linux-kernel - [PATCH] backlight: aat2870: fix setting max

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Date:	Wed, 06 Jul 2011 16:41:05 +0800
From:	Axel Lin <axel.lin@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Jin Park <jinyoungp@...dia.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] backlight: aat2870: fix setting max_current

1. current implementation tests wrong value for setting aat2870_bl->max_current.
2. In current implementation, we cannot differentiate below 2 cases:
       a) if pdata->max_current is not set , or
       b) pdata->max_current is set to AAT2870_CURRENT_0_45 ( which is also 0 ).
   fix it by setting AAT2870_CURRENT_0_45 to be 1 and adjust the equation
   in aat2870_brightness() accordingly.

Signed-off-by: Axel Lin <axel.lin@...il.com>
---
hi Jin,
I make enum aat2870_current starting from 1 instead of adding a AAT2870_CURRENT_0_00,
because adding a AAT2870_CURRENT_0_00 may let people feel it is a valid setting for max_current.

BTW, I don't have this device handy. can you help to test it?
Thanks,
Axel

 drivers/video/backlight/aat2870_bl.c |    4 ++--
 include/linux/mfd/aat2870.h          |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/aat2870_bl.c b/drivers/video/backlight/aat2870_bl.c
index 4952a61..c0e2ce7 100644
--- a/drivers/video/backlight/aat2870_bl.c
+++ b/drivers/video/backlight/aat2870_bl.c
@@ -44,7 +44,7 @@ static inline int aat2870_brightness(struct aat2870_bl_driver_data *aat2870_bl,
 	struct backlight_device *bd = aat2870_bl->bd;
 	int val;
 
-	val = brightness * aat2870_bl->max_current;
+	val = brightness * (aat2870_bl->max_current - 1);
 	val /= bd->props.max_brightness;
 
 	return val;
@@ -175,7 +175,7 @@ static int aat2870_bl_probe(struct platform_device *pdev)
 	else
 		aat2870_bl->channels = AAT2870_BL_CH_ALL;
 
-	if (pdata->max_brightness > 0)
+	if (pdata->max_current > 0)
 		aat2870_bl->max_current = pdata->max_current;
 	else
 		aat2870_bl->max_current = AAT2870_CURRENT_27_9;
diff --git a/include/linux/mfd/aat2870.h b/include/linux/mfd/aat2870.h
index 89212df..f7316c2 100644
--- a/include/linux/mfd/aat2870.h
+++ b/include/linux/mfd/aat2870.h
@@ -89,7 +89,7 @@ enum aat2870_id {
 
 /* Backlight current magnitude (mA) */
 enum aat2870_current {
-	AAT2870_CURRENT_0_45,
+	AAT2870_CURRENT_0_45 = 1,
 	AAT2870_CURRENT_0_90,
 	AAT2870_CURRENT_1_80,
 	AAT2870_CURRENT_2_70,
-- 
1.7.4.1



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