Device-tree improvements

This is for any ARMv7 device that we do not officially support.

Re: Device-tree improvements

Postby summers » Tue Nov 26, 2019 11:40 am

Whats behind all this, is evolution in the kernel. It was realized that many bits of hardware were connected to the CPU via a UART; and then the driver for that bit of hardware had to take control of the uart.

Now given that the kernel already has ways to handle the UART, flow control, and all that the serdev concept arose; have the serial driver handle the uart and so communications to the hardware; the driver then can focus on what to do with the data, and handle discrete lines that often lie along side the uart, e.g. chip enable.

Now hassle is that drivers need to be rewritten in this way, and some have, but many not. Also as far as I can see there isn't any ongoing activity to rewrite drivers.

Now the hci_h5 driver may work anyway, but it has issues, e.g. how does it know which uart the 3 wire interface is connected to. So hci_h5 isn't really the method to do this. Or at least it needs to be strongly tied to the device tree that can explain how cpu pins are wired to bluetooth chip.

hence why it makes sense to convert to serdev - its just a more reasonable way of describing the system.
summers
 
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