3 ms·
You could just use an USB device for higher throughput. The Sandisk Extreme Go, for example, is basically a small SSD in a USB drive form-factor.
by Legogris 7y ago
You could just use an USB device for higher throughput. The Sandisk Extreme Go, for example, is basically a small SSD in a USB drive form-factor.
- girvo 7y agoIf I’m reading it right, don’t you give up USB to get this PCIe access?
- megous 7y agoYes, that's my point.
- londons_explore 7y agoBet the broadcom SoC has a USB controller built in, but unused... You could hook it up?
- megous 7y agohttps://lb.raspberrypi.org/documentation/hardware/raspberrypi/usb/README.md https://lb.raspberrypi.org/documentation/hardware/raspberryp... This says, there's OTG controller intended to be used in "peripheral device only" mode. I haven't found datasheet for BCM2711, so it's hard to tell.
- londons_explore 7y ago> peripheral device only mode. I wonder why? The silicon required is far far simpler for host mode (since you only need a single memory buffer, and you fully dictate the timing, so can pass all the complex stuff up to software).
- megous 7y agoMaybe they don't have the VBUS circuitry setup for connecting self-powered devices in host mode.
- monocasa 7y agoThere's an XHCI controller in the device tree, but my guess is that there's some silicon bug in it, hence the third party chip off of PCIe instead.
- megous 7y agoAlso it's probably not routed from the BGA, so it would not be possible to use anyway.
- cesarb 7y agoIs it really unused? The RPi4 schematic is incomplete, but it at least shows the USB 2.0 pins of the USB-C port going somewhere; they might be going directly to that built-in USB controller in the main SoC.