[PATCH] drm/radeon/kms: add query for crtc hw id from crtc id to get info

[Lucas Clemente Vella]

 On regarding this bug
https://bugs.freedesktop.org/show_bug.cgi?id=29726
what is the relation between querying crtc id and the vblank event?
Could you point where this query is needed?

-- 
Lucas Clemente Vella
lvella at gmail.com