Re: MCP251x SPI CAN controller on Cavium ThunderX

From: Mark Brown
Date: Thu Nov 16 2017 - 07:42:09 EST


On Wed, Nov 15, 2017 at 03:18:59PM -0800, Tim Harvey wrote:

> I could re-write the mcp251x driver to not use full-duplex but I'm
> assuming most SPI drivers use full-duplex transactions.

I'd not actually say that's the case - the bulk of devices do some kind
of command/response or register/value thing, full duplex is moderately
complex to work with and ends up needing a constant data stream between
the two devices. It does happen (and some controllers always transfer
data in both directions) but most of the time only one direction has any
meaning.

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