regulator: return set_mode is same mode is requested

On Mon, 2010-05-17 at 17:34 +0200, Mark Brown wrote:
> This doesn't seem like the right error handling - if the driver has a
> set_mode() you'd *expect* it to have a get_mode() but there's no need
> for it to be a strict requirement.
True. In such a case, even a valid request would be lost! So now
in the updated patch:
 - check if get_mode is present to avoid oops;
 - if get_mode is not present, proceed anyways for the request.

Here is the updated patch:

>From bad0d5eb51ef84be5b100e3dd0f5a590ea0529b6 Mon Sep 17 00:00:00 2001
From: Sundar R Iyer <sundar.iyer@stericsson.com>
Date: Fri, 14 May 2010 15:14:17 +0530
Subject: [PATCH 1/1] regulator: return set_mode when same mode is requested

save I/O costs by returning when the same mode is
requested for the regulator

Cc: Liam Girdwood <lrg@slimlogic.co.uk>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Sundar R Iyer <sundar.iyer@stericsson.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 98e5d14f94f3..2248087b9be2 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1745,6 +1745,7 @@ int regulator_set_mode(struct regulator *regulator, unsigned int mode)
 {
         struct regulator_dev *rdev = regulator->rdev;
         int ret;
+        int regulator_curr_mode;
 
         mutex_lock(&rdev->mutex);
 
@@ -1754,6 +1755,15 @@ int regulator_set_mode(struct regulator *regulator, unsigned int mode)
                 goto out;
         }
 
+        /* return if the same mode is requested */
+        if (rdev->desc->ops->get_mode) {
+                regulator_curr_mode = rdev->desc->ops->get_mode(rdev);
+                if (regulator_curr_mode == mode) {
+                        ret = 0;
+                        goto out;
+                }
+        }
+
         /* constraints check */
         ret = regulator_check_mode(rdev, mode);
         if (ret < 0)