UPSTREAM: pwm: rockchip: Avoid glitches on already running PWMs

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 48cf973cae33488f84d7ab79a0f613383cff4de4)

Conflicts:
	drivers/pwm/pwm-rockchip.c

Change-Id: I75ffccd19c5244568fc0034d1585dac490296111
Signed-off-by: David Wu <david.wu@rock-chips.com>

diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index dc785f0236713678c3a1c93627f1a1e804275045..52592643f3a6ee1d290ea02cdb983252372225e5 100644 (file)
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -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);