Re:Apple finally put USB-C in new iPhone, but limited to 23-...
by dataworm on Wednesday September 13, 2023 @11:29AM
(#37498095)
There is no separate USB3 host controller on the M1, it has a dual-role device USB 3.1 controller which supports up to 10 Gb/s and can act both in host and device modes.
The 40 Gb/s speed on the iPad Pro comes from the Thunderbolt controller, which is completely unrelated to USB and disabled in software on the 5th gen iPad Air for market segmentation.
The 4th gen iPad Air and 6th gen iPad Mini use a USB 2.0 dual-role device controller integrated into the SoC, which is limited to 480 Mb/s, and a USB 3.0 controller connected over PCIe, which supports up to 5 Gb/s.
The PCIe USB controller isn't included on the 10th gen iPad. It doesn't support device mode, which explains the USB 2.0 speeds when connected to a computer.
- the 4th gen ipad air supports 5Gb USB, the 10th gen iPad only supports 0.5Gb, both use an A14
- the 5th gen ipad pro supports 40Gb USB, the 5th gen ipad air only supports 10Gb, both use an M1
But I've been told these ports are not symmetrical, the highest speeds are only in host mode and come from a separate USB3 controller, and the soc integrated device mode has much lower specs (10G for the Pro, 0.5Gb on the A15-using 6th gen mini — 5Gb capable in host mode).