<div dir="ltr">Hi<div> </div><div>Sorry if this is off topic, I've got a Skylake Dell laptop with a USB-C connector and no displayport </div><div> </div><div>Which USB-C -> HDMI-2.0 connector do you recommend for stuff just working based on your testing?</div><div> </div><div>I've been putting off buying one until I knew 4K@60Hz would work, CEC would be nice to have too</div><div> </div><div>Thanks</div><div> </div><div>Mike</div></div> <div class="gmail_quote"><div dir="ltr">On Thu, 25 May 2017 at 16:06 Hans Verkuil <<a href="mailto:hverkuil@xs4all.nl">hverkuil@xs4all.nl</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">From: Hans Verkuil <<a href="mailto:hans.verkuil@cisco.com" target="_blank">hans.verkuil@cisco.com</a>> This patch series adds support for the DisplayPort CEC-Tunneling-over-AUX protocol. This patch series is based on v4.12-rc2. The first four patches add support for a new CEC capability which is needed for these devices and for two helper functions. Then the DP CEC registers are added using Clint's patch. The core CEC tunneling support is added to drm_dp_cec.c. And finally this is hooked up in the i915 driver. Ideally the cec driver is created and destroyed whenever the DP-to-HDMI adapter is connected/disconnected, but I have not been a able to find a way to distinguish between connecting/disconnecting the HDMI cable and connecting/disconnecting the actual DP-to-HDMI adapter. My current approach is to check the CEC tunneling support whenever a new display is connected: - if CEC tunneling is supported, but no CEC adapter exists, then create one. - if CEC tunneling is not supported, then unregister the CEC adapter if one was created earlier. - if CEC tunneling is supported and the capabilities are identical to the existing CEC adapter, then leave it be. - if CEC tunneling is supported and the capabilities are different to the existing CEC adapter, then unregister that CEC adapter and register a new one. This works well, but it would be much nicer if I would just know when the DP adapter is disconnected as opposed to when the HDMI cable is disconnected from the adapter. Suggestions are welcome. The other remaining problem is that there are DP/USB-C to HDMI adapters that support CEC tunneling in the chipset, but where the CEC pin is simply never hooked up. From the point of view of the driver CEC is supported, but you'll never see any other devices. I am considering sending a CEC POLL message to logical address 0 (the TV) to detect if the CEC pin is connected, but this is not 100% guaranteed to work. This can be put under a kernel config option, though. I think I need to do something for this since of the 5 USB-C to HDMI adapters I've tested that set the CEC tunneling capability, only 2 have the CEC pin hooked up. So this seems to be quite common. I have tested this with my Intel NUC7i5BNK and with the two working USB-C to HDMI adapters that I have found: a Samsung EE-PW700 adapter and a Kramer ADC-U31C/HF adapter (I think that's the model, I need to confirm this). As usual the specifications of these adapters never, ever tell you whether this is supported or not :-( It's trial and error to find one that works. In fact, of the 10 USB-C to HDMI adapters I tested 5 didn't support CEC tunneling at all, and of the remaining 5 only two had the CEC pin hooked up and so actually worked. BTW, all adapters that supported CEC tunneling used the Parade PS176 chip. Output of cec-ctl -S (discovers the CEC topology): $ cec-ctl -S Driver Info: Driver Name : i915 Adapter Name : DPDDC-C Capabilities : 0x0000007e Logical Addresses Transmit Passthrough Remote Control Support Monitor All Driver version : 4.12.0 Available Logical Addresses: 4 Physical Address : 3.0.0.0 Logical Address Mask : 0x0010 CEC Version : 2.0 Vendor ID : 0x000c03 (HDMI) OSD Name : 'Playback' Logical Addresses : 1 (Allow RC Passthrough) Logical Address : 4 (Playback Device 1) Primary Device Type : Playback Logical Address Type : Playback All Device Types : Playback RC TV Profile : None Device Features : None System Information for device 0 (TV) from device 4 (Playback Device 1): CEC Version : 1.4 Physical Address : 0.0.0.0 Primary Device Type : TV Vendor ID : 0x0000f0 (Samsung) OSD Name : TV Menu Language : eng Power Status : On Topology: <a href="http://0.0.0.0" rel="noreferrer" target="_blank">0.0.0.0</a>: TV <a href="http://3.0.0.0" rel="noreferrer" target="_blank">3.0.0.0</a>: Playback Device 1 Regards, Hans Clint Taylor (1): drm/cec: Add CEC over Aux register definitions Hans Verkuil (6): cec: add CEC_CAP_NEEDS_HPD cec-ioc-adap-g-caps.rst: document CEC_CAP_NEEDS_HPD cec: add cec_s_phys_addr_from_edid helper function cec: add cec_phys_addr_invalidate() helper function drm: add support for DisplayPort CEC-Tunneling-over-AUX drm/i915: add DisplayPort CEC-Tunneling-over-AUX support .../media/uapi/cec/cec-ioc-adap-g-caps.rst | 8 + drivers/gpu/drm/Kconfig | 3 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_dp_cec.c | 196 +++++++++++++++++++++ drivers/gpu/drm/i915/Kconfig | 11 ++ drivers/gpu/drm/i915/intel_dp.c | 46 ++++- drivers/media/cec/cec-adap.c | 34 +++- drivers/media/cec/cec-api.c | 5 +- drivers/media/cec/cec-core.c | 1 + include/drm/drm_dp_helper.h | 83 +++++++++ include/media/cec.h | 15 ++ include/uapi/linux/cec.h | 2 + 12 files changed, 394 insertions(+), 11 deletions(-) create mode 100644 drivers/gpu/drm/drm_dp_cec.c -- 2.11.0 _______________________________________________ dri-devel mailing list <a href="mailto:dri-devel@lists.freedesktop.org" target="_blank">dri-devel@lists.freedesktop.org</a> <a href="https://lists.freedesktop.org/mailman/listinfo/dri-devel" rel="noreferrer" target="_blank">https://lists.freedesktop.org/mailman/listinfo/dri-devel</a> </blockquote></div>