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?
[...]
For parallel and LVDS we'd either need to force the parallel panel to be clocked by the IPU internal clock, or move one or the other external clock source off of pll5_video.
Do you have a preference for one solution over the other?
That depends on the board. Is there an LVDS display that can be driven by a PLL other than PLL5? Since there is no sane way to change the LDB_DI parent in a running system, that should be configured in the device tree.
regards Philipp