+People in community.
Rodrigo,
Thanks for the kind info.
What's the answer to below question?
I find i915 binds one pipeline per display. It means even with DP1.2 MST, i915 driver still restricts the display number to the display pipeline number. Am I right?
In addition, I might mislead you at case 1). The NUC has 1 HDMI interface and 1 USB type-C interface. I connect a display by HDMI to that HDMI interface. Then, I connect other 2 displays by the CE-LINK box which connect to the usb type-C interface.
Yanmin
-----Original Message----- From: Vivi, Rodrigo Sent: Tuesday, December 04, 2018 6:28 AM To: Zhang, Yanmin yanmin.zhang@intel.com Cc: Syrjala, Ville ville.syrjala@intel.com Subject: Re: DP1.2 MST HUB
Hi there,
again, please ask these questions in public mailing lists.
On Sun, Dec 02, 2018 at 06:43:31PM -0800, Zhang, Yanmin wrote:
Here is the result.
- If I use a CE-LINK 1-to-2 converter, 1usb type-C in, and 2 HDMI out, it works
with my NUC. This NUC has 1 HDMI and 1 USB type C interfaces.
a) If I connect 1 display by HDMI, and other 2 displays by the CE-LINK,
android refuses (logcat shows No permission) to show application GUI to the 3rd display. It might be an issue of Android.
b) If I remove HDMI display, but just connect other 2 displays by CE-LINK,
both displays can work.
- If I use CLUB-3D box which has 1 DP in and 4 DP out, I have to use a usb type-
C to DP cable, then connect to a DP converter with 2 daughter interfaces, then connect to the CLUB-3D, then to 2 displays. Kernel driver reports the displays, but the display is always black. Perhaps there are too many converters on the connection path.
If I use CLUB-3D box to connect to my desktop which uses NEVIDE display card,
it works well.
At 1).b) case, I find i915 binds one pipeline per display. It means even with
DP1.2 MST, i915 driver still restricts the display number to the display pipeline number. Am I right? Can we extend display number more than pipeline number?
I'm not sure if I followed your case here, but 2 things here:
- it seems that
you might be reached the maximun number of allocated vcpi here.
Just by leaving cable connected the vpci gets reserved on drm if I remember correctly so things might not fully work.
But it is hard to tell without any log. if that is the case.
- About the "extend display part" there is currently a limitation of the vertical
size that Ville was working to solve that. I'm not sure about the status.
Thanks, Rodrigo.
Thanks, Yanmin
-----Original Message----- From: Zhang, Yanmin Sent: Friday, November 30, 2018 8:24 AM To: Vivi, Rodrigo rodrigo.vivi@intel.com Cc: Syrjala, Ville ville.syrjala@intel.com Subject: RE: DP1.2 MST HUB
Rodrigo,
Thanks for the kind info. 'enabling' here is to check if DP1.2 MST (perhaps with HBR2) can work with intel NUC (with type-C DP). Later on, check it on new IVE system which might be based on ElkhartLake or Tigerlake. If it doesn't work, I have to check if it's about either MST HUB hardware, or software such like i915 driver. Basically, I am not i915 driver expert, but I assume you guys already enabled it well.
I already ordered a MST HUB https://www.club- 3d.com/en/detail/2411/multi_stream_transport_(mst)_hub_displayportt_ 1.2_qu ad_monitor/, and another one which has an input of USB Type-C and 2 HDMI outputs. Hope it can work.
Even when it works, IVE system might not use the MST HUB directly. I suppose IVE hardware architect will use specific AIC to implement MST HUB capability on board. Currently, I want to prove DP 1.2 MST can work
well on Intel chips.
I will keep you guys posted.
Yanmin
-----Original Message----- From: Vivi, Rodrigo Sent: Friday, November 30, 2018 1:45 AM To: Zhang, Yanmin yanmin.zhang@intel.com Cc: Syrjala, Ville ville.syrjala@intel.com Subject: Re: DP1.2 MST HUB
Hi Yanmin,
On Wed, Nov 28, 2018 at 05:03:02PM -0800, Zhang, Yanmin wrote:
Dear GFX/display experts,
maybe it would be probably good to ask to dri-devel and/or intel-gfx at lists.freedesktop.org
Would you like to share some info about MST HUB? I am enabling
multiple
display support by MST.
What do you mean by "enabling" here?
Currently, I have a KBL NUC which has a USB-Type C port. By aUSB Type-C to DP cable, it connect to a display panel and it can work well. KBL NUC prod spec says it can extend to connect multiple displays by DP1.2 MST. What MST HUB should be used?
short answer: Any dongle that supports DP1.2 MST.
However dongles can have firmware doing non compliant things that could cause headaches. So I'd recommend to get one that is know to have a
good quality.
Unfortunately I don't have any one specific to recommend.
If I buy a HUB like[1]https://item.taobao.com/item.htm?spm=a230r.1.14.110.32f348d5JPpMM s&
i
d=43812089455&ns=1&abbucket=17#detail , can I use that type-C to DP conversion cable to connect to the HUB and MST still works?
How about [2]http://item.jd.com/10210412498.html?
Can I use another simple HUB like[3]http://item.jd.com/28683591806.html?
Above links have Chinese characters, but the pictures and some English text are clear.
Well, first link doesn't work and I couldn't extract any useful information from the english parts. But if they implement DP MST properly it
should just work.
Would you like to give me your expert comments on that?
try it out and let me know if it works :P
Cheers, Rodrigo.
Thanks,
Yanmin
References
https://item.taobao.com/item.htm?spm=a230r.1.14.110.32f348d5JPpMMs&i d=
4 3812089455&ns=1&abbucket=17#detail