xz: improve the MicroLZMA kernel-doc in xz.h

Move the description of the format into a "DOC:" comment.  Emphasize that
MicroLZMA functions aren't usually needed.

Link: https://lkml.kernel.org/r/20240721133633.47721-7-lasse.collin@tukaani.org
Signed-off-by: Lasse Collin <lasse.collin@tukaani.org>
Reviewed-by: Sam James <sam@gentoo.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jubin Zhong <zhongjubin@huawei.com>
Cc: Jules Maselbas <jmaselbas@zdiv.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Rui Li <me@lirui.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/xz.h b/include/linux/xz.h
index af1e075d9adda6868d9b6507d430526fb208e055..701d62c02b9a8da0715e0c33931b45f25850159c 100644 (file)
--- a/include/linux/xz.h
+++ b/include/linux/xz.h
@@ -232,9 +232,18 @@ XZ_EXTERN void xz_dec_reset(struct xz_dec *s);
  */
 XZ_EXTERN void xz_dec_end(struct xz_dec *s);
 
-/*
- * Decompressor for MicroLZMA, an LZMA variant with a very minimal header.
- * See xz_dec_microlzma_alloc() below for details.
+/**
+ * DOC: MicroLZMA decompressor
+ *
+ * This MicroLZMA header format was created for use in EROFS but may be used
+ * by others too. **In most cases one needs the XZ APIs above instead.**
+ *
+ * The compressed format supported by this decoder is a raw LZMA stream
+ * whose first byte (always 0x00) has been replaced with bitwise-negation
+ * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is
+ * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
+ * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
+ * marker must not be used. The unused values are reserved for future use.
  *
  * These functions aren't used or available in preboot code and thus aren't
  * marked with XZ_EXTERN. This avoids warnings about static functions that
@@ -262,15 +271,6 @@ struct xz_dec_microlzma;
  * On success, xz_dec_microlzma_alloc() returns a pointer to
  * struct xz_dec_microlzma. If memory allocation fails or
  * dict_size is invalid, NULL is returned.
- *
- * The compressed format supported by this decoder is a raw LZMA stream
- * whose first byte (always 0x00) has been replaced with bitwise-negation
- * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is
- * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
- * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
- * marker must not be used. The unused values are reserved for future use.
- * This MicroLZMA header format was created for use in EROFS but may be used
- * by others too.
  */
 extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
                                                       uint32_t dict_size);