The newbus lock is responsible for protecting newbus internIal structures,
device states and devclass flags. It is necessary to hold it when all
such datas are accessed. For the other operations, softc locking should
ensure enough protection to avoid races.
Newbus lock is automatically held when virtual operations on the device
and bus are invoked when loading the driver or when the suspend/resume
take place. For other 'spourious' operations trying to access/modify
the newbus topology, newbus lock needs to be automatically acquired and
dropped.
For the moment Giant is also acquired in some key point (modules subsystem)
in order to avoid problems before the 8.0 release as module handlers could
make assumptions about it. This Giant locking should go just after
the release happens.
Please keep in mind that the public interface can be expanded in order
to provide more support, if there are really necessities at some point
and also some bugs could arise as long as the patch needs a bit of
further testing.
Bump __FreeBSD_version in order to reflect the newbus lock introduction.
Reviewed by: ed, hps, jhb, imp, mav, scottl
No answer by: ariff, thompsa, yongari
Tested by: pho,
G. Trematerra <giovanni dot trematerra at gmail dot com>,
Brandon Gooch <jamesbrandongooch at gmail dot com>
Sponsored by: Yahoo! Incorporated
Approved by: re (ksmith)
The Intel 2d driver calls modeset before reinstalling the handler on
a vt switch. This means that vblank status ends up getting cleared
after it has been setup. Restore saved values for the pipestat registers
rather than just wiping them out.
MFC after: 3 days
Use the vbl_lock when maniputlating the refcount. Eventually I want to
convert this to use our internal refcount code. Continue to use atomic
ops for manipulating vblank count since we access it often just for
reading.
MFC after: 3 days
Intel agrees with my reading of the docs, make it so for all G4X chips.
The new register also has a 32 bit width as opposed to 24 bits. Fix
things up so that the counters roll over properly.
MFC after: 3 days
When a vt switch occurs the irq handler is uninstalled. Interrupts
and the state tracking of what was enabled/disabled wasn't working
properly. This should resolve the reports of "slow windows" after a
vt switch, among other things. The radeon 2d driver seems to work a
bit more correctly than the Intel driver. With the Intel driver,
vblank interrupts will be enabled at system startup and will only
be disabled after an additional modeset (vt switch, dpms, randr event).
With this patch, I am able to run glxgears synced to vblank and
vt switch while it is running without ill effects.
MFC after: 3 days
after vt switch or suspend. I can't really test this on Intel right now
but I think I've heard reports of it on radeon as well. I can't break
it on the radeon here.
MFC after: 3 days
