drm/i915: make semaphore signaller detection more robust
Extract all this logic into a new helper function
semaphore_wait_to_signaller_ring because:
- The current code has way too much magic.
- The current code doesn't look at bi16, which encodes VECS signallers
on HSW. Those are just added after the fact, so can't be encoded in
a neat formula.
- The current logic can't blow up since it limits its value range
sufficiently, but that's a bit too tricky to rely on in my opinion.
Especially when we start to add bdw support.
- I'm not a big fan of the explicit ring->semaphore_register list, but
I think it's more robust to use the same mapping both when
constructing the semaphore commands and when decoding them.
- Finally add a FIXME comment about lack of broadwell support here,
like in the earlier ipehr semaphore cmd detection function.
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
[danvet: Actually drop the untrue claim in the commit message Chris
pointed out.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed