This PWM Timer cannot output low because setting 0x000 is prohibited
on PWMCNT.PH0 (High-Level Period) bitfields. So, avoiding
the prohibited, this patch adds a workaround function to change
the value from 0 to 1 as pseudo low level.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
drivers/pwm/pwm-rcar.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index e479b6a..888cb37 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -166,6 +166,20 @@ static void rcar_pwm_disable(struct rcar_pwm_chip *rp)
rcar_pwm_update(rp, RCAR_PWMCR_EN0, 0, RCAR_PWMCR);
}
+static void rcar_pwm_workaround_output_low(struct rcar_pwm_chip *rp)
+{
+ /*
+ * This PWM Timer cannot output low because setting 0x000 is
+ * prohibited on PWMCNT.PH0 (High-Level Period) bitfields. So, avoiding
+ * the prohibited, this function changes the value from 0 to 1 as
+ * pseudo low level.
+ *
+ * TODO: Add GPIO handling to output low level.
+ */
+ if ((rp->pwmcnt & RCAR_PWMCNT_PH0_MASK) == 0)
+ rp->pwmcnt |= 1;
+}
+
static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
@@ -179,6 +193,7 @@ static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);
rcar_pwm_calc_counter(rp, div, state->duty_cycle, state->period);
+ rcar_pwm_workaround_output_low(rp);
ret = rcar_pwm_set_counter(rp);
if (!ret)
rcar_pwm_set_clock_control(rp, div);
--
1.9.1
