kernel: mtdsplit: document Seama splitter a bit

[openwrt.git] / target / linux / generic / files / drivers / mtd / mtdsplit / mtdsplit_seama.c

diff --git a/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_seama.c b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_seama.c
index 6f21f8f..4ff361c 100644 (file)
--- a/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_seama.c
+++ b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_seama.c
@@ -33,7 +33,7 @@ static int mtdsplit_parse_seama(struct mtd_info *master,
                                struct mtd_part_parser_data *data)
 {
        struct seama_header hdr;
-       size_t hdr_len, retlen, kernel_size;
+       size_t hdr_len, retlen, kernel_ent_size;
        size_t rootfs_offset;
        struct mtd_partition *parts;
        int err;
@@ -50,18 +50,20 @@ static int mtdsplit_parse_seama(struct mtd_info *master,
        if (be32_to_cpu(hdr.magic) != SEAMA_MAGIC)
                return -EINVAL;
 
-       kernel_size = hdr_len + be32_to_cpu(hdr.size) +
-                     be16_to_cpu(hdr.metasize);
-       if (kernel_size > master->size)
+       kernel_ent_size = hdr_len + be32_to_cpu(hdr.size) +
+                         be16_to_cpu(hdr.metasize);
+       if (kernel_ent_size > master->size)
                return -EINVAL;
 
-       /* Find the rootfs after the kernel. */
-       err = mtd_check_rootfs_magic(master, kernel_size);
+       /* Check for the rootfs right after Seama entity with a kernel. */
+       err = mtd_check_rootfs_magic(master, kernel_ent_size);
        if (!err) {
-               rootfs_offset = kernel_size;
+               rootfs_offset = kernel_ent_size;
        } else {
                /*
-                * The size in the header might cover the rootfs as well.
+                * On some devices firmware entity might contain both: kernel
+                * and rootfs. We can't determine kernel size so we just have to
+                * look for rootfs magic.
                 * Start the search from an arbitrary offset.
                 */
                err = mtd_find_rootfs_from(master, SEAMA_MIN_ROOTFS_OFFS,