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The Denali IP adopts the syndrome page layout; payload and ECC are interleaved, with BBM area always placed at the beginning of OOB. The figure below shows the page organization for ecc->steps == 2: |----------------| |-----------| | | | | | | | | | Payload0 | | | | | | | | | | | | | | | |----------------| | in-band | | ECC0 | | area | |----------------| | | | | | | | | | | | Payload1 | | | | | | | | | | | |----------------| |-----------| | BBM | | | |----------------| | | |Payload1 (cont.)| | | |----------------| |out-of-band| | ECC1 | | area | |----------------| | | | OOB free | | | |----------------| |-----------| The current raw / oob accessors do not take that into consideration, so in-band and out-of-band data are transferred as stored in the device. In the case above, in-band: Payload0 + ECC0 + Payload1(partial) out-of-band: BBM + Payload1(cont.) + ECC1 + OOB-free This is wrong. As the comment block of struct nand_ecc_ctrl says, driver callbacks must hide the specific layout used by the hardware and always return contiguous in-band and out-of-band data. The current implementation is completely screwed-up, so read/write callbacks must be re-worked. Also, it is reasonable to support PIO transfer in case DMA may not work for some reasons. Actually, the Data DMA may not be equipped depending on the configuration of the RTL. This can be checked by reading the bit 4 of the FEATURES register. Even if the controller has the DMA support, dma_set_mask() and dma_map_single() could fail. In either case, the driver can fall back to the PIO transfer. Slower access would be better than giving up. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> 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.