drm: imx: multi-display support questions

[Philipp Zabel]

Hi Eric,

Am Donnerstag, den 28.05.2015, 12:30 -0700 schrieb Eric Nelson:
> Hi Philipp,
> 
> On 05/28/2015 03:58 AM, Philipp Zabel wrote:
> > Hi Gary,
> > 
> > Am Mittwoch, den 27.05.2015, 15:31 +0200 schrieb Gary Bisson:
> >>> According to the kerneldoc comment for drm_fb_helper_initial_config
> >>> (which is used by imx-drm via drm_fbdev_cma_init), it should set up a
> >>> single /dev/fb cloned over all connectors. This works here with LVDS and
> >>> HDMI.
> >>
> >> Does it require the two displays to have the exact same resolution?
> >> I'm wondering what is wrong with my setup but with a 1024x768 LVDS and
> >> a 1920x1080 HDMI display no image is shown on the HDMI (no signal).
> >> The CRTC settings show that both have the same origin (0,0) so I
> >> expected the LVDS to display a part of what the HDMI *should* display.
> > 
> > No, but it does require the HDMI and LVDS display to use different clock
> > sources (unless LVDS serializer clock happens to be the same as the HDMI
> > pixel clock).
> >
> > I wonder what we should do about this for devices that have both LVDS
> > and HDMI output and can only use PLL5 for both. Register a clock
> > notifier that vetoes changes?
> >
> 
> The LDB can be clocked from PLL2.
> 
> Here's a snippet of the clock tree from our 3.10.53 (Android) kernel
> running both HDMI at 720P and the Hannstar hsd070pww1 panel:
> 
>        pll2_pfd0_352m           1           1            500210526

What is the parent of gpu2d_core_sel? This looks like it would severely
overclock the vivante 2d core.

regards
Philipp