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pwm: rockchip: Avoid glitches on already running PWMs

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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>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Boris Brezillon 2016-06-14 11:13:13 +02:00 • committed by Thierry Reding
parent 1ebb74cf35
commit 48cf973cae
1 changed files with 19 additions and 1 deletions
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20
drivers/pwm/pwm-rockchip.c
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@ -319,7 +319,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
if (IS_ERR(pc->clk)) if (IS_ERR(pc->clk))
return PTR_ERR(pc->clk); return PTR_ERR(pc->clk);
ret = clk_prepare(pc->clk); ret = clk_prepare_enable(pc->clk);
if (ret) if (ret)
return 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); 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; return ret;
} }
@ -349,6 +353,20 @@ static int rockchip_pwm_remove(struct platform_device *pdev)
{ {
struct rockchip_pwm_chip *pc = platform_get_drvdata(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); clk_unprepare(pc->clk);
return pwmchip_remove(&pc->chip); return pwmchip_remove(&pc->chip);