From 4b05ccb17f92268384d483221a577fccfc291c7a Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Wed, 5 Aug 2026 16:22:50 +0300 Subject: [PATCH] regcache: Sort the local copy of an unsorted reg_defaults array regcache_lookup_reg() bsearch()es the reg_defaults array, which requires it to be sorted by ascending register address. Entries following a descending step are never found, so regcache_reg_needs_sync() reports that they need a sync and they are written to the device on every regcache_sync() even when they were never touched. Detect the misordering while reg_defaults is validated against the register stride and sort the local copy. The check needs no new loop and sort() only runs for the affected drivers, which are also warned about. Note that sort() is not stable, so for arrays with duplicated register addresses it remains unspecified which entry is found. Signed-off-by: Peter Ujfalusi Reviewed-by: Charles Keepax Tested-by: Charles Keepax Link: https://patch.msgid.link/20260805132250.2637-1-peter.ujfalusi@linux.intel.com Signed-off-by: Mark Brown --- drivers/base/regmap/regcache.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c index 480bc76f9a02..623db7a1f3bd 100644 --- a/drivers/base/regmap/regcache.c +++ b/drivers/base/regmap/regcache.c @@ -123,6 +123,8 @@ static void regcache_hw_exit(struct regmap *map) int regcache_init(struct regmap *map, const struct regmap_config *config) { + bool sort_defaults = false; + unsigned int reg_prev = 0; int count = 0; int ret; int i; @@ -149,10 +151,16 @@ int regcache_init(struct regmap *map, const struct regmap_config *config) return -EINVAL; } - for (i = 0; i < config->num_reg_defaults; i++) + for (i = 0; i < config->num_reg_defaults; i++) { if (config->reg_defaults[i].reg % map->reg_stride) return -EINVAL; + if (reg_prev > config->reg_defaults[i].reg) + sort_defaults = true; + + reg_prev = config->reg_defaults[i].reg; + } + for (i = 0; i < ARRAY_SIZE(cache_types); i++) if (cache_types[i]->type == map->cache_type) break; @@ -186,6 +194,13 @@ int regcache_init(struct regmap *map, const struct regmap_config *config) sizeof(*map->reg_defaults), GFP_KERNEL); if (!tmp_buf) return -ENOMEM; + + /* regcache_lookup_reg() bsearch()es this array */ + if (sort_defaults) { + dev_warn(map->dev, + "Driver needs fixing: Unsorted reg_defaults, sorting the copy\n"); + regcache_sort_defaults(tmp_buf, map->num_reg_defaults); + } map->reg_defaults = tmp_buf; } else if (map->num_reg_defaults_raw) { count = regcache_count_cacheable_registers(map);