From: Brian Norris <briannorris@chromium.org>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
linux-pwm@vger.kernel.org, Mark Brown <broonie@kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>,
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>,
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
Subject: Re: [PATCH 05/14] pwm: rockchip: Avoid glitches on already running PWMs
Date: Fri, 3 Jun 2016 13:28:59 -0700 [thread overview]
Message-ID: <20160603202859.GD124478@google.com> (raw)
In-Reply-To: <1464942192-25967-6-git-send-email-boris.brezillon@free-electrons.com>
Hi,
Just noticed a few things:
On Fri, Jun 03, 2016 at 10:23:03AM +0200, Boris Brezillon wrote:
> 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)
Why not just if (!pwm_is_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)
Same here.
With that:
Reviewed-by: Brian Norris <briannorris@chromium.org>
And it tests out fine:
Tested-by: Brian Norris <briannorris@chromium.org>
> + clk_disable(pc->clk);
>
> clk_unprepare(pc->clk);
>
> --
> 2.7.4
>
next prev parent reply other threads:[~2016-06-03 20:28 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 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
[not found] ` <1464942192-25967-1-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
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 05/14] pwm: rockchip: Avoid glitches on already running PWMs Boris Brezillon
2016-06-03 20:28 ` Brian Norris [this message]
2016-06-04 6:26 ` Boris Brezillon
2016-06-03 8:23 ` [PATCH 07/14] pwm: sti: Add support for hardware readout Boris Brezillon
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 06/14] pwm: rockchip: Add support for atomic update Boris Brezillon
[not found] ` <1464942192-25967-7-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 20:37 ` Brian Norris
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
[not found] ` <1464942192-25967-11-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
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 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
[not found] ` <1464942192-25967-15-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 21:04 ` Brian Norris
2016-06-06 14:09 ` Rob Herring
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