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  1. 23 11月, 2010 20 次提交
  3. 22 11月, 2010 2 次提交
    • M
      drm/vblank: Add support for precise vblank timestamping. · 27641c3f
      由 Mario Kleiner 提交于 
      The DRI2 swap & sync implementation needs precise
vblank counts and precise timestamps corresponding
to those vblank counts. For conformance to the OpenML
OML_sync_control extension specification the DRM
timestamp associated with a vblank count should
correspond to the start of video scanout of the first
scanline of the video frame following the vblank
interval for that vblank count.

Therefore we need to carry around precise timestamps
for vblanks. Currently the DRM and KMS drivers generate
timestamps ad-hoc via do_gettimeofday() in some
places. The resulting timestamps are sometimes not
very precise due to interrupt handling delays, they
don't conform to OML_sync_control and some are wrong,
as they aren't taken synchronized to the vblank.

This patch implements support inside the drm core
for precise and robust timestamping. It consists
of the following interrelated pieces.

1. Vblank timestamp caching:

A per-crtc ringbuffer stores the most recent vblank
timestamps corresponding to vblank counts.

The ringbuffer can be read out lock-free via the
accessor function:

struct timeval timestamp;
vblankcount = drm_vblank_count_and_time(dev, crtcid, &timestamp).

The function returns the current vblank count and
the corresponding timestamp for start of video
scanout following the vblank interval. It can be
used anywhere between enclosing drm_vblank_get(dev, crtcid)
and drm_vblank_put(dev,crtcid) statements. It is used
inside the drmWaitVblank ioctl and in the vblank event
queueing and handling. It should be used by kms drivers for
timestamping of bufferswap completion.

The timestamp ringbuffer is reinitialized each time
vblank irq's get reenabled in drm_vblank_get()/
drm_update_vblank_count(). It is invalidated when
vblank irq's get disabled.

The ringbuffer is updated inside drm_handle_vblank()
at each vblank irq.

2. Calculation of precise vblank timestamps:

drm_get_last_vbltimestamp() is used to compute the
timestamp for the end of the most recent vblank (if
inside active scanout), or the expected end of the
current vblank interval (if called inside a vblank
interval). The function calls into a new optional kms
driver entry point dev->driver->get_vblank_timestamp()
which is supposed to provide the precise timestamp.
If a kms driver doesn't implement the entry point or
if the call fails, a simple do_gettimeofday() timestamp
is returned as crude approximation of the true vblank time.

A new drm module parameter drm.timestamp_precision_usec
allows to disable high precision timestamps (if set to
zero) or to specify the maximum acceptable error in
the timestamps in microseconds.

Kms drivers could implement their get_vblank_timestamp()
function in a gpu specific way, as long as returned
timestamps conform to OML_sync_control, e.g., by use
of gpu specific hardware timestamps.

Optionally, kms drivers can simply wrap and use the new
utility function drm_calc_vbltimestamp_from_scanoutpos().
This function calls a new optional kms driver function
dev->driver->get_scanout_position() which returns the
current horizontal and vertical video scanout position
of the crtc. The scanout position together with the
drm_display_timing of the current video mode is used
to calculate elapsed time relative to start of active scanout
for the current video frame. This elapsed time is subtracted
from the current do_gettimeofday() time to get the timestamp
corresponding to start of video scanout. Currently
non-interlaced, non-doublescan video modes, with or
without panel scaling are handled correctly. Interlaced/
doublescan modes are tbd in a future patch.

3. Filtering of redundant vblank irq's and removal of
some race-conditions in the vblank irq enable/disable path:

Some gpu's (e.g., Radeon R500/R600) send spurious vblank
irq's outside the vblank if vblank irq's get reenabled.
These get detected by use of the vblank timestamps and
filtered out to avoid miscounting of vblanks.

Some race-conditions between the vblank irq enable/disable
functions, the vblank irq handler and the gpu itself (updating
its hardware vblank counter in the "wrong" moment) are
fixed inside vblank_disable_and_save() and
drm_update_vblank_count() by use of the vblank timestamps and
a new spinlock dev->vblank_time_lock.

