It looks like 'after a while', I915REG_INT_IDENTITY_R for some reason always has
VSYNC_PIPEB_FLAG set in the interrupt handler, even though pipe B is disabled.
So we only increase dev->vbl_received if the corresponding bit is also set in
dev->vblank_pipe.
Initialize it to default value if it hasn't been set by the X server yet.
In i915_vblank_pipe_set(), only update dev_priv->vblank_pipe and call
i915_enable_interrupt() if the argument passed from userspace is valid to avoid
corrupting dev_priv->vblank_pipe on invalid arguments.
Handle relative as well as absolute target sequence numbers.
Return error if target sequence has already passed, so userspace can deal with
this situation as it sees fit.
On success, return the sequence number of the vertical blank when the buffer
swap is expected to take place.
Also add DRM_IOCTL_I915_VBLANK_SWAP definition for userspace code that may want
to use ioctl() instead of drmCommandWriteRead().
When the vertical blank interrupt is enabled for both pipes, pipe A is
considered primary and pipe B secondary. When it's only enabled for one pipe,
it's always considered primary for backwards compatibility.
i915 vblanks can be generated from either pipe a or b, however a disabled
pipe generates no interrupts. This change allows the X server to select
which pipe generates vblank interrupts.
that particular file. Its contents have changed a good bit since the
original sis code, and the original sis code didn't care much about
attribution since it routinely disclaims Precision Insight/VA Linux
from responsibility. Also, adjust formatting around license headers
(have a comment open immediately before the "Copyright" line, not as a
runon of any previous comments) for automatic processing into FreeBSD,
where /*- is used to signal the beginning of license headers for
automatic compilation of license lists.
Michel Dänzer
Dave Airlie
Alan Hourihane
Keith Packard
Keith Whitwell
Eric Anholt
Alan Hourihane
Jon Smirl