[Intel-gfx] [RFC] drm: implement DRM_IOCTL_MODE_SETROTATION

Paulo Zanoni przanoni at gmail.com
Mon Jan 16 21:50:27 CET 2012

2012/1/16 Dave Airlie <airlied at gmail.com>:
> Okay I must have missed the bit where you explain why a connector
> property isn't used?

The registers that contain the rotation information are the pipe
registers and, as far as I understood, each pipe is associated with
only one crtc. We can have more than one connector associated with one
crtc. So, in a case where we have two different connectors associated
with the same crtc, we would have to keep synchronizing the property
value between the two connectors: this doesn't sound like the best
solution and it could also create confusion (imagine the case where
connectors A and B are associated with the same crtc, and you set
connector_a.rotation to 0 and then connector_b.rotation to 180, then
you'll read connector_a.rotation and it will be 180, not what you just

(and by the way, the three patches were sent just to dri-devel@)

Paulo Zanoni

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