Re: [PATCH 2/2] regmap: cache: Fall back to register by register read for cache defaults

[Maciej S. Szmigiero]

On 01.02.2016 23:13, Mark Brown wrote:
> On Mon, Feb 01, 2016 at 07:58:54PM -0200, Fabio Estevam wrote:
>> On Mon, Feb 1, 2016 at 7:41 PM, Mark Brown <broo...@kernel.org> wrote:
>>> On Mon, Feb 01, 2016 at 09:38:15PM +0000, Mark Brown wrote:
>>>> 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.
> 
>>> Competely untested, hopefully it helps fix the issues with the SSI.
> 
>> After applying this series I get:
> 
> Please try to fix it yourself, probably needs setting cache_bypass
> around the manual fill.

Thanks for patches.

I was able to make SSI work again after modifying second patch
with cache_bypass around read and skipping of unreadable regs:
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);