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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: volvocars.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PR3P174MB0112.EURP174.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-Network-Message-Id: 71dc2736-bdf4-4ef9-c773-08d9b9a20e31 X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Dec 2021 16:53:12.2484 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 81fa766e-a349-4867-8bf4-ab35e250a08f X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: Fw8SWcPTtypmA9HgRJxjgUJl/eoT71T1Md9aOnFqPQhILAFQSurGjKtqC9wllQE1H6obfhi2PFC2/QkB4xQh4w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3P174MB0109 Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org Hello Marc,=0A= =0A= We observe the very similar issue with MCP2517FD.=0A= =0A= >The CRC errors the patch works around are CRC errors introduced by a=0A= >chip erratum, not by electromagnetic interference. In my observation=0A= =0A= Are you referring this errata doc=0A= https://datasheet.octopart.com/MCP2517FD-H-JHA-Microchip-datasheet-13660904= 5.pdf ?=0A= =0A= We have the similar CRC read errors but=0A= the lowest byte is not 0x00 and 0x80, it's actually 0x0x or 0x8x, e.g.=0A= =0A= mcp251xfd spi0.0 can0: CRC read error at address 0x0010 (length=3D4, data= =3D82 d1 fa 6c, CRC=3D0xd9c2) retrying.=0A= =0A= 0xb0 0x10 0x04 0x82 0xd1 0xfa 0x6c =3D> 0x59FD (not matching)=0A= =0A= but if I flip the first received bit (highest bit in the lowest byte):=0A= 0xb0 0x10 0x04 0x02 0xd1 0xfa 0x6c =3D> 0xD9C2 (matching!)=0A= =0A= So, your fix covers only the case of 0x00 and 0x80, =0A= do you think that the workaround should be extended so check=0A= (buf_rx->data[0] =3D=3D 0x0 || buf_rx->data[0] =3D=3D 0x80)) {=0A= turns into =0A= ((buf_rx->data[0] & 0xf0) =3D=3D 0x0 || (buf_rx->data[0] & 0xf0) =3D= =3D 0x80)) {=0A= =0A= Errata, actually says=0A= "Only bits 7/15/23/31 of the following registers can be affected:"=0A= =0A= So, we could basically, in simplest case flip bit 31 and re-check CRC witho= ut any check of =0A= rx->data[0]....=0A= =0A= Regards,=0A= Pavel=0A= =0A= =0A=