On Thu, Jan 09, 2020 at 03:54:00PM +0000, John Garry wrote:

> From checking acpi_spi_add_resource() or anywhere else, I cannot see how
> SPI_RX_DUAL or the others are set for spi_device.mode. What am I missing?
> Are these just not supported yet for ACPI? Or should the spi-nor code not be
> relying on this since we should be able to get this info from the SPI NOR
> part?

I'm not aware of any work on integrating this sort of stuff into ACPI
platforms so I think it's just not yet supported in ACPI.  I'm not
really sure what would be idiomatic for ACPI, figuring it out from what
the part supports might well be idiomatic there though I don't know how
common it is for people not to wire up all the data lines even if both
controller and device support wider transfers.  I've got a horrible
feeling that the idiomatic thing is a combination of that and a bunch of
per-device quirks.  There may be a spec I'm not aware of though I'd be a
bit surprised.