On 06/01/2017 10:31 AM, Hans Verkuil wrote:
Hi Russell,
First a few top-level questions:
1) What was the reason for using the cec-notifier here? Isn't this
tightly integrated into the main dw-hdmi block? For the tda driver
it is clearly required, but for tightly coupled HDMI & CEC HW I
just create the adapter from the HDMI driver. As a small bonus it
avoids adding the cec-notifier code and the control flow is a bit
easier to trace.
2) I may have asked this before, apologies if I repeat myself: does
this CEC implementation support CEC monitoring (aka snooping)? If
it does, then I recommend that it is implemented since it is very
useful.
3) Is the CEC still active if there is no hotplug signal? Or is it
powered off in that case? Ideally it should still be possible to
send CEC messages even if there is no hotplug. This is explicitly
allowed by the CEC 2.0 spec to wake up displays that turn off the
HPD, but that still have a working CEC controller.
If this is not possible, then you need to use the CEC_CAP_NEEDS_HPD
capability. See: https://patchwork.linuxtv.org/patch/41478/
This will almost certainly be merged for 4.13 since other CEC drivers
need this as well.
FYI: I tested your patch series with my cubox-i and CEC doesn't work if there
is no HPD. I fiddles around a bit in dw_hdmi.c to prevent it from powering off
the HDMI and PHY, but without any luck. It could be a hardware issue on the
cubox-i (e.g. a level-shifter that powers off when the HPD goes low, although
I don't see anything like that in the schematics), or it can be a driver issue
or a Synopsys IP issue. I really can't tell.
I added text in my status document (https://hverkuil.home.xs4all.nl/cec-status.txt)
at the end on how to test this.
Otherwise the CEC support on the cubox-i was working very well.
Regards,
Hans
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