pwm: rockchip: State of PWM clock should synchronize with PWM enabled state

If the PWM was not enabled at U-Boot loader, PWM could not work for
clock always disabled at PWM driver. The PWM clock is enabled at
beginning of pwm_apply(), but disabled at end of pwm_apply().

If the PWM was enabled at U-Boot loader, PWM clock is always enabled
unless closed by ATF. The pwm-backlight might turn off the power at
early suspend, should disable PWM clock for saving power consume.

It is important to provide opportunity to enable/disable clock at PWM
driver, the PWM consumer should ensure correct order to call PWM enable
and disable, and PWM driver ensure state of PWM clock synchronized with
PWM enabled state.

Fixes: 2bf1c98aa5a4 ("pwm: rockchip: Add support for atomic update")
Cc: stable@vger.kernel.org
Signed-off-by: David Wu <david.wu@rock-chips.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index ef89df1f7336c77a70c3a4de42b6d71ec96162ba..744d56197286a45eb148de437d31a3c3ca8fbd1a 100644 (file)
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -191,6 +191,28 @@ static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
        return 0;
 }
 
+static int rockchip_pwm_enable(struct pwm_chip *chip,
+                        struct pwm_device *pwm,
+                        bool enable,
+                        enum pwm_polarity polarity)
+{
+       struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
+       int ret;
+
+       if (enable) {
+               ret = clk_enable(pc->clk);
+               if (ret)
+                       return ret;
+       }
+
+       pc->data->set_enable(chip, pwm, enable, polarity);
+
+       if (!enable)
+               clk_disable(pc->clk);
+
+       return 0;
+}
+
 static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
                              struct pwm_state *state)
 {
@@ -207,22 +229,26 @@ static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
                return ret;
 
        if (state->polarity != curstate.polarity && enabled) {
-               pc->data->set_enable(chip, pwm, false, state->polarity);
+               ret = rockchip_pwm_enable(chip, pwm, false, state->polarity);
+               if (ret)
+                       goto out;
                enabled = false;
        }
 
        ret = rockchip_pwm_config(chip, pwm, state->duty_cycle, state->period);
        if (ret) {
                if (enabled != curstate.enabled)
-                       pc->data->set_enable(chip, pwm, !enabled,
-                                            state->polarity);
-
+                       rockchip_pwm_enable(chip, pwm, !enabled,
+                                     state->polarity);
                goto out;
        }
 
-       if (state->enabled != enabled)
-               pc->data->set_enable(chip, pwm, state->enabled,
-                                    state->polarity);
+       if (state->enabled != enabled) {
+               ret = rockchip_pwm_enable(chip, pwm, state->enabled,
+                                   state->polarity);
+               if (ret)
+                       goto out;
+       }
 
        /*
         * Update the state with the real hardware, which can differ a bit