The time until vblank irq disable is now configurable via
a new drm module parameter drm.vblankoffdelay to allow
experimentation with timeouts that are much shorter than
the current 5 seconds and should allow longer vblank off
periods for better power savings.

Followup patches will use these new functions to
implement precise timestamping for the intel and radeon
kms drivers.
Signed-off-by: NMario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>
      27641c3f
    • L
      Linux 2.6.37-rc3 · 3561d43f
      由 Linus Torvalds 提交于
      3561d43f
  5. 20 11月, 2010 13 次提交
  7. 19 11月, 2010 5 次提交
    • D
      ext4: ext4_fill_super shouldn't return 0 on corruption · 5a9ae68a
      由 Darrick J. Wong 提交于 
      At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
out of that function returns ret.  However, the generic_check_addressable
clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g.
a group checksum error) returns 0 even though the mount should fail.  This
causes vfs_kern_mount in turn to think that the mount succeeded, leading to an
oops.

A simple fix is to avoid using ret for the generic_check_addressable check,
which was last changed in commit 30ca22c7.
Signed-off-by: NDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
      5a9ae68a
    • A
      drm/i915: Disable FBC on Ironlake to save 1W · 16c59ef3
      由 Alex Shi 提交于 
      Frame buffer compression is broken on Ironlake due to buggy hardware.
Currently it is disabled through chicken bits, but it still consumes
over 1W more than if we simply never attempt to enable the FBC code
paths.
Signed-off-by: NAlex Shi <alex.shi@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
      16c59ef3
    • K
      drm/i915: Take advantage of auto-polling CRT hotplug detection on PCH hardware · e7dbb2f2
      由 Keith Packard 提交于 
      Both IBX and CPT have an automatic hotplug detection mode which appears to work reliably enough
that we can dispense with the manual force hotplug trigger stuff. This means that
hotplug detection is as simple as reading the current hotplug register values.

The first time the hotplug detection is activated, the code synchronously waits for a hotplug
sequence in case the hardware hasn't bothered to do a detection cycle since being initialized.
Signed-off-by: NKeith Packard <keithp@keithp.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
      e7dbb2f2
    • C
      drm/i915/crt: Introduce struct intel_crt · c9a1c4cd
      由 Chris Wilson 提交于 
      We will use this structure in future patches to store CRT specific
information on the encoder.

Split out and tweaked from a patch by Keith Packard.
Signed-off-by: NKeith Packard <keithp@kithp.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
      c9a1c4cd
    • C
      drm/i915: Do not hold mutex when faulting in user addresses · 51311d0a
      由 Chris Wilson 提交于 
      Linus Torvalds found that it was rather trivial to trigger a system
freeze:

  In fact, with lockdep, I don't even need to do the sysrq-d thing: it
  shows the bug as it happens. It's the X server taking the same lock
  recursively.

  Here's the problem:

    =============================================
    [ INFO: possible recursive locking detected ]
    2.6.37-rc2-00012-gbdbd01ac #7
    ---------------------------------------------
    Xorg/2816 is trying to acquire lock:
     (&dev->struct_mutex){+.+.+.}, at: [<ffffffff812c626c>] i915_gem_fault+0x50/0x17e

    but task is already holding lock:
     (&dev->struct_mutex){+.+.+.}, at: [<ffffffff812c403b>] i915_mutex_lock_interruptible+0x28/0x4a

    other info that might help us debug this:
    2 locks held by Xorg/2816:
     #0:  (&dev->struct_mutex){+.+.+.}, at: [<ffffffff812c403b>] i915_mutex_lock_interruptible+0x28/0x4a
     #1:  (&mm->mmap_sem){++++++}, at: [<ffffffff81022d4f>] page_fault+0x156/0x37b

This recursion was introduced by rearranging the locking to avoid the
double locking on the fast path (4f27b5d and fbd5a26d) and the
introduction of the prefault to encourage the fast paths (b5e4f2b). In
order to undo the problem, we rearrange the code to perform the access
validation upfront, attempt to prefault and then fight for control of the
mutex.  the best case scenario where the mutex is uncontended the
prefaulting is not wasted.
Reported-and-tested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
      51311d0a