Hi All,

we are also seeing the CRC Errors in our setup (rpi4, Kernel 5.10.x)
from time to time. I just wanted to post here what I am seeing, maybe it helps...

[    6.761711] spi_master spi1: will run message pump with realtime priority
[    6.778063] mcp251xfd spi1.0 can1: MCP2518FD rev0.0 (-RX_INT -MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD c:40.00MHz m:20.00MHz r:17.00MHz e:16.66MHz) successfully initialized.

[ 4327.107856] mcp251xfd spi1.0 canfd1: CRC read error at address 0x0010 (length=4, data=00 cc 62 c4, CRC=0xa3a0) retrying.
[ 7770.163335] mcp251xfd spi1.0 canfd1: CRC read error at address 0x0010 (length=4, data=00 bf 16 d5, CRC=0x9d3c) retrying.
[ 8000.565955] mcp251xfd spi1.0 canfd1: CRC read error at address 0x0010 (length=4, data=00 40 66 fa, CRC=0x31d7) retrying.
[ 9753.658173] mcp251xfd spi1.0 canfd1: CRC read error at address 0x0010 (length=4, data=80 e9 01 4e, CRC=0xe862) retrying.


Sven

-----Ursprüngliche Nachricht-----
Von: Thomas.Kopp@microchip.com [off-list ref]
Gesendet: Donnerstag, 9. Dezember 2021 11:22
An: pavel.modilaynen@volvocars.com; mkl@pengutronix.de
Cc: drew@beagleboard.org; linux-can@vger.kernel.org; menschel.p@posteo.de;
netdev@vger.kernel.org; will@macchina.cc
Betreff: RE: [net-next 6/6] can: mcp251xfd: mcp251xfd_regmap_crc_read(): work around
broken CRC on TBC register

Hi Pavel,

quoted

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!)

What settings do you have on your setup? Can you please print the dmesg output from the
init? I'm especially interested in Sysclk and SPI speed.

Thanks,
Thomas