[BUG] drm: rockchip: vop_crtc_mode_fixup is breaking clock configuration

[Vicente Bergas]

I've recently installed U-boot to boot a Sapphire board with the HDMI 
display, before i was using Linux + kexec as bootloader.
Since then, linux fails to re-initialize the HDMI display giving the 
following error message:
dwhdmi-rockchip ff940000.hdmi: PHY configuration failed (clock 148501000)
which comes from drivers/gpu/drm/bridge/synopsys/dw-hdmi.c:1522

The clock frequency 148500000 is 'rounded up' to 148501000 in 
vop_crtc_mode_fixup from which comes from 
drivers/gpu/drm/rockchip/rockchip_drm_vop.c:1184

So far i've found two workarounds: remove the vop_crtc_mode_fixup function 
or unplug and reconnect the HDMI cable.
>From my point of view, not having a display is a regression, although not 
in Linux itself, is in its environment.

U-boot is configuring the display at 2560x1440, which proves the HW is 
capable of running at such resolution.
Linux instead is configuring it at 1920x1080, resolutions above that are 
not even supported.
Please, can this situation be improved?

Any feedback is welcome and i am willing to help!

Regards,
  Vicente.