{"id":2196997,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2196997/?format=json","project":{"id":18,"url":"http://patchwork.ozlabs.org/api/1.0/projects/18/?format=json","name":"U-Boot","link_name":"uboot","list_id":"u-boot.lists.denx.de","list_email":"u-boot@lists.denx.de","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<861a2d0ad1519879d8e2bfcd67ebec605e31f7a1.1771275704.git.daniel@makrotopia.org>","date":"2026-02-16T21:21:40","name":"[RFC,03/20] mtd: add mtd_read_skip_bad() helper","commit_ref":null,"pull_url":null,"state":"rfc","archived":false,"hash":"7f90bf2d25a227b4aa8539813c03eb7d77374946","submitter":{"id":64091,"url":"http://patchwork.ozlabs.org/api/1.0/people/64091/?format=json","name":"Daniel Golle","email":"daniel@makrotopia.org"},"delegate":{"id":3651,"url":"http://patchwork.ozlabs.org/api/1.0/users/3651/?format=json","username":"trini","first_name":"Tom","last_name":"Rini","email":"trini@ti.com"},"mbox":"http://patchwork.ozlabs.org/project/uboot/patch/861a2d0ad1519879d8e2bfcd67ebec605e31f7a1.1771275704.git.daniel@makrotopia.org/mbox/","series":[{"id":492351,"url":"http://patchwork.ozlabs.org/api/1.0/series/492351/?format=json","date":"2026-02-16T21:21:14","name":"boot: add OpenWrt boot method and on-demand FIT loading","version":1,"mbox":"http://patchwork.ozlabs.org/series/492351/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2196997/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.denx.de\n (client-ip=2a01:238:438b:c500:173d:9f52:ddab:ee01; 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Mon, 16 Feb 2026 22:22:00 +0100 (CET)","from local\n by pidgin.makrotopia.org with esmtpsa (TLS1.3:TLS_AES_256_GCM_SHA384:256)\n (Exim 4.99) (envelope-from )\n id 1vs62K-000000002d2-1XXb; Mon, 16 Feb 2026 21:21:44 +0000"],"X-Spam-Checker-Version":"SpamAssassin 3.4.2 (2018-09-13) on phobos.denx.de","X-Spam-Level":"","X-Spam-Status":"No, score=-1.9 required=5.0 tests=BAYES_00,\n RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham\n autolearn_force=no version=3.4.2","Date":"Mon, 16 Feb 2026 21:21:40 +0000","From":"Daniel Golle ","To":"Tom Rini , Simon Glass ,\n Quentin Schulz ,\n Daniel Golle ,\n Kory Maincent ,\n Mattijs Korpershoek ,\n Martin Schwan , Anshul Dalal ,\n Ilias Apalodimas ,\n Sughosh Ganu , Aristo Chen ,\n\t=?utf-8?b?54mbIOW/l+Wujw==?= ,\n Marek Vasut ,\n Heinrich Schuchardt ,\n Wolfgang Wallner ,\n Frank Wunderlich ,\n David Lechner ,\n Osama Abdelkader ,\n Mikhail Kshevetskiy ,\n Michael Trimarchi ,\n Miquel Raynal ,\n Andrew Goodbody ,\n Yegor Yefremov ,\n Mike Looijmans ,\n Weijie Gao ,\n Alexander Stein ,\n Neil Armstrong ,\n Mayuresh Chitale ,\n Paul HENRYS , u-boot@lists.denx.de","Cc":"John Crispin , Paul Spooren ","Subject":"[RFC PATCH 03/20] mtd: add mtd_read_skip_bad() helper","Message-ID":"\n <861a2d0ad1519879d8e2bfcd67ebec605e31f7a1.1771275704.git.daniel@makrotopia.org>","References":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","Content-Transfer-Encoding":"8bit","In-Reply-To":"","X-Mailman-Approved-At":"Mon, 16 Feb 2026 22:22:55 +0100","X-BeenThere":"u-boot@lists.denx.de","X-Mailman-Version":"2.1.39","Precedence":"list","List-Id":"U-Boot discussion ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"u-boot-bounces@lists.denx.de","Sender":"\"U-Boot\" ","X-Virus-Scanned":"clamav-milter 0.103.8 at phobos.denx.de","X-Virus-Status":"Clean"},"content":"Add a generic mtd_read_skip_bad() helper to the MTD core that reads\ndata from an MTD device while transparently skipping bad erase blocks\non NAND.