From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756444AbcJYFz3 (ORCPT ); Tue, 25 Oct 2016 01:55:29 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:58486 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754721AbcJYFz1 (ORCPT ); Tue, 25 Oct 2016 01:55:27 -0400 Date: Tue, 25 Oct 2016 07:54:54 +0200 From: Sascha Hauer To: Lukasz Majewski Cc: Thierry Reding , Stefan Agner , Boris Brezillon , linux-pwm@vger.kernel.org, Bhuvanchandra DV , linux-kernel@vger.kernel.org, kernel@pengutronix.de, Fabio Estevam , Fabio Estevam , Lothar Wassmann Subject: Re: [PATCH 1/6] pwm: imx: Rewrite imx_pwm_*_v1 code to facilitate switch to atomic pwm operation Message-ID: <20161025055454.emytytmcg6d23jdd@pengutronix.de> References: <1477259146-19167-1-git-send-email-l.majewski@majess.pl> <1477259146-19167-2-git-send-email-l.majewski@majess.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1477259146-19167-2-git-send-email-l.majewski@majess.pl> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 07:49:14 up 152 days, 16:13, 21 users, load average: 0.01, 0.03, 0.05 User-Agent: Mutt/1.6.2-neo (2016-06-11) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 23, 2016 at 11:45:41PM +0200, Lukasz Majewski wrote: > The code has been rewritten to remove "generic" calls to > imx_pwm_{enable|disable|config}. > > Such approach would facilitate switch to atomic PWM (a.k.a ->apply()) > implementation. > > Suggested-by: Stefan Agner > Suggested-by: Boris Brezillon > Signed-off-by: Lukasz Majewski > --- > drivers/pwm/pwm-imx.c | 46 ++++++++++++++++++++++++++++++++++------------ > 1 file changed, 34 insertions(+), 12 deletions(-) > > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c > index c37d223..83e43d5 100644 > --- a/drivers/pwm/pwm-imx.c > +++ b/drivers/pwm/pwm-imx.c > @@ -66,8 +66,6 @@ struct imx_chip { > static int imx_pwm_config_v1(struct pwm_chip *chip, > struct pwm_device *pwm, int duty_ns, int period_ns) > { > - struct imx_chip *imx = to_imx_chip(chip); > - > /* > * The PWM subsystem allows for exact frequencies. However, > * I cannot connect a scope on my device to the PWM line and > @@ -85,26 +83,52 @@ static int imx_pwm_config_v1(struct pwm_chip *chip, > * both the prescaler (/1 .. /128) and then by CLKSEL > * (/2 .. /16). > */ > + struct imx_chip *imx = to_imx_chip(chip); > u32 max = readl(imx->mmio_base + MX1_PWMP); > u32 p = max * duty_ns / period_ns; > + int ret; > + > + ret = clk_prepare_enable(imx->clk_ipg); > + if (ret) > + return ret; > + > writel(max - p, imx->mmio_base + MX1_PWMS); > > + clk_disable_unprepare(imx->clk_ipg); > + > return 0; > } > > -static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable) > +static int imx_pwm_enable_v1(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct imx_chip *imx = to_imx_chip(chip); > + int ret; > u32 val; > > + ret = clk_prepare_enable(imx->clk_ipg); > + if (ret) > + return ret; > + > val = readl(imx->mmio_base + MX1_PWMC); > + val |= MX1_PWMC_EN; > + writel(val, imx->mmio_base + MX1_PWMC); > > - if (enable) > - val |= MX1_PWMC_EN; > - else > - val &= ~MX1_PWMC_EN; > + clk_disable_unprepare(imx->clk_per); This looks wrong. You start by enabling clk_ipg which is needed for register access, but then end with disabling clk_per which is needed for driving the actual PWM output. This function should probably enable clk_per on entry and enable clk_ipg while accessing registers. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |