Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934420Ab2HWU6f (ORCPT ); Thu, 23 Aug 2012 16:58:35 -0400 Received: from zose-mta15.web4all.fr ([176.31.217.11]:49502 "EHLO zose-mta15.web4all.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934358Ab2HWU6c convert rfc822-to-8bit (ORCPT ); Thu, 23 Aug 2012 16:58:32 -0400 Date: Thu, 23 Aug 2012 23:03:57 +0200 (CEST) From: =?utf-8?Q?Beno=C3=AEt_Th=C3=A9baudeau?= To: Thierry Reding , linux-kernel@vger.kernel.org, Sascha Hauer , linux-arm-kernel@lists.infradead.org Cc: Dmitry Torokhov , linux-input@vger.kernel.org, Bryan Wu , Richard Purdie , linux-leds@vger.kernel.org, Florian Tobias Schandinat , linux-fbdev@vger.kernel.org, Lars-Peter Clausen Message-ID: <1305545087.2775440.1345755837651.JavaMail.root@advansee.com> In-Reply-To: <20120823191108.GB8127@avionic-0098.mockup.avionic-design.de> Subject: [PATCH] pwm-imx: Fix config / enable / disable MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [88.188.188.98] X-Mailer: Zimbra 7.2.0_GA_2669 (ZimbraWebClient - FF3.0 (Win)/7.2.0_GA_2669) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3540 Lines: 121 imx_pwm_config() did not enable the PWM IP clock while accessing the registers. Hence, a call to pwm_config() had no effect before pwm_enable() had been called, which does not comply to the PWM API. Moreover, calling pwm_disable() then pwm_enable() must be a transparent operation. This fixes the first setting of brightness through sysfs that had no effect with leds-pwm. Cc: Thierry Reding Cc: Cc: Sascha Hauer Cc: Cc: Benoît Thébaudeau Signed-off-by: Benoît Thébaudeau --- .../drivers/pwm/pwm-imx.c | 55 +++++++++++++++----- 1 file changed, 43 insertions(+), 12 deletions(-) diff --git linux-next-c94456b.orig/drivers/pwm/pwm-imx.c linux-next-c94456b/drivers/pwm/pwm-imx.c index 2a0b353..0519bf2 100644 --- linux-next-c94456b.orig/drivers/pwm/pwm-imx.c +++ linux-next-c94456b/drivers/pwm/pwm-imx.c @@ -55,6 +55,16 @@ static int imx_pwm_config(struct pwm_chip *chip, { struct imx_chip *imx = to_imx_chip(chip); + /* + * If the PWM is disabled, make sure to turn on the clock before + * accessing the registers. + */ + if (!imx->clk_enabled) { + int rc = clk_prepare_enable(imx->clk); + if (rc) + return rc; + } + if (!(cpu_is_mx1() || cpu_is_mx21())) { unsigned long long c; unsigned long period_cycles, duty_cycles, prescale; @@ -85,8 +95,11 @@ static int imx_pwm_config(struct pwm_chip *chip, writel(period_cycles, imx->mmio_base + MX3_PWMPR); cr = MX3_PWMCR_PRESCALER(prescale) | - MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN | - MX3_PWMCR_DBGEN | MX3_PWMCR_EN; + MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN | MX3_PWMCR_DBGEN; + + /* If the PWM is enabled, keep it so. */ + if (imx->clk_enabled) + cr |= MX3_PWMCR_EN; if (cpu_is_mx25()) cr |= MX3_PWMCR_CLKSRC_IPG; @@ -118,32 +131,50 @@ static int imx_pwm_config(struct pwm_chip *chip, BUG(); } + /* If the PWM is disabled, turn the clock off again to save power. */ + if (!imx->clk_enabled) + clk_disable_unprepare(imx->clk); + return 0; } static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct imx_chip *imx = to_imx_chip(chip); - int rc = 0; + int rc; - if (!imx->clk_enabled) { - rc = clk_prepare_enable(imx->clk); - if (!rc) - imx->clk_enabled = 1; + if (imx->clk_enabled) + return 0; + + rc = clk_prepare_enable(imx->clk); + if (rc) + return rc; + + if (!(cpu_is_mx1() || cpu_is_mx21())) { + u32 cr = readl(imx->mmio_base + MX3_PWMCR); + cr |= MX3_PWMCR_EN; + writel(cr, imx->mmio_base + MX3_PWMCR); } - return rc; + + imx->clk_enabled = 1; + return 0; } static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct imx_chip *imx = to_imx_chip(chip); - writel(0, imx->mmio_base + MX3_PWMCR); + if (!imx->clk_enabled) + return; - if (imx->clk_enabled) { - clk_disable_unprepare(imx->clk); - imx->clk_enabled = 0; + if (!(cpu_is_mx1() || cpu_is_mx21())) { + u32 cr = readl(imx->mmio_base + MX3_PWMCR); + cr &= ~MX3_PWMCR_EN; + writel(cr, imx->mmio_base + MX3_PWMCR); } + + clk_disable_unprepare(imx->clk); + imx->clk_enabled = 0; } static struct pwm_ops imx_pwm_ops = { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/