(In reply to iuno from comment #59)

> 
> @withoutaface: You have to rebuild your kernel. ...

I rebuild my kernel 4.10.0-22 (ubuntu 17.04) and patched radeon driver 
(atombios_crtc.c)
void radeon_atom_disp_eng_pll_init(struct radeon_device *rdev)
{
        /* always set DCPLL */
rdev->clock.default_dispclk = 62500;
        if (ASIC_IS_DCE6(rdev))
...

144Hz is working fine with this patch. 
(Forcing dpm state high = perfect image / low or auto = bad flickering) 
But Great improvement so far! Thank you.