\n\nThe function takes a physical byte offset, reads in erase-block-sized\nchunks, and automatically skips any block where mtd_block_isbad()\nreturns true. Non-block-aligned start offsets are handled correctly.\nFor NOR and other device types without bad-block support, it falls\nthrough to a plain mtd_read().\n\nRefactor the plain-data read path in cmd/mtd.c (\"mtd read\", without\n.raw or .oob suffixes) to use the new helper instead of open-coding\nthe bad-block skip loop. The write path and OOB/raw read paths\nretain their existing page-at-a-time mtd_read_oob() loop.\n\nThis helper will also be used by the image_loader MTD backend in a\nsubsequent patch. It could also serve as a replacement for\nnand_read_skip_bad() in drivers/mtd/nand/raw/nand_util.c in the\nfuture.\n\nSigned-off-by: Daniel Golle \n---\n cmd/mtd.c | 65 +++++++++++++++++++++++------------------\n drivers/mtd/mtdcore.c | 45 ++++++++++++++++++++++++++++\n include/linux/mtd/mtd.h | 24 +++++++++++++++\n 3 files changed, 106 insertions(+), 28 deletions(-)","diff":"diff --git a/cmd/mtd.c b/cmd/mtd.c\nindex 7f25144098b..30e4845b26d 100644\n--- a/cmd/mtd.c\n+++ b/cmd/mtd.c\n@@ -551,12 +551,6 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc,\n \t\tprintf(\"%s %lld byte(s) at offset 0x%08llx\\n\",\n \t\t read ? \"Reading\" : \"Writing\", len, start_off);\n \n-\tio_op.mode = raw ? MTD_OPS_RAW : MTD_OPS_AUTO_OOB;\n-\tio_op.len = has_pages ? mtd->writesize : len;\n-\tio_op.ooblen = woob ? mtd->oobsize : 0;\n-\tio_op.datbuf = buf;\n-\tio_op.oobbuf = woob ? &buf[len] : NULL;\n-\n \t/* Search for the first good block after the given offset */\n \toff = start_off;\n \twhile (mtd_block_isbad(mtd, off))\n@@ -567,31 +561,46 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc,\n \tif (benchmark)\n \t\tbench_start = timer_get_us();\n \n-\t/* Loop over the pages to do the actual read/write */\n-\twhile (remaining) {\n-\t\t/* Skip the block if it is bad */\n-\t\tif (mtd_is_aligned_with_block_size(mtd, off) &&\n-\t\t mtd_block_isbad(mtd, off)) {\n-\t\t\toff += mtd->erasesize;\n-\t\t\tcontinue;\n-\t\t}\n+\tif (read && !raw && !woob) {\n+\t\t/* Plain data read — use the skip-bad-block helper */\n+\t\tsize_t rdlen;\n \n-\t\tif (read)\n-\t\t\tret = mtd_read_oob(mtd, off, &io_op);\n-\t\telse\n-\t\t\tret = mtd_special_write_oob(mtd, off, &io_op,\n-\t\t\t\t\t\t write_empty_pages, woob);\n+\t\tret = mtd_read_skip_bad(mtd, off, remaining, &rdlen, buf);\n+\t\tremaining -= rdlen;\n+\t} else {\n+\t\tio_op.mode = raw ? MTD_OPS_RAW : MTD_OPS_AUTO_OOB;\n+\t\tio_op.len = has_pages ? mtd->writesize : len;\n+\t\tio_op.ooblen = woob ? mtd->oobsize : 0;\n+\t\tio_op.datbuf = buf;\n+\t\tio_op.oobbuf = woob ? &buf[len] : NULL;\n+\n+\t\t/* Loop over the pages to do the actual read/write */\n+\t\twhile (remaining) {\n+\t\t\t/* Skip the block if it is bad */\n+\t\t\tif (mtd_is_aligned_with_block_size(mtd, off) &&\n+\t\t\t mtd_block_isbad(mtd, off)) {\n+\t\t\t\toff += mtd->erasesize;\n+\t\t\t\tcontinue;\n+\t\t\t}\n \n-\t\tif (ret) {\n-\t\t\tprintf(\"Failure while %s at offset 0x%llx\\n\",\n-\t\t\t read ? \"reading\" : \"writing\", off);\n-\t\t\tbreak;\n-\t\t}\n+\t\t\tif (read)\n+\t\t\t\tret = mtd_read_oob(mtd, off, &io_op);\n+\t\t\telse\n+\t\t\t\tret = mtd_special_write_oob(mtd, off, &io_op,\n+\t\t\t\t\t\t\t