we check is invariant over the respective
  object's lifetimes.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      6c2a7532
    • D
      drm: fb refcounting for dirtyfb_ioctl · 4ccf097f
      由 Daniel Vetter 提交于 
      We only need to ensure that the fb stays around for long enough. While
at it, only grab the modeset locks when we need them (since most
drivers don't implement the dirty callback, this should help jitter
and stalls when using the generic modeset driver).
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      4ccf097f
    • D
      drm: don't take modeset locks in getfb ioctl · 58c0dca1
      由 Daniel Vetter 提交于 
      We only need to push the fb unreference a bit down. While at it,
properly pass the return value from ->create_handle back to userspace.

Most drivers either return -ENODEV if they don't have a concept of
buffer objects (ast, cirrus, ...) or just install a handle for the
underlying gem object (which is ok since we hold a reference on that
through the framebuffer).

v2: Split out the ->create_handle rework in the individual drivers.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      58c0dca1
    • D
      drm: push modeset_lock_all into ->fb_create driver callbacks · 468174f7
      由 Daniel Vetter 提交于 
      And drop it where it's not needed. Most driver just lookup the gem
object, allocate an fb struct, fill in all the useful fields and then
register it with drm_framebuffer_init.

All of these operations are already separately locked, and since we
only put the fb into the fpriv->fbs list _after_ having called
->fb_create, we can't also race with rmfb. We can otoh race with other
ioctls that put the framebuffer to use, but all drivers have been
reorganized already to call drm_framebuffer_init last in the fb
creation sequence.

So essentially, we can completely remove any modeset locks from the
addfb ioctl paths. Yeah!

Also, reference-counting is solid - we get a reference from fb_create
which we transfer to the fpriv->fbs list. And after unlocking the
fpriv->fbs_lock we don't touch the framebuffer any longer. Furthermore
drm_framebuffer_init has added a 2nd reference for the idr lookup, and
any access through that table will do it's own refcounting.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      468174f7
    • D
      drm: nest modeset locks within fpriv->fbs_lock · 7d331595
      由 Daniel Vetter 提交于 
      Atm we still need to unconditionally take the modeset locks in the
rmfb paths. But eventually we only want to take them if there are
other users around as a slow-path. This way sane userspace avoids
blocking on edid reads and other stuff in rmfb if it ensures that the
fb isn't used anywhere by a crtc/plane.

We can do a quick check for such other users once framebuffers are
properly refcounting by locking at the refcount - if it's more than 1,
there are other users left. Again, rmfb racing against other ioctls
isn't a real problem, userspace is allowed to shoot its foot.

This patch just prepares this by moving the modeset locks to nest
within fpriv->fbs_lock. Now the distinction between the fbs_lock and
the device-global fb_lock is clear, since we need to hold the fbs_lock
outside of any modeset_locks in fb_release.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      7d331595
    • D
      drm: reference framebuffers which are on the idr · 2b677e8c
      由 Daniel Vetter 提交于 
      Since otherwise looking and reference-counting around
drm_framebuffer_lookup will be an unmanageable mess. With this change,
an object can either be found in the idr and will stay around once we
incremented the reference counter. Or it will be gone for good and
can't be looked up using its id any more.

Atomicity is guaranteed by the dev->mode_config.fb_lock. The
newly-introduce fpriv->fbs_lock looks a bit redundant, but the next
patch will shuffle the locking order between these two locks and all
the modeset locks taken in modeset_lock_all, so we'll need it.

Also, since userspace could do really funky stuff and race e.g. a
getresources with an rmfb, we need to make sure that the kernel
doesn't fall over trying to look-up an inexistent fb, or causing
confusion by having two fbs around with the same id. Simply reset the
framebuffer id to 0, which marks it as reaped. Any lookups of that id
will fail, so the object is really gone for good from userspace's pov.

Note that we still need to protect the "remove framebuffer from all
use-cases" and the final unreference with the modeset-lock, since most
framebuffer use-sites don't implement proper reference counting yet.
We can only lift this once _all_ users are converted.

