linux-kernel - Applied "regulator: pwm-regulator: Simplify voltage to duty-cycle call" to the regulator tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <E1ZCXe0-0001W1-V0@debutante>
Date:	Tue, 07 Jul 2015 19:31:00 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Lee Jones <lee.jones@...aro.org>, Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Applied "regulator: pwm-regulator: Simplify voltage to duty-cycle call" to the regulator tree

The patch

   regulator: pwm-regulator: Simplify voltage to duty-cycle call

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From cae897dec26a9d81dcb5182b13b08450f38d6bde Mon Sep 17 00:00:00 2001
From: Lee Jones <lee.jones@...aro.org>
Date: Tue, 7 Jul 2015 16:06:52 +0100
Subject: [PATCH] regulator: pwm-regulator: Simplify voltage to duty-cycle call

If we reverse some of the logic and change the formula used,
we can simplify the function greatly.

It is intentional that this function is supplied and then re-worked
within the same patch-set.  The submission in the previous patch is
the tried and tested (i.e. in real releases) method written by ST.
This patch contains a simplification provided later.  It looks and
performs better, but doesn't have the same time-under-test that the
original method does.  The idea is that we keep some history in
order to provide an easy way back i.e. revert.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/regulator/pwm-regulator.c | 27 +++++++--------------------
 1 file changed, 7 insertions(+), 20 deletions(-)

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index dac145db305c..d5cb267fa192 100644
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -93,26 +93,13 @@ static int pwm_regulator_list_voltage(struct regulator_dev *rdev,
 /**
  * Continuous voltage call-backs
  */
-static int pwm_voltage_to_duty_cycle(struct regulator_dev *rdev,
-					int volt_mV)
+static int pwm_voltage_to_duty_cycle(struct regulator_dev *rdev, int req_uV)
 {
-	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
-	int min_mV = rdev->constraints->min_uV / 1000;
-	int max_mV = rdev->constraints->max_uV / 1000;
-	int max_duty_cycle = drvdata->max_duty_cycle;
-	int vdiff = min_mV - max_mV;
-	int pwm_code;
-	int tmp;
-
-	tmp = ((max_duty_cycle - min_mV) * max_duty_cycle) / vdiff;
-	pwm_code = ((tmp + max_duty_cycle) * volt_mV) / vdiff;
-
-	if (pwm_code < 0)
-		pwm_code = 0;
-	if (pwm_code > max_duty_cycle)
-		pwm_code = max_duty_cycle;
-
-	return pwm_code * 100 / max_duty_cycle;
+	int min_uV = rdev->constraints->min_uV;
+	int max_uV = rdev->constraints->max_uV;
+	int diff = max_uV - min_uV;
+
+	return 100 - ((((req_uV * 100) - (min_uV * 100)) / diff));
 }

 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
@@ -131,7 +118,7 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
 	int duty_cycle;
 	int ret;

-	duty_cycle = pwm_voltage_to_duty_cycle(rdev, min_uV / 1000);
+	duty_cycle = pwm_voltage_to_duty_cycle(rdev, min_uV);

 	ret = pwm_config(drvdata->pwm,
 			 (drvdata->pwm->period / 100) * duty_cycle,
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/