On 05/30/2017 02:29 PM, Hans Verkuil wrote:
On 05/30/2017 10:32 PM, Clint Taylor wrote:
On 05/30/2017 09:54 AM, Hans Verkuil wrote:
On 05/30/2017 06:49 PM, Hans Verkuil wrote:
On 05/30/2017 04:19 PM, Clint Taylor wrote:
On 05/30/2017 12:11 AM, Jani Nikula wrote:
On Tue, 30 May 2017, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
On 05/29/2017 09:00 PM, Daniel Vetter wrote:
On Fri, May 26, 2017 at 12:20:48PM +0200, Hans Verkuil wrote:
On 05/26/2017 09:15 AM, Daniel Vetter wrote:
Did you look into also wiring this up for dp mst chains?
Isn't this sufficient? I have no way of testing mst chains.
I think I need some pointers from you, since I am a complete
newbie when it
comes to mst.
I don't really have more clue, but yeah if you don't have an mst
thing (a
simple dp port multiplexer is what I use for testing here, then
plug in a
converter dongle or cable into that) then probably better to not
wire up
the code for it.
I think my NUC already uses mst internally. But I was planning on
buying a
dp multiplexer to make sure there is nothing special I need to do
for mst.
The CEC Tunneling is all in the branch device, so if I understand
things
correctly it is not affected by mst.
BTW, I did a bit more testing on my NUC7i5BNK: for the HDMI output
they
use a MegaChip MCDP2800 DP-to-HDMI converter which according to
their
datasheet is supposed to implement CEC Tunneling, but if they do
it is not
exposed as a capability. I'm not sure if it is a MegaChip firmware
issue
or something else. The BIOS is able to do some CEC, but whether
they hook
into the MegaChip or have the CEC pin connected to a GPIO or
something and
have their own controller is something I do not know.
If anyone can clarify what Intel did on the NUC, then that would
be very
helpful.
It's called LSPCON, see i915/intel_lspcon.c, basically to support
HDMI
2.0. Currently we only use it in PCON mode, shows up as DP for
us. It
could be used in LS mode, showing up as HDMI 1.4, but we don't
support
that in i915.
I don't know about the CEC on that.
My NUC6i7KYK has the MCDP2850 LSPCON and it does support CEC over
Aux.
The release notes for the NUC state that there is a BIOS
configuration
option for enabling support. My doesn't have the option but the
LSPCON
fully supports CEC.
What is the output of:
dd if=/dev/drm_dp_aux0 of=aux0 skip=12288 ibs=1 count=48
od -t x1 aux0
Assuming drm_dp_aux0 is the aux channel for the HDMI output on your
NUC.
If the first byte is != 0x00, then it advertises CEC over Aux.
For me it says 0x00.
When you say "it does support CEC over Aux", does that mean you have
actually
tested it somehow? The only working solution I have seen mentioned
for the
NUC6i7KYK is a Pulse-Eight adapter.
With the NUC7i Intel made BIOS support for CEC, but it is not at all
clear to me if they used CEC tunneling or just hooked up the CEC
pin to
some microcontroller.
The only working chipset I have seen is the Parade PS176.
If it really is working on your NUC, then can you add the output of
/sys/kernel/debug/dri/0/i915_display_info?
[root@localhost cec-ctl]# cat /sys/kernel/debug/dri/0/i915_display_info
Connector info
--------------
connector 48: type DP-1, status: connected
name:
physical dimensions: 700x400mm
subpixel order: Unknown
CEA rev: 3
DPCD rev: 12
audio support: yes
DP branch device present: yes
Type: HDMI
ID: 175IB0
HW: 1.0
SW: 7.32
Max TMDS clock: 600000 kHz
Max bpc: 12
Huh. Based on this document:
https://downloadmirror.intel.com/26061/eng/NUC6i7KYK%20HDMI%202.0%20Firmware%20update%20Instructions.pdf
this is the internal DP-to-HDMI adapter and it has the PS175. So it is a
Parade chipset, and I have seen that work before (at least the PS176).
This is the PS175 LSPCON on the NUC6.
<snip>
connector 55: type DP-2, status: connected
name:
physical dimensions: 620x340mm
subpixel order: Unknown
CEA rev: 3
DPCD rev: 12
audio support: yes
DP branch device present: yes
Type: HDMI
ID: BCTRC0
HW: 2.0
SW: 0.26
And is this from a USB-C to HDMI adapter? Which one? I don't recognize
the ID.
This is a LSPCON inside the Google USB-C->HDMI dongle. This is actually
a MC2850 with what appears to be a custom ID. Datasheet claims CEC over
Aux and the pin is wired, but FW has it currently disabled.
-Clint
For the record, this is the internal HDMI output of my NUC7i5BNK:
connector 48: type DP-1, status: connected
name:
physical dimensions: 1050x590mm
subpixel order: Unknown
CEA rev: 3
DPCD rev: 12
audio support: yes
DP branch device present: yes
Type: HDMI
ID: MC2800
HW: 2.2
SW: 1.66
Max TMDS clock: 600000 kHz
Max bpc: 16
Clearly a Megachip.
Regards,
Hans
