linux-kernel - [PATCH] regmap: Drop early readability check

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Message-Id: <20230615-regmap-drop-early-readability-v1-1-8135094362de@kernel.org>
Date:   Fri, 16 Jun 2023 00:04:40 +0100
From:   Mark Brown <broonie@...nel.org>
To:     linux-kernel@...r.kernel.org,
        Konrad Dybcio <konradybcio@...nel.org>
Cc:     Mark Brown <broonie@...nel.org>
Subject: [PATCH] regmap: Drop early readability check

We have some drivers that have a use case for cached write only
registers, doing read/modify/writes on read only registers in order to
work more easily with bitfields.  Go back to trying the cache before we
check if we can read from the device.

Fixes: eab5abdeb79f0 ("regmap: Check for register readability before checking cache during read")
Reported-by: Konrad Dybcio <konradybcio@...nel.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/base/regmap/regmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index fad66b309ef9..89a7f1c459c1 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -2897,9 +2897,6 @@ static int _regmap_read(struct regmap *map, unsigned int reg,
 	int ret;
 	void *context = _regmap_map_get_context(map);
 
-	if (!regmap_readable(map, reg))
-		return -EIO;
-
 	if (!map->cache_bypass) {
 		ret = regcache_read(map, reg, val);
 		if (ret == 0)
@@ -2909,6 +2906,9 @@ static int _regmap_read(struct regmap *map, unsigned int reg,
 	if (map->cache_only)
 		return -EBUSY;
 
+	if (!regmap_readable(map, reg))
+		return -EIO;
+
 	ret = map->reg_read(context, reg, val);
 	if (ret == 0) {
 		if (regmap_should_log(map))

---
base-commit: 505cb70cd27abde24bd48b2c9a539cca485d722f
change-id: 20230615-regmap-drop-early-readability-3832b755ae14

Best regards,
-- 
Mark Brown <broonie@...nel.org>