With this change, two references are held on alife, but unused
framebuffers:
- The reference for the idr lookup, created in this patch.
- For user-created framebuffers the fpriv->fbs reference, for
  driver-private fbs the driver is supposed to hold it's own last
  reference.

Note that the dev->mode_config.fb_list itself does _not_ hold a
reference onto the framebuffers (this list is essentially only used
for debugfs files). Hence if there's anything left there when the
driver has cleaned up all it's modeset resources, this is a ref-leak.
WARN about it.

Now we only need to fix up all other places to properly reference
count framebuffers.

v2: Fix spelling fail in a comment spotted by Rob Clark.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      2b677e8c
    • D
      drm: revamp framebuffer cleanup interfaces · 36206361
      由 Daniel Vetter 提交于 
      We have two classes of framebuffer
- Created by the driver (atm only for fbdev), and the driver holds
  onto the last reference count until destruction.
- Created by userspace and associated with a given fd. These
  framebuffers will be reaped when their assoiciated fb is closed.

Now these two cases are set up differently, the framebuffers are on
different lists and hence destruction needs to clean up different
things. Also, for userspace framebuffers we remove them from any
current usage, whereas for internal framebuffers it is assumed that
the driver has done this already.

Long story short, we need two different ways to cleanup such drivers.
Three functions are involved in total:
- drm_framebuffer_remove: Convenience function which removes the fb
  from all active usage and then drops the passed-in reference.
- drm_framebuffer_unregister_private: Will remove driver-private
  framebuffers from relevant lists and drop the corresponding
  references. Should be called for driver-private framebuffers before
  dropping the last reference (or like for a lot of the drivers where
  the fbdev is embedded someplace else, before doing the cleanup
  manually).
- drm_framebuffer_cleanup: Final cleanup for both classes of fbs,
  should be called by the driver's ->destroy callback once the last
  reference is gone.

This patch just rolls out the new interfaces and updates all drivers
(by adding calls to drm_framebuffer_unregister_private at all the
right places)- no functional changes yet. Follow-on patches will move
drm core code around and update the lifetime management for
framebuffers, so that we are no longer required to keep framebuffers
alive by locking mode_config.mutex.

I've also updated the kerneldoc already.

vmwgfx seems to again be a bit special, at least I haven't figured out
how the fbdev support in that driver works. It smells like it's
external though.

v2: The i915 driver creates another private framebuffer in the
load-detect code. Adjust its cleanup code, too.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      36206361
    • D
      drm: create drm_framebuffer_lookup · 786b99ed
      由 Daniel Vetter 提交于 
      And replace all fb lookups with it. Also add a WARN to
drm_mode_object_find since that is now no longer the blessed interface
to look up an fb. And add kerneldoc to both functions.

This only updates all callsites, but immediately drops the acquired
refence again. Hence all callers still rely on the fact that a mode fb
can't disappear while they're holding the struct mutex. Subsequent
patches will instate proper use of refcounts, and then rework the rmfb
and unref code to no longer serialize fb destruction with the
mode_config lock. We don't want that since otherwise a compositor
might end up stalling for a few frames in rmfb.

v2: Don't use kref_get_unless_zero - Greg KH doesn't like that kind of
interface.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      786b99ed
    • D
      drm: revamp locking around fb creation/destruction · 4b096ac1
      由 Daniel Vetter 提交于 
      Well, at least step 1. The goal here is that framebuffer objects can
survive outside of the mode_config lock, with just a reference held
as protection. The first step to get there is to introduce a special
fb_lock which protects fb lookup, creation and destruction, to make
them appear atomic.

This new fb_lock can nest within the mode_config lock. But the idea is
(once the reference counting part is completed) that we only quickly
take that fb_lock to lookup a framebuffer and grab a reference,
without any other locks involved.

vmwgfx is the only driver which does framebuffer lookups itself, also
wrap those calls to drm_mode_object_find with the new lock.

Also protect the fb_list walking in i915 and omapdrm with the new lock.

