On 05/31/17 14:04, Marek Szyprowski wrote:
> Hi Hans,
>
> On 2017-05-31 13:17, Hans Verkuil wrote:
>> On 05/31/17 13:00, Marek Szyprowski wrote:
>>> Exynos5250 and Exynos542x SoCs have the same CEC hardware module as
>>> Exynos4 SoC series, so enable support for it using the same compatible
>>> string.
>>>
>>> Tested on Odroid XU3 (Exynos5422) and Google Snow (Exynos5250) boards.
>> Thanks!
>>
>> Do you know if the CEC block is always on for these devices or only if there
>> is a hotplug signal? That was a problem with the exynos4 odroid.
>
> Odroid XU3 has exactly same wiring between SoC & HDMI connector (via
> IP4791CZ12
> chip) as Odroid U3, so I expect the same issues.
>
> I don't have schematic for Google Snow board, so I have no idea how it works
> there.
>
>> I have made a patch (not posted yet) to signal this in the device tree and
>> added a CEC capability to signal this to the user.
>>
>> This capability will be added to 4.13 (see my patch 'cec: add
>> CEC_CAP_NEEDS_HPD'
>> from May 25th) since the DisplayPort CEC tunneling feature needs it as well.
>>
>> It's easy to test: don't connect an HDMI cable and run:
>>
>> cec-ctl --playback
>> cec-ctl -t0 --image-view-on
>>
>> If this returns with a NACK error, then it is OK. If you get a kernel message
>> that the transmit timed out, then you need this capability since CEC is
>> disabled
>> without HPD.
>
> I've checked those commands, but on all tested boards (Odroid U3+,
> Odroid XU3 and
> Google Snow) I get the following message:
>
> Transmit from Unregistered to TV (255 to 0):
> CEC_MSG_IMAGE_VIEW_ON (0x04)
> Sequence: 19 Tx Timestamp: 175.935s
> Tx, Error (1), Max Retries
>
> I have never got a timeout message from the kernel. Do I need to enable
> some kind
> of CEC debugs?
Ah, that's right. CEC works, but the level shifter drops the CEC signal
when there is no HPD. So this is actually quite hard to test.
The easiest is to get a Pulse-Eight USB CEC adapter since then you can
connect the odroid to the Pulse-Eight without connecting that to a TV
in turn. Sending a CEC command would show up with the Pulse-Eight if CEC
works without HPD.
Regards,
Hans
