Do not clear interrupt mask upon interrupt.
Instead clear pending interrupt status and write
QXL_IO_UPDATE_IRQ register (this drops interrupt level).
There are 3 advantages:
1. We do not need to wake the host to enable interrupt
mask in DPC procedure (1 wake per interrupt instead of 2)
2. The driver is not sensitive to failure when queues DPC, as
already queued DPC will process this interrupt when executed.
3. When we implement VSync interrupt simulation, we do not
need to touch registers neither when notify the OS nor when
process DPC related to this notification.
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Acked-by: Frediano Ziglio <fziglio@redhat.com>
a2b58d1557