linux/drivers/gpu
Oscar Mateo 72c90f625c drm/i915: Ack interrupts before handling them (GEN5 - GEN7)
Otherwise, we might receive a new interrupt before we have time to ack the first
one, eventually missing it.

According to BSPec, the right order should be:

1 - Disable Master Interrupt Control.
2 - Find the source(s) of the interrupt.
3 - Clear the Interrupt Identity bits (IIR).
4 - Process the interrupt(s) that had bits set in the IIRs.
5 - Re-enable Master Interrupt Control.

Without an atomic XCHG operation with mmio space, the above merely reduces the window
in which we can miss an interrupt (especially when you consider how heavyweight the
I915_READ/I915_WRITE operations are).

We maintain the "disable SDE interrupts when handling" hack since apparently it works.

Spotted by Bob Beckett <robert.beckett@intel.com>.

v2: Add warning to commit message and comments to the code as per Chris Wilson's request.
v3: Improve the source comments.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-06-18 00:48:37 +02:00
..
drm drm/i915: Ack interrupts before handling them (GEN5 - GEN7) 2014-06-18 00:48:37 +02:00
host1x gpu: host1x: Rename internal functions for clarity 2014-06-05 23:10:30 +02:00
ipu-v3 gpu: ipu-v3: Register the CSI modules 2014-06-04 11:07:12 +02:00
vga vgaswitcheroo: switch the mux to the igp on power down when runpm is enabled 2014-06-02 10:25:08 -04:00
Makefile gpu: ipu-v3: Move i.MX IPUv3 core driver out of staging 2014-06-04 11:06:52 +02:00