diff options
Diffstat (limited to 'include/linux/mtd/ubi.h')
-rw-r--r-- | include/linux/mtd/ubi.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h index b31bd9e..84854ed 100644 --- a/include/linux/mtd/ubi.h +++ b/include/linux/mtd/ubi.h @@ -116,18 +116,40 @@ struct ubi_volume_info { * struct ubi_device_info - UBI device description data structure. * @ubi_num: ubi device number * @leb_size: logical eraseblock size on this UBI device + * @leb_start: starting offset of logical eraseblocks within physical + * eraseblocks * @min_io_size: minimal I/O unit size + * @max_write_size: maximum amount of bytes the underlying flash can write at a + * time (MTD write buffer size) * @ro_mode: if this device is in read-only mode * @cdev: UBI character device major and minor numbers * * Note, @leb_size is the logical eraseblock size offered by the UBI device. * Volumes of this UBI device may have smaller logical eraseblock size if their * alignment is not equivalent to %1. + * + * The @max_write_size field describes flash write maximum write unit. For + * example, NOR flash allows for changing individual bytes, so @min_io_size is + * %1. However, it does not mean than NOR flash has to write data byte-by-byte. + * Instead, CFI NOR flashes have a write-buffer of, e.g., 64 bytes, and when + * writing large chunks of data, they write 64-bytes at a time. Obviously, this + * improves write throughput. + * + * Also, the MTD device may have N interleaved (striped) flash chips + * underneath, in which case @min_io_size can be physical min. I/O size of + * single flash chip, while @max_write_size can be N * @min_io_size. + * + * The @max_write_size field is always greater or equivalent to @min_io_size. + * E.g., some NOR flashes may have (@min_io_size = 1, @max_write_size = 64). In + * contrast, NAND flashes usually have @min_io_size = @max_write_size = NAND + * page size. */ struct ubi_device_info { int ubi_num; int leb_size; + int leb_start; int min_io_size; + int max_write_size; int ro_mode; dev_t cdev; }; |