It would be nice if one day the DRM driver was the canonical source for
register definitions and core macros. To that end, this patch cleans things up
quite a bit, removing redundant definitions (some with different names
referring to the same register) and generally tidying up the header file.
Without kernel modesetting, this requires cooperation of the userspace
modesetting driver. We may have to leave the vblank interrupt enabled otherwise
to avoid problems.
Only compensate when the driver counter actually appears to have moved
backwards.
The compensation deltas need to be incremental instead of absolute; drop the
vblank_offset field and just use atomic_sub().
Turns out the radeon driver is affected by the same problem that prompted i915
to revert to less useful counter flipping at the end of the vblank interval. In
the long term, we can hopefully implement more reliable methods to achieve
counter flipping at the beginning of vblank, but otherwise this should be an
acceptable workaround.
This reverts commit 6671ad1917.
The vblank ioctl needs to update the userspace parameters when interrupted by
a signal, which was prevented by this. Let's see if this breaks other ioctls...
The kernel has removed nopage so move the old nopage codepaths into a compat vm file and switch to using the fault paths.
nopfn is on its way out in the future also, so we should switch to using fault
for that path as well soon
This tries to automatically fetch a git revision string and if succeeds,
it #defines GIT_REVISION string macro. Packagers can override it by
'make GIT_REVISION=foo'.
Update Nouveau to use GIT_REVISION, if defined, instead of DRIVER_DATE
in struct drm_driver.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
This is the correct fix for the RS690 and hopefully the dma coherent work.
For now we limit everybody to a 32-bit DMA mask but it is possible for
RS690 to use a 40-bit DMA mask for the GART table itself,
and the PCIE cards can use 40-bits for the table entries.
Signed-off-by: Dave Airlie <airlied@redhat.com>
The i915_vblank_swap() function schedules an automatic buffer swap
upon receipt of the vertical sync interrupt. Such an operation is
lengthy so it can't be allowed to happen in normal interrupt context,
thus the DRM implements this by scheduling the work in a kernel
softirq-scheduled tasklet. In order for the buffer swap to work
safely, the DRM's central lock must be taken, via a call to
drm_lock_take() located in drivers/char/drm/drm_irq.c within the
function drm_locked_tasklet_func(). The lock-taking logic uses a
non-interrupt-blocking spinlock to implement the manipulations needed
to take the lock. This semantic would be safe if all attempts to use
the spinlock only happen from process context. However this buffer
swap happens from softirq context which is really a form of interrupt
context. Thus we have an unsafe situation, in that
drm_locked_tasklet_func() can block on a spinlock already taken by a
thread in process context which will never get scheduled again because
of the blocked softirq tasklet. This wedges the kernel hard.
To trigger this bug, run a dual-head cloned mode configuration which
uses the i915 drm, then execute an opengl application which
synchronizes buffer swaps against the vertical sync interrupt. In my
testing, a lockup always results after running anywhere from 5 minutes
to an hour and a half. I believe dual-head is needed to really
trigger the problem because then the vertical sync interrupt handling
is no longer predictable (due to being interrupt-sourced from two
different heads running at different speeds). This raises the
probability of the tasklet trying to run while the userspace DRI is
doing things to the GPU (and manipulating the DRM lock).
The fix is to change the relevant spinlock semantics to be the
interrupt-blocking form. After this change I am no longer able to
trigger the lockup; the longest test run so far was 20 hours (test
stopped after that point).
Note: I have examined the places where this spinlock is being
employed; all are reasonably short bounded sequences and should be
suitable for interrupts being blocked without impacting overall kernel
interrupt response latency.
Signed-off-by: Mike Isely <isely@pobox.com>
