linux-kernel - RE: [PATCH v2] regulator: ad5398: Fix min/max current limit boundary checking

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Message-ID: <DB904C5425BA6F4E8424B3B51A1414D17140805D85@NWD2CMBX1.ad.analog.com>
Date:	Tue, 3 Jul 2012 03:54:55 -0400
From:	"Zhang, Sonic" <Sonic.Zhang@...log.com>
To:	Axel Lin <axel.lin@...il.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Liam Girdwood <lrg@...com>
Subject: RE: [PATCH v2] regulator: ad5398: Fix min/max current limit
 boundary checking



>-----Original Message-----
>From: Axel Lin [mailto:axel.lin@...il.com]
>Sent: Tuesday, July 03, 2012 3:43 PM
>To: Mark Brown
>Cc: linux-kernel@...r.kernel.org; Zhang, Sonic; Lars-Peter Clausen; Liam
>Girdwood
>Subject: [PATCH v2] regulator: ad5398: Fix min/max current limit boundary
>checking
>
>It is ok to request current limit with min_uA < chip->min_uA and
>max_uA > chip->max_uA.
>
>We need to set min_uA = chip->min_uA if (min_uA < chip->min_uA),
>this ensures the equation to calcuate selator does not return negative number.
>

You should not do it in driver. Set a correct min_uA value in your application.

Regards,

Sonic

>Signed-off-by: Axel Lin <axel.lin@...il.com>
>~
>---
> drivers/regulator/ad5398.c |    7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/regulator/ad5398.c b/drivers/regulator/ad5398.c
>index 46d05f3..84fdcda 100644
>--- a/drivers/regulator/ad5398.c
>+++ b/drivers/regulator/ad5398.c
>@@ -89,9 +89,10 @@ static int ad5398_set_current_limit(struct regulator_dev
>*rdev, int min_uA, int
>       unsigned short data;
>       int ret;
>
>-      if (min_uA > chip->max_uA || min_uA < chip->min_uA)
>-              return -EINVAL;
>-      if (max_uA > chip->max_uA || max_uA < chip->min_uA)
>+      if (min_uA < chip->min_uA)
>+              min_uA = chip->min_uA;
>+
>+      if (min_uA > chip->max_uA || max_uA < chip->min_uA)
>               return -EINVAL;
>
>       selector = DIV_ROUND_UP((min_uA - chip->min_uA) * chip->current_level,
>--
>1.7.9.5
>
>
>