From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris Brezillon) Date: Tue, 14 Jun 2016 11:13:13 +0200 Subject: [PATCH v3 05/14] pwm: rockchip: Avoid glitches on already running PWMs In-Reply-To: <1465895602-31008-1-git-send-email-boris.brezillon@free-electrons.com> References: <1465895602-31008-1-git-send-email-boris.brezillon@free-electrons.com> Message-ID: <1465895602-31008-6-git-send-email-boris.brezillon@free-electrons.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Reviewed-by: Brian Norris Tested-by: Brian Norris Tested-by: Heiko Stuebner --- drivers/pwm/pwm-rockchip.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c index c72b419..dd8ca86 100644 --- a/drivers/pwm/pwm-rockchip.c +++ b/drivers/pwm/pwm-rockchip.c @@ -319,7 +319,7 @@ 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; @@ -342,6 +342,10 @@ 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. */ + if (!pwm_is_enabled(pc->chip.pwms)) + clk_disable(pc->clk); + return ret; } @@ -349,6 +353,20 @@ static int rockchip_pwm_remove(struct platform_device *pdev) { struct rockchip_pwm_chip *pc = platform_get_drvdata(pdev); + /* + * 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(). + * + */ + if (pwm_is_enabled(pc->chip.pwms)) + clk_disable(pc->clk); + clk_unprepare(pc->clk); return pwmchip_remove(&pc->chip); -- 2.7.4