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Many HDMI CEC Drivers Being Written For Linux

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  • Many HDMI CEC Drivers Being Written For Linux

    Phoronix: Many HDMI CEC Drivers Being Written For Linux

    The Linux state for HDMI CEC (Consumer Electronics Control) continues to improve and several drivers are in the works...

    http://www.phoronix.com/scan.php?pag...CEC-2017-State

  • #2
    I hope this finally will make CEC a good working thing. And that interest in getting a compliant and correct working CEC gets hot.
    And that finally it will mean that PC's finally get CEC support by default, instead of a CEC crippling experience.

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    • #3
      Originally posted by Ardje View Post
      I hope this finally will make CEC a good working thing. And that interest in getting a compliant and correct working CEC gets hot.
      And that finally it will mean that PC's finally get CEC support by default, instead of a CEC crippling experience.
      Don't get your hopes too high. Nvidia has gone on record saying that GeForce hardware cannot do CEC due to an intrinsic hardware limitation (something about how the card's outputs are controlled). I do not know about Radeons/APUs or the graphics chips in Intel CPUs but I don't expect much different.

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      • #4
        Two questions:

        - Could AMD put the hardware required for CEC in its next GPUs if not present in the current ones? I can't imagine it being *that* hard to implement
        - Could we make something similar for Display Port?

        As far as I know, we can transmit any packet we want with Display Port; but there is currently no standard for CEC-Like functionality. Some can say "Just transmit USB HID packets", but while that could be great, that's waay overkill, and unadapted for messages such as "Playback stopped/Resumed", or "Device turned on", etc. Some standard would be welcome Edit: strike that. I didn't see the bit on the DP forwarding RFC. That's great (although I might have used the occasion for some cleanup in the spec, but I didn't read the RFC *yet*).

        Btw, is there any way of transmitting power over a display port connector? Edit: looks like I'm answering myself a lot today. DPDP_PWR seems to do that, but I don't know if it is widely used.

        (USB 3.1 will save us all. on paper, at least)
        Last edited by [email protected]; 05-30-2017, 02:31 PM.

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        • #5
          Originally posted by roothorick View Post

          Don't get your hopes too high. Nvidia has gone on record saying that GeForce hardware cannot do CEC due to an intrinsic hardware limitation (something about how the card's outputs are controlled). I do not know about Radeons/APUs or the graphics chips in Intel CPUs but I don't expect much different.
          I doubt that hardware limitation is severe since you can always use the Pulse-eight dongle between the GPU and the TV/receiver. They just don't want to support it. NVIDIA's mobile platform supports HDMI CEC, so do many ARM boards.

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          • #6
            Originally posted by caligula View Post

            I doubt that hardware limitation is severe
            the physical layer is really simple, you could implement this with an edge-triggerable gpio pin and a 1.2ms timer. Maybe there's licensing costs nvidia just doesn't
            want to pay for their desktop parts?

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            • #7
              CEC has been nothing short of magic on my Raspberry Pi running OSMC. May it live long and prosper.

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              • #8
                USB CEC adapters, USB CEC adapters for everyone. https://www.amazon.com/Pulse-Eight-P.../dp/B005JU6LWM

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                • #9
                  Originally posted by roothorick View Post
                  Don't get your hopes too high. Nvidia has gone on record saying that GeForce hardware cannot do CEC due to an intrinsic hardware limitation (something about how the card's outputs are controlled). I do not know about Radeons/APUs or the graphics chips in Intel CPUs but I don't expect much different.
                  The problem with a lot of pc hardware is that they are short-circuiting the CEC pin. That's why you can buy a special cable to connect a pc to a tv.
                  CEC is just an open-collector bus talking rs232 protocol. If you short circuit it on any of the tv inputs, CEC on all inputs is dead. It's really not hard to implement a serial chip behind. It certainly isn't hard to just leave it unconnected. Maybe they do leave it open now. I think intel even routes it to some connector so you can attach an after-market serdes inside the system.
                  But currently I am not aware on any PC based system, except for consoles, that support or just ignore CEC.

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