[PATCH] pwm: rockchip: State of pwm clock should synchronize with pwm enabled state

David Wu
2017-02-28T06:43:36Z

From: "david.wu" <david.wu@rock-chips.com>

If the pwm was not enabled at uboot 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 uboot 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/disable, and
pwm driver ensure state of pwm clock synchronized with pwm enabled state.

Signed-off-by: David Wu <david.wu@rock-chips.com>
---
drivers/pwm/pwm-rockchip.c | 38 +++++++++++++++++++++++++++++++-------
1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index ef89df1..14a0445 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -191,6 +191,26 @@ static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
return 0;
}

+static int rk_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 +227,26 @@ 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 = rk_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);
-
+ rk_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 = rk_pwm_enable(chip, pwm, state->enabled,
+ state->polarity);
+ if (ret)
+ goto out;
+ }

/*
* Update the state with the real hardware, which can differ a bit
--
1.9.1