As a slight complication there's also the list of user-created fbs
attached to the file private. The problem now is that at fclose() time
we need to walk that list, eventually do a modeset call to remove the
fb from active usage (and are required to be able to take the
mode_config lock), but in the end we need to grab the new fb_lock to
remove the fb from the list. The easiest solution is to add another
mutex to protect this per-file list.

Currently that new fbs_lock nests within the modeset locks and so
appears redudant. But later patches will switch around this sequence
so that taking the modeset locks in the fb destruction path is
optional in the fastpath. Ultimately the goal is that addfb and rmfb
do not require the mode_config lock, since otherwise they have the
potential to introduce stalls in the pageflip sequence of a compositor
(if the compositor e.g. switches to a fullscreen client or if it
enables a plane). But that requires a few more steps and hoops to jump
through.

Note that framebuffer creation/destruction is now double-protected -
once by the fb_lock and in parts by the idr_lock. The later would be
unnecessariy if framebuffers would have their own idr allocator. But
that's material for another patch (series).

v2: Properly initialize the fb->filp_head list in _init, otherwise the
newly added WARN to check whether the fb isn't on a fpriv list any
more will fail for driver-private objects.

v3: Fixup two error-case unlock bugs spotted by Richard Wilbur.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      4b096ac1
    • D
      drm: only take the crtc lock for ->cursor_move · dac35663
      由 Daniel Vetter 提交于 
      ->cursor_move uses mostly the same facilities in drivers as
->cursor_set, so pretty much nothing to fix up:

- ast/gma500/i915: They all use per-crtc registers to update the
  cursor position. ast again touches the global cursor cache, but
  that's ok since there's only one crtc.

- nouveau: nv50+ is again special, updates happen through the per-crtc
  channel (without pushbufs), so it's not protected by the new evo
  lock introduced earlier. But since this channel is per-crtc, we
  should be fine anyway.

- radeon: A bit a mess: avivo asics need a workaround when both output
  pipes are enabled, which means it'll access the crtc list. Just
  reading that flag is ok though as long as radeon _always_ grabs all
  locks when changing the crtc configuration. Which means with the
  current scheme it cannot do an optimized modeset which only locks
  the relevant crtcs. This can be fixed though by introducing a bit of
  global state with separate locks and ensure in the modeset code that
  the cursor will be updated appropriately when enabling the 2nd pipe
  (on affected asics).

- vmwgfx: I still don't understand what it's doing exactly, so apply
  the same trick for now.

v2: Fixup unlocking for the error cases, spotted by Richard Wilbur.

v3: Another error-case fixup.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      dac35663
    • D
      drm: only take the crtc lock for ->cursor_set · bfb89928
      由 Daniel Vetter 提交于 
      First convert ->cursor_set to only take the crtc lock, since that
seems to be the function with the least amount of state - the core
ioctl function doesn't check anything which can change at runtime, so
we don't have any object lifetime issues to contend.

The only thing which is important is that the driver's implementation
doesn't touch any state outside of that single crtc which is not yet
properly protected by other locking:

- ast: access the global ast->cache_kmap. Luckily we only have on crtc
  on this driver, so this is fine. Add a comment.

- gma500: calls gma_power_begin|and and psb_gtt_pin|unpin, both which
  have their own locking to protect their state. Everything else is
  crtc-local.

- i915: touches a bit of global gem state, all protected by the One
  Lock to Rule Them All (dev->struct_mutex).

- nouveau: Pre-nv50 is all nice, nv50+ uses the evo channels to queue
  up all display changes. And some of these channels are device
  global. But this is fine now since the previous patch introduced an
  evo channel mutex.

- radeon: Uses some indirect register access for cursor updates, but
  with the previous patches to protect these indirect 2-register
  access patterns with a spinlock, this should be fine now, too.

