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f7c9b38cc5
commite3d4ee7d5fupstream. The mcp251xfd compatible chips have an erratum ([1], [2]), where the received CRC doesn't match the calculated CRC. In commitc7eb923c3c("can: mcp251xfd: mcp251xfd_regmap_crc_read(): work around broken CRC on TBC register") the following workaround was implementierend. - If a CRC read error on the TBC register is detected and the first byte is 0x00 or 0x80, the most significant bit of the first byte is flipped and the CRC is calculated again. - If the CRC now matches, the _original_ data is passed to the reader. For now we assume transferred data was OK. New investigations and simulations indicate that the CRC send by the device is calculated on correct data, and the data is incorrectly received by the SPI host controller. Use flipped instead of original data and update workaround description in mcp251xfd_regmap_crc_read(). [1] mcp2517fd: DS80000792C: "Incorrect CRC for certain READ_CRC commands" [2] mcp2518fd: DS80000789C: "Incorrect CRC for certain READ_CRC commands" Link: https://lore.kernel.org/all/DM4PR11MB53901D49578FE265B239E55AFB7C9@DM4PR11MB5390.namprd11.prod.outlook.com Fixes:c7eb923c3c("can: mcp251xfd: mcp251xfd_regmap_crc_read(): work around broken CRC on TBC register") Cc: stable@vger.kernel.org Signed-off-by: Thomas Kopp <thomas.kopp@microchip.com> [mkl: split into 2 patches, update patch description and documentation] Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.