can: tcan4x5x: rework SPI access
This patch reworks the SPI access and fixes several probems:
- tcan4x5x_regmap_gather_write(), tcan4x5x_regmap_read():
Do not place variable "addr" on stack and use it as buffer for SPI
transfer. Buffers for SPI transfers must be allocated from DMA save
memory.
- tcan4x5x_regmap_gather_write(), tcan4x5x_regmap_read():
Halfe number of SPI transfers by using a single buffer + memcpy().
This improves the performance, especially on SPI controllers, which
use interrupt based transfers.
- Use "8" bits per word, not "32". This makes it possible to use this
driver on SoCs like the Raspberry Pi, which SPI host controller
drivers only support 8 bits per word.
Note: this breaks half duplex only controllers. Support for them will be
re-added in the next patch.
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Tested-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-16-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
3 files changed