From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Thierry Reding <thierry.reding@gmail.com>,
linux-pwm@vger.kernel.org, Mark Brown <broonie@kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>
Cc: Heiko Stuebner <heiko@sntech.de>,
linux-rockchip@lists.infradead.org,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Milo Kim <milo.kim@ti.com>,
Doug Anderson <dianders@google.com>,
Caesar Wang <wxt@rock-chips.com>,
Stephen Barber <smbarber@chromium.org>,
Brian Norris <briannorris@chromium.org>,
Ajit Pal Singh <ajitpal.singh@st.com>,
Srinivas Kandagatla <srinivas.kandagatla@gmail.com>,
Maxime Coquelin <maxime.coquelin@st.com>,
Patrice Chotard <patrice.chotard@st.com>,
kernel@stlinux.com,
Boris Brezillon <boris.brezillon@free-electrons.com>
Subject: [PATCH 05/14] pwm: rockchip: Avoid glitches on already running PWMs
Date: Fri, 3 Jun 2016 10:23:03 +0200 [thread overview]
Message-ID: <1464942192-25967-6-git-send-email-boris.brezillon@free-electrons.com> (raw)
In-Reply-To: <1464942192-25967-1-git-send-email-boris.brezillon@free-electrons.com>
The current logic will disable the PWM clk even if the PWM was left
enabled by the bootloader (because it's controlling a critical device
like a regulator for example).
Keep the PWM clk enabled if the PWM is enabled to avoid any glitches.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/pwm/pwm-rockchip.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index dfacf7d..798a787 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -299,6 +299,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
{
const struct of_device_id *id;
struct rockchip_pwm_chip *pc;
+ struct pwm_state state;
struct resource *r;
int ret;
@@ -319,7 +320,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
if (IS_ERR(pc->clk))
return PTR_ERR(pc->clk);
- ret = clk_prepare(pc->clk);
+ ret = clk_prepare_enable(pc->clk);
if (ret)
return ret;
@@ -342,12 +343,33 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
}
+ /* Keep the PWM clk enabled if the PWM appears to be up and running. */
+ pwm_get_state(pc->chip.pwms, &state);
+ if (!state.enabled)
+ clk_disable(pc->clk);
+
return ret;
}
static int rockchip_pwm_remove(struct platform_device *pdev)
{
struct rockchip_pwm_chip *pc = platform_get_drvdata(pdev);
+ struct pwm_state state;
+
+ /*
+ * Disable the PWM clk before unpreparing it if the PWM device is still
+ * running. This should only happen when the last PWM user left it
+ * enabled, or when nobody requested a PWM that was previously enabled
+ * by the bootloader.
+ *
+ * FIXME: Maybe the core should disable all PWM devices in
+ * pwmchip_remove(). In this case we'd only have to call
+ * clk_unprepare() after pwmchip_remove().
+ *
+ */
+ pwm_get_state(pc->chip.pwms, &state);
+ if (state.enabled)
+ clk_disable(pc->clk);
clk_unprepare(pc->clk);
--
2.7.4
next prev parent reply other threads:[~2016-06-03 8:27 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-03 8:22 [PATCH 00/14] regulator: pwm: various improvements Boris Brezillon
2016-06-03 8:22 ` [PATCH 01/14] pwm: Add new helpers to create/manipulate PWM states Boris Brezillon
2016-06-03 8:23 ` [PATCH 02/14] regulator: pwm: Drop unneeded pwm_enable() call Boris Brezillon
2016-06-03 11:08 ` Applied "regulator: pwm: Drop unneeded pwm_enable() call" to the regulator tree Mark Brown
2016-06-03 8:23 ` [PATCH 03/14] pwm: rockchip: Fix period and duty_cycle approximation Boris Brezillon
2016-06-03 20:03 ` Brian Norris
2016-06-04 6:19 ` Boris Brezillon
2016-06-07 17:25 ` Brian Norris
2016-06-03 8:23 ` [PATCH 04/14] pwm: rockchip: Add support for hardware readout Boris Brezillon
2016-06-03 20:07 ` Brian Norris
2016-06-03 20:20 ` Brian Norris
2016-06-04 6:24 ` Boris Brezillon
2016-06-07 17:26 ` Brian Norris
2016-06-03 8:23 ` Boris Brezillon [this message]
2016-06-03 20:28 ` [PATCH 05/14] pwm: rockchip: Avoid glitches on already running PWMs Brian Norris
2016-06-04 6:26 ` Boris Brezillon
2016-06-03 8:23 ` [PATCH 06/14] pwm: rockchip: Add support for atomic update Boris Brezillon
2016-06-03 20:37 ` Brian Norris
2016-06-03 8:23 ` [PATCH 07/14] pwm: sti: Add support for hardware readout Boris Brezillon
2016-06-03 8:23 ` [PATCH 08/14] pwm: sti: Avoid glitches on already running PWMs Boris Brezillon
2016-06-03 20:38 ` Brian Norris
2016-06-03 8:23 ` [PATCH 09/14] regulator: pwm: Adjust PWM config at probe time Boris Brezillon
2016-06-03 20:41 ` Brian Norris
2016-06-03 8:23 ` [PATCH 10/14] regulator: pwm: Switch to the atomic PWM API Boris Brezillon
2016-06-03 20:50 ` Brian Norris
2016-06-04 6:28 ` Boris Brezillon
2016-06-06 6:14 ` Laxman Dewangan
2016-06-03 8:23 ` [PATCH 11/14] regulator: pwm: properly initialize the ->state field Boris Brezillon
2016-06-03 20:51 ` Brian Norris
2016-06-03 8:23 ` [PATCH 12/14] regulator: pwm: Retrieve correct voltage Boris Brezillon
2016-06-03 20:55 ` Brian Norris
2016-06-03 8:23 ` [PATCH 13/14] regulator: pwm: Support extra continuous mode cases Boris Brezillon
2016-06-03 21:03 ` Brian Norris
2016-06-04 6:30 ` Boris Brezillon
2016-06-03 8:23 ` [PATCH 14/14] regulator: pwm: Document pwm-dutycycle-unit and pwm-dutycycle-range Boris Brezillon
2016-06-03 21:04 ` Brian Norris
2016-06-06 14:09 ` Rob Herring
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=1464942192-25967-6-git-send-email-boris.brezillon@free-electrons.com \
--to=boris.brezillon@free-electrons.com \
--cc=ajitpal.singh@st.com \
--cc=briannorris@chromium.org \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=dianders@google.com \
--cc=galak@codeaurora.org \
--cc=heiko@sntech.de \
--cc=ijc+devicetree@hellion.org.uk \
--cc=kernel@stlinux.com \
--cc=lgirdwood@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maxime.coquelin@st.com \
--cc=milo.kim@ti.com \
--cc=patrice.chotard@st.com \
--cc=pawel.moll@arm.com \
--cc=robh+dt@kernel.org \
--cc=smbarber@chromium.org \
--cc=srinivas.kandagatla@gmail.com \
--cc=thierry.reding@gmail.com \
--cc=wxt@rock-chips.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).