[v1,RFC,0/2] introduce fallback to pio in spi core

Message

Robin Gong June 11, 2020, 12:58 p.m. UTC

Introudce fallback pio way at spi core level so that the tx/rx buffer
mapped by spi core for dma could be unmap and fallback pio again. Hence no
need the below patch where 'dma_sync_sg_for_devic' to sync fresh data back
into 'device' memory and sync to 'cpu' again in spi core.
https://www.spinics.net/lists/arm-kernel/msg812236.html

If you want to use this fallback feature, please set 'master->flags' with
SPI_MASTER_FALLBACK and add 'master->fallback' checking in your can_dma()
to ensure it can fallback to pio.

Robin Gong (2):
  spi: introduce fallback to pio
  spi: spi-imx: add fallback feature

 drivers/spi/spi-imx.c   | 23 +++++------------------
 drivers/spi/spi.c       | 11 +++++++++++
 include/linux/spi/spi.h |  4 ++++
 3 files changed, 20 insertions(+), 18 deletions(-)