Hi Sorry if this is off topic, I've got a Skylake Dell laptop with a USB-C connector and no displayport
Which USB-C -> HDMI-2.0 connector do you recommend for stuff just working based on your testing? I've been putting off buying one until I knew 4K@60Hz would work, CEC would be nice to have too Thanks Mike On Thu, 25 May 2017 at 16:06 Hans Verkuil <hverk...@xs4all.nl> wrote: > From: Hans Verkuil <hans.verk...@cisco.com> > > 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: > > 0.0.0.0: TV > 3.0.0.0: 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 > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel >
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