MCP251XFD_REG_OSC is the first register the driver reads from. The chip may be in deep sleep and the SPI transfer (i.e. the assertion of the CS) will wake the chip up. This takes about 3ms. The CRC of this transfer is wrong, or there isn't any chip at all, in this case the CRC will be wrong, too. The driver ignores the CRC error and returns the read data to the caller. To avoid any confusion, this patch changes the mcp251xfd_regmap_crc_read() function to only ignore the CRC error if solely the OSC register is read. So when reading more than the OSC registers at once, CRC errors are not ignored. Link: https://lore.kernel.org/all/20220207131047.282110-3-mkl@xxxxxxxxxxxxxx Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c index 7b120c716228..8112f8df22a6 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c @@ -368,7 +368,7 @@ mcp251xfd_regmap_crc_read(void *context, * to the caller. It will take care of both cases. * */ - if (reg == MCP251XFD_REG_OSC) { + if (reg == MCP251XFD_REG_OSC && val_len == sizeof(__le32)) { err = 0; goto out; } -- 2.34.1
