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Subject[PATCH 2/2] regmap: cache: Fall back to register by register read for cache defaults
Date
From: Mark Brown <broonie@kernel.org>

If we are unable to read the cache defaults for a regmap then fall back
on attempting to read them word by word. This is going to be painfully
slow for large regmaps but might be adequate for smaller ones.

Signed-off-by: Mark Brown <broonie@kernel.org>
[maciej: Use cache_bypass around read and skipping of unreadable regs]
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
---
drivers/base/regmap/regcache.c | 41 ++++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 5c5090b..4170b7d 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -30,7 +30,7 @@ static int regcache_hw_init(struct regmap *map)
int i, j;
int ret;
int count;
- unsigned int val;
+ unsigned int reg, val;
void *tmp_buf;

if (!map->num_reg_defaults_raw)
@@ -67,27 +67,46 @@ static int regcache_hw_init(struct regmap *map)
ret = regmap_raw_read(map, 0, tmp_buf,
map->cache_size_raw);
map->cache_bypass = cache_bypass;
- if (ret < 0)
- goto err_cache_free;
-
- map->reg_defaults_raw = tmp_buf;
- map->cache_free = 1;
+ if (ret == 0) {
+ map->reg_defaults_raw = tmp_buf;
+ map->cache_free = 1;
+ } else {
+ kfree(tmp_buf);
+ }
}

/* fill the reg_defaults */
for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
- if (regmap_volatile(map, i * map->reg_stride))
+ reg = i * map->reg_stride;
+
+ if (!regmap_readable(map, reg))
continue;
- val = regcache_get_val(map, map->reg_defaults_raw, i);
- map->reg_defaults[j].reg = i * map->reg_stride;
+
+ if (regmap_volatile(map, reg))
+ continue;
+
+ if (map->reg_defaults_raw) {
+ val = regcache_get_val(map, map->reg_defaults_raw, i);
+ } else {
+ bool cache_bypass = map->cache_bypass;
+
+ map->cache_bypass = true;
+ ret = regmap_read(map, reg, &val);
+ map->cache_bypass = cache_bypass;
+ if (ret != 0) {
+ dev_err(map->dev, "Failed to read %d: %d\n",
+ reg, ret);
+ goto err_free;
+ }
+ }
+
+ map->reg_defaults[j].reg = reg;
map->reg_defaults[j].def = val;
j++;
}

return 0;

-err_cache_free:
- kfree(tmp_buf);
err_free:
kfree(map->reg_defaults);

--
1.9.1
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