devicetree.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Fabrice Gasnier <fabrice.gasnier@st.com>
To: lee.jones@linaro.org, thierry.reding@gmail.com,
	robh+dt@kernel.org, alexandre.torgue@st.com,
	benjamin.gaignard@linaro.org
Cc: mark.rutland@arm.com, linux@armlinux.org.uk,
	mcoquelin.stm32@gmail.com, fabrice.gasnier@st.com,
	benjamin.gaignard@st.com, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org
Subject: [PATCH v2 2/8] pwm: stm32: protect common prescaler for all channels
Date: Fri, 26 Jan 2018 16:11:33 +0100	[thread overview]
Message-ID: <1516979499-3665-3-git-send-email-fabrice.gasnier@st.com> (raw)
In-Reply-To: <1516979499-3665-1-git-send-email-fabrice.gasnier@st.com>

There may be a race, when configuring two pwm channels, with different
prescaler values, when there's no active channel yet.
Add mutex lock to avoid concurrent access on pwm apply state.
This is also precursor patch for pwm capture support.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/pwm/pwm-stm32.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index 59524f9..3ac55df 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -21,6 +21,7 @@
 
 struct stm32_pwm {
 	struct pwm_chip chip;
+	struct mutex lock; /* protect pwm config/enable */
 	struct clk *clk;
 	struct regmap *regmap;
 	u32 max_arr;
@@ -213,9 +214,23 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
+static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm,
+				  struct pwm_state *state)
+{
+	struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
+	int ret;
+
+	/* protect common prescaler for all active channels */
+	mutex_lock(&priv->lock);
+	ret = stm32_pwm_apply(chip, pwm, state);
+	mutex_unlock(&priv->lock);
+
+	return ret;
+}
+
 static const struct pwm_ops stm32pwm_ops = {
 	.owner = THIS_MODULE,
-	.apply = stm32_pwm_apply,
+	.apply = stm32_pwm_apply_locked,
 };
 
 static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
@@ -335,6 +350,7 @@ static int stm32_pwm_probe(struct platform_device *pdev)
 	if (!priv)
 		return -ENOMEM;
 
+	mutex_init(&priv->lock);
 	priv->regmap = ddata->regmap;
 	priv->clk = ddata->clk;
 	priv->max_arr = ddata->max_arr;
-- 
1.9.1

  parent reply	other threads:[~2018-01-26 15:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-26 15:11 [PATCH v2 0/8] Add support for PWM input capture on STM32 Fabrice Gasnier
2018-01-26 15:11 ` [PATCH v2 1/8] pwm: stm32: fix, remove unused struct device Fabrice Gasnier
2018-01-26 15:11 ` Fabrice Gasnier [this message]
2018-01-26 15:11 ` [PATCH v2 3/8] dt-bindings: mfd: stm32-timers: add support for dmas Fabrice Gasnier
2018-02-05  6:07   ` Rob Herring
2018-01-26 15:11 ` [PATCH v2 4/8] " Fabrice Gasnier
2018-01-26 15:11 ` [PATCH v2 5/8] pwm: stm32: add capture support Fabrice Gasnier
2018-01-26 15:11 ` [PATCH v2 6/8] pwm: stm32: improve capture by tuning counter prescaler Fabrice Gasnier
2018-01-26 15:11 ` [PATCH v2 7/8] pwm: stm32: use input prescaler to improve period capture Fabrice Gasnier
2018-01-26 15:11 ` [PATCH v2 8/8] ARM: dts: stm32: Enable pwm3 input capture on stm32f429i-eval Fabrice Gasnier
2018-01-30 10:15 ` [PATCH v2 0/8] Add support for PWM input capture on STM32 Benjamin Gaignard
2018-02-14  8:23 ` Fabrice Gasnier
     [not found]   ` <5ade7f05-f5cc-e272-842c-22effa78b716-qxv4g6HH51o@public.gmane.org>
2018-02-14  9:38     ` Lee Jones

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1516979499-3665-3-git-send-email-fabrice.gasnier@st.com \
    --to=fabrice.gasnier@st.com \
    --cc=alexandre.torgue@st.com \
    --cc=benjamin.gaignard@linaro.org \
    --cc=benjamin.gaignard@st.com \
    --cc=devicetree@vger.kernel.org \
    --cc=lee.jones@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pwm@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=mark.rutland@arm.com \
    --cc=mcoquelin.stm32@gmail.com \
    --cc=robh+dt@kernel.org \
    --cc=thierry.reding@gmail.com \
    --subject='Re: [PATCH v2 2/8] pwm: stm32: protect common prescaler for all channels' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).