write_empty_pages,\n+\t\t\t\t\t\t\t woob);\n+\n+\t\t\tif (ret) {\n+\t\t\t\tprintf(\"Failure while %s at offset 0x%llx\\n\",\n+\t\t\t\t read ? \"reading\" : \"writing\", off);\n+\t\t\t\tbreak;\n+\t\t\t}\n \n-\t\toff += io_op.retlen;\n-\t\tremaining -= io_op.retlen;\n-\t\tio_op.datbuf += io_op.retlen;\n-\t\tio_op.oobbuf += io_op.oobretlen;\n+\t\t\toff += io_op.retlen;\n+\t\t\tremaining -= io_op.retlen;\n+\t\t\tio_op.datbuf += io_op.retlen;\n+\t\t\tio_op.oobbuf += io_op.oobretlen;\n+\t\t}\n \t}\n \n \tif (benchmark && bench_start) {\ndiff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c\nindex 3bfa5aebbc6..eb36743af1f 100644\n--- a/drivers/mtd/mtdcore.c\n+++ b/drivers/mtd/mtdcore.c\n@@ -1684,6 +1684,51 @@ int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)\n }\n EXPORT_SYMBOL_GPL(mtd_block_markbad);\n \n+int mtd_read_skip_bad(struct mtd_info *mtd, loff_t from, size_t len,\n+\t\t size_t *retlen, u_char *buf)\n+{\n+\tsize_t remaining = len;\n+\tu_char *p = buf;\n+\tint ret;\n+\n+\t*retlen = 0;\n+\n+\tif (!mtd_can_have_bb(mtd)) {\n+\t\tret = mtd_read(mtd, from, len, retlen, buf);\n+\t\tif (ret == -EUCLEAN)\n+\t\t\tret = 0;\n+\t\treturn ret;\n+\t}\n+\n+\twhile (remaining) {\n+\t\tloff_t block_start = from & ~(loff_t)(mtd->erasesize - 1);\n+\t\tsize_t block_off = from - block_start;\n+\t\tsize_t chunk, rdlen;\n+\n+\t\tif (from >= mtd->size)\n+\t\t\treturn -EINVAL;\n+\n+\t\tif (mtd_block_isbad(mtd, block_start)) {\n+\t\t\t/* Skip to start of next erase block */\n+\t\t\tfrom = block_start + mtd->erasesize;\n+\t\t\tcontinue;\n+\t\t}\n+\n+\t\tchunk = min(remaining, (size_t)mtd->erasesize - block_off);\n+\n+\t\tret = mtd_read(mtd, from, chunk, &rdlen, p);\n+\t\tif (ret && ret != -EUCLEAN)\n+\t\t\treturn ret;\n+\n+\t\tp += rdlen;\n+\t\tfrom += rdlen;\n+\t\tremaining -= rdlen;\n+\t\t*retlen += rdlen;\n+\t}\n+\n+\treturn 0;\n+}\n+\n #ifndef __UBOOT__\n /*\n * default_mtd_writev - the default writev method\ndiff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h\nindex 1f97bc4fe11..ea3fa513c58 100644\n--- a/include/linux/mtd/mtd.h\n+++ b/include/linux/mtd/mtd.h\n@@ -471,6 +471,30 @@ int mtd_block_isreserved(struct mtd_info *mtd, loff_t ofs);\n int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs);\n int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs);\n \n+/**\n+ * mtd_read_skip_bad() - Read from an MTD device, skipping bad blocks\n+ *\n+ * Read @len bytes starting at physical offset @from into @buf. On NAND\n+ * devices, erase blocks that are marked bad are transparently skipped\n+ * so the caller always receives a contiguous stream of good data.\n+ *\n+ * If @from is not erase-block-aligned, reading starts at the correct\n+ * position within the first good block.\n+ *\n+ * For NOR and other device types without bad-block support, this is\n+ * equivalent to a plain mtd_read().\n+ *\n+ * @mtd:\tMTD device\n+ * @from:\tStart offset (physical, byte address)\n+ * @len:\tNumber of bytes to read\n+ * @retlen:\tActual number of bytes read (output)\n+ * @buf:\tDestination buffer\n+ * Return: 0 on success, negative errno on failure. -EUCLEAN is\n+ *\t treated as success (ECC corrected).\n+ */\n+int mtd_read_skip_bad(struct mtd_info *mtd, loff_t from, size_t len,\n+\t\t size_t *retlen, u_char *buf);\n+\n #ifndef __UBOOT__\n static inline int mtd_suspend(struct mtd_info *mtd)\n {\n","prefixes":["RFC","03/20"]}