On Mon, Jun 9, 2014 at 11:33 AM, Shawn Guo shawn.guo@freescale.com wrote:
On Mon, Jun 09, 2014 at 11:29:28AM -0300, Fabio Estevam wrote:
On Mon, Jun 9, 2014 at 11:06 AM, Russell King - ARM Linux linux@arm.linux.org.uk wrote:
Please check the status in /sys/class/drm/card0-HDMI-A-1/status. This should report the current state of the hotplug detection.
/sys/class/drm/card0-HDMI-A-1/status returns the correct state for HDMI cable connection.
Remember that this code detects off the HPD signal - if the HPD signal has not been correctly wired up, this patch is not going to help (really it comes down to a hardware fault, which I'm not trying to solve with this patch.)
What I'm trying to resolve with this patch is that the state detected on properly wired up systems corresponds with the real initial state of the interface at initialisation time.
The problem with the current code is that we start off assuming that the interface is disconnected, and we rely on an interrupt arriving to change that state. If for whatever reason that interrupt does not arrive, then, even if the HPD signal is active, we continue believing that the interface is not connected.
I seem to remember discussion in the past that the HPD signal is not wired up on SabreSD. Really, this needs to be a DT flag to indicate
It is sabrelite board that does not have HPD signal not wired up.
sabresd does have HPD signal connected.
The HDMI undetected issue I am seeing on sabresd seems to be related to the simultaneous usage of HDMI and LVDS.
If I remove the ldb node from the imx6qdl-sabresd.dtsi, then the HDMI cable is correctly detected and HDMI is shown right after boot.
This is a known limitation.
http://thread.gmane.org/gmane.linux.ports.arm.kernel/315968/focus=318559
There were versions of linux-next that hdmi and lvds works at the same time without problems.