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This driver was originally written for the Intel MRST platform with several platform-specific parameters hard-coded. Currently, the ECC settings are hard-coded as follows: #define ECC_SECTOR_SIZE 512 #define ECC_8BITS 14 #define ECC_15BITS 26 Therefore, the driver can only support two cases. - ecc.size = 512, ecc.strength = 8 --> ecc.bytes = 14 - ecc.size = 512, ecc.strength = 15 --> ecc.bytes = 26 However, these are actually customizable parameters, for example, UniPhier platform supports the following: - ecc.size = 1024, ecc.strength = 8 --> ecc.bytes = 14 - ecc.size = 1024, ecc.strength = 16 --> ecc.bytes = 28 - ecc.size = 1024, ecc.strength = 24 --> ecc.bytes = 42 So, we need to handle the ECC parameters in a more generic manner. Fortunately, the Denali User's Guide explains how to calculate the ecc.bytes. The formula is: ecc.bytes = 2 * CEIL(13 * ecc.strength / 16) (for ecc.size = 512) ecc.bytes = 2 * CEIL(14 * ecc.strength / 16) (for ecc.size = 1024) For DT platforms, it would be reasonable to allow DT to specify ECC strength by either "nand-ecc-strength" or "nand-ecc-maximize". If none of them is specified, the driver will try to meet the chip's ECC requirement. For PCI platforms, the max ECC strength is used to keep the original behavior. Newer versions of this IP need ecc.size and ecc.steps explicitly set up via the following registers: CFG_DATA_BLOCK_SIZE (0x6b0) CFG_LAST_DATA_BLOCK_SIZE (0x6c0) CFG_NUM_DATA_BLOCKS (0x6d0) For older IP versions, write accesses to these registers are just ignored. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.