From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Norris Subject: Re: [PATCH 05/14] pwm: rockchip: Avoid glitches on already running PWMs Date: Fri, 3 Jun 2016 13:28:59 -0700 Message-ID: <20160603202859.GD124478@google.com> References: <1464942192-25967-1-git-send-email-boris.brezillon@free-electrons.com> <1464942192-25967-6-git-send-email-boris.brezillon@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1464942192-25967-6-git-send-email-boris.brezillon@free-electrons.com> Sender: linux-pwm-owner@vger.kernel.org To: Boris Brezillon Cc: Thierry Reding , linux-pwm@vger.kernel.org, Mark Brown , Liam Girdwood , Heiko Stuebner , linux-rockchip@lists.infradead.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Milo Kim , Doug Anderson , Caesar Wang , Stephen Barber , Ajit Pal Singh , Srinivas Kandagatla , Maxime Coquelin , Patrice Chotard , kernel@stlinux.com List-Id: devicetree@vger.kernel.org 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 > --- > 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 And it tests out fine: Tested-by: Brian Norris > + clk_disable(pc->clk); > > clk_unprepare(pc->clk); > > -- > 2.7.4 >