Does anyone know the answer to this? I've answered a couple of questions about why there is no HDMI 2.1, which I assume is a bandwidth limitation, but I started to wonder whether the available bandwidth for the ports is only 80Gbps total (2 TB controllers @ 40Gbps bi-directional), or whether there are 3 or 4 controllers?
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Do the new MBPs still have only 2 Thunderbolt Controllers?
- Thread starter Fomalhaut
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The HDMI port does not have anything todo with the TB controller though, more likely the display engine is out of bandwidth to support a higher resolution. It need to drive 3 XDR level external screens, plus the internal screen, plus an HDMI 2.0 screen after all. If there is no internal screen, it could probably drive 4 XDR level screen (speculation) and we can have an HDMI 2.1 port.
That is still ambiguous and could just be positive marketing spin - yes, each port is capable of 40Gbps individually, as they are on the M1, but what if you run a 3 ports at maximum bandwidth simultanously, plus HDMI plus SD card?
Is the bandwidth shared (as it is on the Intel MBPs) or one controller per port?
On Intel based macs, we have one less TB controllers and there are only 2 TB controllers on the 4 port models. The port on each side shares the bandwidth. It is easy to notice that we are losing one TB port, but in fact we are having 40GB/s more bandwidth in total because we don't share controllers between TB ports on AS Macs.
No. There is a controller for each Thunderbolt port on the MacBook Pro. They are twice as capable as before, because they are not sharing controllers.
I thought the SD Card and the HDMI port shared a controller with one of the three?
SD reader is directly connected to PCIe (1 lane it looks like), HDMI seems to be directly connected to a DisplayPort output from the display controller(s). There's not much benefit to hooking these up to Thunderbolt if you can avoid it, as it just complicates things.
Documented by Apple? My MacBook Pro system profile shows 3 Thunderbolt controllers. There are 3 Thunderbolt ports. The SD and HDMI ports are handled differently.
Yes this seems to be a realistic issue, say you are on a video centric setup and you want to maximize bandwidth available through the 3 TB4 ports, in which case if you have one external display it is best leaving it to the HDMI which is not going to take anything away from the TB4 buses. However the HDMI is "only" 2.0 whereas DP alt mode over the TB ports will unlock the bandwidth / supported specs further, which you may very well need for proofing purposes.
But anyway for a portable this is already a really flexible and high bandwidth I/O profile.