Hello Marc, We observe the very similar issue with MCP2517FD. >The CRC errors the patch works around are CRC errors introduced by a >chip erratum, not by electromagnetic interference. In my observation Are you referring this errata doc https://datasheet.octopart.com/MCP2517FD-H-JHA-Microchip-datasheet-136609045.pdf ? We have the similar CRC read errors but the lowest byte is not 0x00 and 0x80, it's actually 0x0x or 0x8x, e.g. mcp251xfd spi0.0 can0: CRC read error at address 0x0010 (length=4, data=82 d1 fa 6c, CRC=0xd9c2) retrying. 0xb0 0x10 0x04 0x82 0xd1 0xfa 0x6c => 0x59FD (not matching) but if I flip the first received bit (highest bit in the lowest byte): 0xb0 0x10 0x04 0x02 0xd1 0xfa 0x6c => 0xD9C2 (matching!) So, your fix covers only the case of 0x00 and 0x80, do you think that the workaround should be extended so check (buf_rx->data[0] == 0x0 || buf_rx->data[0] == 0x80)) { turns into ((buf_rx->data[0] & 0xf0) == 0x0 || (buf_rx->data[0] & 0xf0) == 0x80)) { Errata, actually says "Only bits 7/15/23/31 of the following registers can be affected:" So, we could basically, in simplest case flip bit 31 and re-check CRC without any check of rx->data[0].... Regards, Pavel
