mfd: Use bulk read to fill WM8350 register cache
Mark Brown [Wed, 4 Feb 2009 21:43:55 +0000 (22:43 +0100)]
Some I2C controllers have high overheads for setting up I2C operations
which makes the register cache setup on startup excessively slow since
it does a lot of small transactions. Reduce this overhead by doing a
bulk read of the entire register bank and filtering out what we don't
need later.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>

drivers/mfd/wm8350-core.c

index b457a05..f22b18b 100644 (file)
@@ -1238,7 +1238,7 @@ static int wm8350_create_cache(struct wm8350 *wm8350, int type, int mode)
        }
 
        wm8350->reg_cache =
-           kzalloc(sizeof(u16) * (WM8350_MAX_REGISTER + 1), GFP_KERNEL);
+               kmalloc(sizeof(u16) * (WM8350_MAX_REGISTER + 1), GFP_KERNEL);
        if (wm8350->reg_cache == NULL)
                return -ENOMEM;
 
@@ -1246,17 +1246,20 @@ static int wm8350_create_cache(struct wm8350 *wm8350, int type, int mode)
         * a PMIC so the device many not be in a virgin state and we
         * can't rely on the silicon values.
         */
+       ret = wm8350->read_dev(wm8350, 0,
+                              sizeof(u16) * (WM8350_MAX_REGISTER + 1),
+                              wm8350->reg_cache);
+       if (ret < 0) {
+               dev_err(wm8350->dev,
+                       "failed to read initial cache values\n");
+               goto out;
+       }
+
+       /* Mask out uncacheable/unreadable bits and the audio. */
        for (i = 0; i < WM8350_MAX_REGISTER; i++) {
-               /* audio register range */
                if (wm8350_reg_io_map[i].readable &&
                    (i < WM8350_CLOCK_CONTROL_1 || i > WM8350_AIF_TEST)) {
-                       ret = wm8350->read_dev(wm8350, i, 2, (char *)&value);
-                       if (ret < 0) {
-                               dev_err(wm8350->dev,
-                                      "failed to read initial cache value\n");
-                               goto out;
-                       }
-                       value = be16_to_cpu(value);
+                       value = be16_to_cpu(wm8350->reg_cache[i]);
                        value &= wm8350_reg_io_map[i].readable;
                        value &= ~wm8350_reg_io_map[i].vol;
                        wm8350->reg_cache[i] = value;