mtd: mtdpart: Do not fail mtd probe when parsing partitions fails

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=5a2415b0769233194f20d3906c3ffc6a2033317c
Commit:     5a2415b0769233194f20d3906c3ffc6a2033317c
Parent:     04850c4d8613127a9b488321c0ad83bff7519311
Author:     Brian Norris <computersforpeace at gmail.com>
AuthorDate: Sun Oct 11 13:03:47 2015 -0700
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Oct 26 18:43:48 2015 -0700

    mtd: mtdpart: Do not fail mtd probe when parsing partitions fails
    
    Due to wrong assumption in ofpart ofpart fails on Exynos on SPI chips
    with no partitions because the subnode containing controller data
    confuses the ofpart parser.
    
    Thus compiling in ofpart support automatically fails probing any SPI NOR
    flash without partitions on Exynos.
    
    Compiling in a partitioning scheme should not cause probe of otherwise
    valid device to fail.
    
    Instead, let's do the following:
     * try parsers until one succeeds
     * if no parser succeeds, report the first error we saw
     * even in the failure case, allow MTD to probe, with fallback
       partitions or no partitions at all -- the master device will still be
       registered
    
    Issue report and comments initially by Michal Suchanek.
    
    Reported-by: Michal Suchanek <hramrach at gmail.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/mtdcore.c |  6 ++++--
 drivers/mtd/mtdpart.c | 14 ++++++++++----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 41dc501..b1eea48 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -598,8 +598,10 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 	}
 	/* Didn't come up with either parsed OR fallback partitions */
 	if (ret < 0) {
-		pr_info("mtd: failed to find partitions\n");
-		goto out;
+		pr_info("mtd: failed to find partitions; one or more parsers reports errors (%d)\n",
+			ret);
+		/* Don't abort on errors; we can still use unpartitioned MTD */
+		ret = 0;
 	}
 
 	ret = mtd_add_device_partitions(mtd, real_parts, ret);
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index f5279ea..f8ba153 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -755,12 +755,12 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
 			 struct mtd_part_parser_data *data)
 {
 	struct mtd_part_parser *parser;
-	int ret = 0;
+	int ret, err = 0;
 
 	if (!types)
 		types = default_mtd_part_types;
 
-	for ( ; ret <= 0 && *types; types++) {
+	for ( ; *types; types++) {
 		pr_debug("%s: parsing partitions %s\n", master->name, *types);
 		parser = get_partition_parser(*types);
 		if (!parser && !request_module("%s", *types))
@@ -776,10 +776,16 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
 		if (ret > 0) {
 			printk(KERN_NOTICE "%d %s partitions found on MTD device %s\n",
 			       ret, parser->name, master->name);
-			break;
+			return ret;
 		}
+		/*
+		 * Stash the first error we see; only report it if no parser
+		 * succeeds
+		 */
+		if (ret < 0 && !err)
+			err = ret;
 	}
-	return ret;
+	return err;
 }
 
 int mtd_is_partition(const struct mtd_info *mtd)