regmap: Only send a single buffer for async I/O if writing one register

Extend the interface for async I/O by allowing the value buffer to be
omitted and sending the value as part of the register buffer, minimising
the number of separate hardware operations required.

Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index a975a601f718..d0ce2fef43a3 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1157,18 +1157,23 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
                 /* If the caller supplied the value we can use it safely. */
                 memcpy(async->work_buf, map->work_buf, map->format.pad_bytes +
                        map->format.reg_bytes + map->format.val_bytes);
-                if (val == work_val)
-                        val = async->work_buf + map->format.pad_bytes +
-                                map->format.reg_bytes;
 
                 spin_lock_irqsave(&map->async_lock, flags);
                 list_add_tail(&async->list, &map->async_list);
                 spin_unlock_irqrestore(&map->async_lock, flags);
 
-                ret = map->bus->async_write(map->bus_context, async->work_buf,
-                                            map->format.reg_bytes +
-                                            map->format.pad_bytes,
-                                            val, val_len, async);
+                if (val != work_val)
+                        ret = map->bus->async_write(map->bus_context,
+                                                    async->work_buf,
+                                                    map->format.reg_bytes +
+                                                    map->format.pad_bytes,
+                                                    val, val_len, async);
+                else
+                        ret = map->bus->async_write(map->bus_context,
+                                                    async->work_buf,
+                                                    map->format.reg_bytes +
+                                                    map->format.pad_bytes +
+                                                    val_len, NULL, 0, async);
 
                 if (ret != 0) {
                         dev_err(map->dev, "Failed to schedule write: %d\n",