AGL on RPi3 fails to sync preferred mode on many HDMI displays
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Leon Anavi July 11, 2017 at 2:00 PM
Hi,
I build AGL from the master branch for Raspberry Pi 3. Although the kernel is still 4.4.50 I have not detected any issues on the HDMI monitors that I have around here. As of the moment the configurations in weston.ini are:
My conclusion is that the issue has been fixed.
Best regards,
Leon
Leon Anavi June 7, 2017 at 9:33 PM
Hi Walt,
No idea. Testing is blocked by the blank screen issue in the current AGL master for Raspberry Pi 3: https://lf-automotivelinux.atlassian.net/browse/SPEC-650
Best regards,
Leon
Walt Miner June 7, 2017 at 9:26 PM
Is this still an issue for Dab?
Jan-Simon Moeller April 18, 2017 at 11:19 AM
Is this still an issue ?
Jan-Simon Moeller January 16, 2017 at 2:14 PM
Update kernel/drivers in chinook in a point-update ?
Master (morty) is also on 4.4 still, but might move to 4.8 based on how meta-raspberrypi looks like atm.
Builds from master for RPi3 contain a downstream RPi kernel version 4.4.16. The vc4 drm we are using in this kernel does detect a connected display (actually this is hacked up a bit and doesn't use the gpio based detect on RPi3) and properly reads EDID, and selects a preferred mode (e.g. 60hz 1080p) from those presented. However, setting this mode results in an "out of range" warning on the monitor if this bug is hit.
I verified that this issue occurs on 3 different displays I have handy (which work on other boards like Minnowboard Max/Turbot) including the GeChic 1080p display we have speced for the CES 2017 demos, a Hisense TV, and a Sceptre monitor.
Meanwhile, if I run the upstream stable 4.8 kernel (only patched similarly to the downstream hack to deal with lack of gpio detect of a connected display), these same monitors are all able to sync the select 60hz 1080p mode that's selected by the drm subsystem.
My initial review of the downstream versus upstream driver doesn't show any obvious patches we're missing to address this issue. The upstream driver is quite a bit different now with some major timing related changes. It may be possible to backport this.
A short-term alternative to make the RPi3 build usable with the CES 2017 GeChic display is to hardcode the mode or a specific modeline for the GeChic monitor. Simply adding:
[output]
name=HDMI-A-1
mode=1024x768
to weston.ini was enough for the vc4 drm driver to sync a mode on the GeChic display. It's also possible to specify a complete modeline. Not a great workaround but something usable for a demo. This overrides the default behavior of Weston to use the current mode which will generally be the preferred mode that the vc4 drm driver selects by default (which, with this driver is broken depending on the monitor).