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regmap: Add missing cache_only checks

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The current behaviour around cache_only is slightly inconsistent,
most paths will only check cache_only if cache_bypass is false,
and will return -EBUSY if a read attempts to go to the hardware
whilst cache_only is true. However, a couple of paths will not check
cache_only at all.  The most notable of these being regmap_raw_read
which will check cache_only in the case it processes the transaction
one register at a time, but not in the case it handles them as a
block. In the typical case a device has been put into cache_only
whilst powered down this can cause physical reads to happen whilst the
device is unavailable.

Add a check in regmap_raw_read and move the check in regmap_noinc_read,
adding a check for cache_bypass, such that all paths are covered and
consistent.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230601101036.1499612-2-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Charles Keepax
2023-06-01 11:10:36 +01:00
committed by Mark Brown
parent 02534c8e96
commit 99e8dd39f3
1 changed files with 16 additions and 10 deletions
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26
drivers/base/regmap/regmap.c
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@@ -2981,6 +2981,11 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
size_t chunk_count, chunk_bytes;
size_t chunk_regs = val_count;
if (!map->cache_bypass && map->cache_only) {
ret = -EBUSY;
goto out;
}
if (!map->read) {
ret = -ENOTSUPP;
goto out;
@@ -3076,18 +3081,19 @@ int regmap_noinc_read(struct regmap *map, unsigned int reg,
goto out_unlock;
}
/*
* We have not defined the FIFO semantics for cache, as the
* cache is just one value deep. Should we return the last
* written value? Just avoid this by always reading the FIFO
* even when using cache. Cache only will not work.
*/
if (!map->cache_bypass && map->cache_only) {
ret = -EBUSY;
goto out_unlock;
}
/* Use the accelerated operation if we can */
if (map->bus->reg_noinc_read) {
/*
* We have not defined the FIFO semantics for cache, as the
* cache is just one value deep. Should we return the last
* written value? Just avoid this by always reading the FIFO
* even when using cache. Cache only will not work.
*/
if (map->cache_only) {
ret = -EBUSY;
goto out_unlock;
}
ret = regmap_noinc_readwrite(map, reg, val, val_len, false);
goto out_unlock;
}