linux-kernel - [PATCH 2/3] regmap: Make regmap_noinc_read() return -ENOTSUPP if map->read isn't set

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Date:   Thu, 16 Jun 2022 09:34:34 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Marek Vasut <marex@...x.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Brown <broonie@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: [PATCH 2/3] regmap: Make regmap_noinc_read() return -ENOTSUPP if map->read isn't set

Before adding support to define bulk read/write callbacks in regmap_config
by the commit d77e74561368 ("regmap: Add bulk read/write callbacks into
regmap_config"), the regmap_noinc_read() function returned an errno early
a map->bus->read callback wasn't set.

But that commit dropped the check and now a call to _regmap_raw_read() is
attempted even when bulk read operations are not supported. That function
checks for map->read anyways but there's no point to continue if the read
can't succeed.

Also is a fragile assumption to make so is better to make it fail earlier.

Fixes: d77e74561368 ("regmap: Add bulk read/write callbacks into regmap_config")
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

 drivers/base/regmap/regmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index e5bb70374ffc..f37f80a52115 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -2904,6 +2904,9 @@ int regmap_noinc_read(struct regmap *map, unsigned int reg,
 	size_t read_len;
 	int ret;

+	if (!map->read)
+		return -ENOTSUPP;
+
 	if (val_len % map->format.val_bytes)
 		return -EINVAL;
 	if (!IS_ALIGNED(reg, map->reg_stride))
-- 
2.36.1