- vmwgfx: I have no idea how that works - update_cursor_position
  doesn't take any per-crtc argument and I haven't figured out any
  other place where this could be set in some form of a side-channel.
  But vmwgfx definitely has more than one crtc (or at least can
  register more than one), so I have no idea how this is supposed to
  not fail with the current code already. Hence take the easy way out
  and simply acquire all locks (which requires dropping the crtc lock
  the core acquired for us). That way it's not worse off for
  consistency than the old code.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      bfb89928
    • D
      drm: add per-crtc locks · 29494c17
      由 Daniel Vetter 提交于 
      *drumroll*

The basic idea is to protect per-crtc state which can change without
touching the output configuration with separate mutexes, i.e.  all the
input side state to a crtc like framebuffers, cursor settings or plane
configuration. Holding such a crtc lock gives a read-lock on all the
other crtc state which can be changed by e.g. a modeset.

All non-crtc state is still protected by the mode_config mutex.
Callers that need to change modeset state of a crtc (e.g. dpms or
set_mode) need to grab both the mode_config lock and nested within any
crtc locks.

Note that since there can only ever be one holder of the mode_config
lock we can grab the subordinate crtc locks in any order (if we need
to grab more than one of them). Lockdep can handle such nesting with
the mutex_lock_nest_lock call correctly.

With this functions that only touch connectors/encoders but not crtcs
only need to take the mode_config lock. The biggest such case is the
output probing, which means that we can now pageflip and move cursors
while the output probe code is reading an edid.

Most cases neatly fall into the three buckets:
- Only touches connectors and similar output state and so only needs
  the mode_config lock.
- Touches the global configuration and so needs all locks.
- Only touches the crtc input side and so only needs the crtc lock.

But a few cases that need special consideration:

- Load detection which requires a crtc. The mode_config lock already
  prevents a modeset change, so we can use any unused crtc as we like
  to do load detection. The only thing to consider is that such
  temporary state changes don't leak out to userspace through ioctls
  that only take the crtc look (like a pageflip). Hence the load
  detect code needs to grab the crtc of any output pipes it touches
  (but only if it touches state used by the pageflip or cursor
  ioctls).

- Atomic pageflip when moving planes. The first case is sane hw, where
  planes have a fixed association with crtcs - nothing needs to be
  done there. More insane^Wflexible hw needs to have plane->crtc
  mapping which is separately protect with a lock that nests within
  the crtc lock. If the plane is unused we can just assign it to the
  current crtc and continue. But if a plane is already in use by
  another crtc we can't just reassign it.

  Two solution present themselves: Either go back to a slow-path which
  takes all modeset locks, potentially incure quite a hefty delay. Or
  simply disallowing such changes in one atomic pageflip - in general
  the vblanks of two crtcs are not synced, so there's no sane way to
  atomically flip such plane changes accross more than one crtc. I'd
  heavily favour the later approach, going as far as mandating it as
  part of the ABI of such a new a nuclear pageflip.

  And if we _really_ want such semantics, we can always get them by
  introducing another pageflip mutex between the mode_config.mutex and
  the individual crtc locks. Pageflips crossing more than one crtc
  would then need to take that lock first, to lock out concurrent
  multi-crtc pageflips.

- Optimized global modeset operations: We could just take the
  mode_config lock and then lazily lock all crtc which are affected by
  a modeset operation. This has the advantage that pageflip could
  continue unhampered on unaffected crtc. But if e.g. global resources
  like plls need to be reassigned and so affect unrelated crtcs we can
  still do that - nested locking works in any order.

This patch just adds the locks and takes them in drm_modeset_lock_all,
no real locking changes yet.

v2: Need to initialize the new lock in crtc_init and lock it righ
away, for otherwise the modeset_unlock_all below will try to unlock a
not-locked mutex.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      29494c17
    • D
      drm: add drm_modeset_lock|unlock_all · 84849903
      由 Daniel Vetter 提交于 
      This is the first step towards introducing the new modeset locking
scheme. The plan is to put helper functions into place at all the
right places step-by-step, so that the final patch to switch on the
new locking scheme doesn't need to touch every single driver.

This helper here will serve as the shotgun solutions for all places
where a more fine-grained locking isn't (yet) implemented.

v2: Fixup kerneldoc for unlock_all.
Reviewed-by: NRob Clark <rob@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
      84849903
  31. 20 1月, 2013 2 次提交