47b1be5c0f
If the bootloader already enabled the display, the interrupt handler will be called as soon as it is registered. If the CRTC is not already added at this time, the call to imx_drm_handle_vblank will result in a NULL pointer dereference. The patch fixes a kernel panic [1], which has been on linux-next since Jan 8 [2]. [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/218858 [2] http://thread.gmane.org/gmane.linux.ports.arm.kernel/208192 Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Tested-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>