> again, it's all already on PCIe no matter which way you cut it..
This is why I said the "it's ironic" part. First, realize that under no circumstances a USB link would be "higher power" than a PCIe link just because logically there is a USB controller which connects via PCIe "no matter which way you cut it, precisely because in a way it matters "which way you cut [the interfaces]". An USB link can be as low as 2 wires. Make the math...
> apple have literally done this in their new macs, and the blog post specifies what they had to do to make it work in asahi: send the bluetooth HCI messages over the PCIe transport directly!
And how do we even know if this is the correct, low power behavior? Have they implemented runtime power management for this device? D3cold rings a bell ?
For better or worse, power management _is_ a well understood problem with USB devices & controllers; you can be pretty sure the Linux USB controller driver is as low-power as it gets; you have much fewer assurances if you go directly to the PCIe. I'm quite sure that the "mysterious connectivity issues" you attribute to USB are in part due to runtime power management logic.
This is why I said the "it's ironic" part. First, realize that under no circumstances a USB link would be "higher power" than a PCIe link just because logically there is a USB controller which connects via PCIe "no matter which way you cut it, precisely because in a way it matters "which way you cut [the interfaces]". An USB link can be as low as 2 wires. Make the math...
> apple have literally done this in their new macs, and the blog post specifies what they had to do to make it work in asahi: send the bluetooth HCI messages over the PCIe transport directly!
And how do we even know if this is the correct, low power behavior? Have they implemented runtime power management for this device? D3cold rings a bell ?
For better or worse, power management _is_ a well understood problem with USB devices & controllers; you can be pretty sure the Linux USB controller driver is as low-power as it gets; you have much fewer assurances if you go directly to the PCIe. I'm quite sure that the "mysterious connectivity issues" you attribute to USB are in part due to runtime power management logic.