From e062bdfdd6adbb2dee7751d054c1d8df63ddb8b8 Mon Sep 17 00:00:00 2001 From: Sander Vanheule Date: Wed, 29 Oct 2025 09:12:48 +0100 Subject: [PATCH] regmap: warn users about uninitialized flat cache The standard flat cache did not contain any validity info, so the cache was always considered to be entirely valid. Multiple mechanisms exist to initialize the cache on regmap init (defaults, raw defaults, HW init), but not all drivers are using one of these. As a result, their implementation might currently depend on the zero-initialized cache or contain other workarounds. When reading an uninitialized value from the flat cache, warn the user, but maintain the current behavior. This will allow developers to switch to a sparse (flat) cache independently. Signed-off-by: Sander Vanheule Link: https://patch.msgid.link/20251029081248.52607-3-sander@svanheule.net Signed-off-by: Mark Brown --- drivers/base/regmap/regcache-flat.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/drivers/base/regmap/regcache-flat.c b/drivers/base/regmap/regcache-flat.c index 86f7679175b16..3b9235bb8313a 100644 --- a/drivers/base/regmap/regcache-flat.c +++ b/drivers/base/regmap/regcache-flat.c @@ -89,6 +89,11 @@ static int regcache_flat_read(struct regmap *map, struct regcache_flat_data *cache = map->cache; unsigned int index = regcache_flat_get_index(map, reg); + /* legacy behavior: ignore validity, but warn the user */ + if (unlikely(!test_bit(index, cache->valid))) + dev_warn_once(map->dev, + "using zero-initialized flat cache, this may cause unexpected behavior"); + *value = cache->data[index]; return 0; @@ -114,17 +119,6 @@ static int regcache_flat_write(struct regmap *map, unsigned int reg, struct regcache_flat_data *cache = map->cache; unsigned int index = regcache_flat_get_index(map, reg); - cache->data[index] = value; - - return 0; -} - -static int regcache_flat_sparse_write(struct regmap *map, unsigned int reg, - unsigned int value) -{ - struct regcache_flat_data *cache = map->cache; - unsigned int index = regcache_flat_get_index(map, reg); - cache->data[index] = value; __set_bit(index, cache->valid); @@ -158,6 +152,6 @@ struct regcache_ops regcache_flat_sparse_ops = { .init = regcache_flat_init, .exit = regcache_flat_exit, .read = regcache_flat_sparse_read, - .write = regcache_flat_sparse_write, + .write = regcache_flat_write, .drop = regcache_flat_drop, }; -- 2.47.3