Hello,

When rotating X's display on the fly using xrandr -o left|normal|inverted|right command, following transitions are performed with black screen delay effect i.e. the display becomes black for a moment then displays rotated screen.

The following transitions are performed with a delay - a black screen is shown with ~1 second duration, then rotated screen appears
normal > right|left 
inverted > normal|left|right
left > normal|inverted
right > normal|inverted

The following transitions are performed smoothly with no delays, i.e. "immediately"
normal > inverted
left > right
right > left


Steps to reproduce
1. Run following on machine with xorg-x11-drv-intel 
2. In terminal run following from normal orientation : xrandr -o left

Actual result : 
Screen is rotated with delay and black screen effect then it shows normal rotated screen

Expected result : 
Should rotate screen with no delays and any black screen effect. 
Like when rotating from the right orientation to the left orientation.



Details : Most time consuming code while rotating the display orientation with xrandr is 
ret = crtc->funcs->set_mode_major(crtc, mode, rotation, x, y); 
intel video drivers function call.
This call is located in hw/xfree86/modes/xf86Crtc.c file in xf86CrtcSetModeTransform function.

HW Platforms:
Graphics : Intel GMA 3150 graphics
Graphics : Intel Graphics Media Accelerator (GMA) 950

Xorg-server 1:7.5
xserver-xorg-video-intel 2:2.11.0
xserver-xorg-video-intel 2:2.12.0
xserver-xorg-video-intel 2:2.13.0


Regards,
Levon