[PATCH v3 0/2] spi: support devices with no wire in one direction

[Cole Munz <Munzzyy1@proton.me>]

The Flipper One display bus has no MISO wire; the pin is the
end-of-frame GPIO. Patch 1 maps spi-{tx,rx}-bus-width = <0> to
SPI_NO_TX/SPI_NO_RX and validates transfers against the bits in
dm_spi_xfer(). Patch 2 has the Rockchip driver pick its transfer mode
from them so the unused FIFO stays out of the transfer. Background and
history are in the v2 cover letter:

https://lore.kernel.org/all/cover.1787238071.git.Munzzyy1@proton.me/

Changes in v3:
- dropped the happy path assertion from the new sandbox test, it is
  already covered by dm_test_spi_xfer (Quentin)
- collected Quentin's Acked-by on patch 1
- reworded the toread comment in rk_spi.c to say what the RX drain was
  actually doing for the transmit path (Quentin)

Cole Munz (2):
  spi: Handle spi-{tx,rx}-bus-width 0 as SPI_NO_TX/SPI_NO_RX
  spi: rockchip: skip the unused FIFO direction on a one-wire device

 drivers/spi/rk_spi.c     | 29 +++++++++++++++++++++++++----
 drivers/spi/spi-uclass.c | 16 ++++++++++++++++
 include/spi.h            |  2 ++
 test/dm/spi.c            | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 82 insertions(+), 4 deletions(-)


base-commit: 527115ef6783cec49e5610c523c124b399011361
-- 
2.55.0