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UPSTREAM: 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>
(commit 48cf973cae)

Conflicts:
	drivers/pwm/pwm-rockchip.c

Change-Id: I75ffccd19c5244568fc0034d1585dac490296111
Signed-off-by: David Wu <david.wu@rock-chips.com>
This commit is contained in:
Boris Brezillon
2016-06-14 11:13:13 +02:00
committed by Huang, Tao
parent c365d86972
commit 370a8d95d4
1 changed files with 24 additions and 2 deletions
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26
drivers/pwm/pwm-rockchip.c
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@@ -354,13 +354,13 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
return ret;
}
ret = clk_prepare(pc->clk);
ret = clk_prepare_enable(pc->clk);
if (ret) {
dev_err(&pdev->dev, "Can't prepare pwm clk: %d\n", ret);
return ret;
}
ret = clk_prepare(pc->pclk);
ret = clk_prepare_enable(pc->pclk);
if (ret) {
dev_err(&pdev->dev, "Can't prepare pclk: %d\n", ret);
goto err_clk;
@@ -386,6 +386,12 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
goto err_pclk;
}
/* Keep the PWM clk enabled if the PWM appears to be up and running. */
if (!pwm_is_enabled(pc->chip.pwms)) {
clk_disable(pc->pclk);
clk_disable(pc->clk);
}
return 0;
err_pclk:
@@ -400,6 +406,22 @@ 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->pclk);
clk_disable(pc->clk);
}
clk_unprepare(pc->pclk);
clk_unprepare(pc->clk);