linux-kernel - [RFC] regmap: clairify max

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Date:	Sun, 17 Jan 2016 22:52:56 -0800
From:	Stefan Agner <stefan@...er.ch>
To:	broonie@...nel.org
Cc:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	Stefan Agner <stefan@...er.ch>
Subject: [RFC] regmap: clairify max_register meaning

The exact meaning of max_register is not entirely clear. Define
it to be the maximum address offset a register in a regmap can
actually have. This seems to be the interpretation most commonly
used.

Fix regcache-flat to follow this definition.

Signed-off-by: Stefan Agner <stefan@...er.ch>
---
Hi Mark,

I stumbled upon this while switching to regmap cache FLAT for the
FSL DCU and PWM FTM drivers.

Maybe I see something completely wrong here, but to me it seems
that the regcache-flat.c is the only code interpreting max_register
as register indexes rather then the maximum relative address...
At least regmap.c compares with range_max, which seems to use
addresses.

If this is right, we should probably check the max_register values
of the drivers using REGCACHE_FLAT before fixing this... Some
drivers I checked seem to pass the maximum register address already.

--
Stefan

 drivers/base/regmap/regcache-flat.c | 3 +--
 include/linux/regmap.h              | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/base/regmap/regcache-flat.c b/drivers/base/regmap/regcache-flat.c
index 686c9e0..fe997c1 100644
--- a/drivers/base/regmap/regcache-flat.c
+++ b/drivers/base/regmap/regcache-flat.c
@@ -21,8 +21,7 @@ static int regcache_flat_init(struct regmap *map)
 	int i;
 	unsigned int *cache;

-	map->cache = kcalloc(map->max_register + 1, sizeof(unsigned int),
-			     GFP_KERNEL);
+	map->cache = kzalloc(map->max_register + map->reg_stride, GFP_KERNEL);
 	if (!map->cache)
 		return -ENOMEM;

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 1839434..27aaac9 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -162,7 +162,7 @@ typedef void (*regmap_unlock)(void *);
  *		  This field is a duplicate of a similar file in
  *		  'struct regmap_bus' and serves exact same purpose.
  *		   Use it only for "no-bus" cases.
- * @max_register: Optional, specifies the maximum valid register index.
+ * @max_register: Optional, specifies the maximum valid register address.
  * @wr_table:     Optional, points to a struct regmap_access_table specifying
  *                valid ranges for write access.
  * @rd_table:     As above, for read access.
-- 
2.7.0