[PATCH v3 5/6] pwm: mediatek: add PWM_CLK_DIV_MAX

[Zhi Mao]

1. Replace "7" with "PWM_CLK_DIV_MAX" in function:mtk_pwm_config()
to improve the code readablity.
2. add pwm clk disable in function:mtk_pwm_config()
for error parameter checking case.

Signed-off-by: Zhi Mao <zhi....@mediatek.com>
---
 drivers/pwm/pwm-mediatek.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index 554a042..1d78ab1 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -30,6 +30,8 @@
 #define PWMDWIDTH              0x2c
 #define PWMTHRES               0x30
 
+#define PWM_CLK_DIV_MAX                7
+
 enum {
        MTK_CLK_MAIN = 0,
        MTK_CLK_TOP,
@@ -130,8 +132,11 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct 
pwm_device *pwm,
                clkdiv++;
        }
 
-       if (clkdiv > 7)
+       if (clkdiv > PWM_CLK_DIV_MAX) {
+               mtk_pwm_clk_disable(chip, pwm);
+               dev_err(chip->dev, "period %d not supported\n", period_ns);
                return -EINVAL;
+       }
 
        mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
        mtk_pwm_writel(pc, pwm->hwpwm, PWMDWIDTH, period_ns / resolution);
-- 
1.7.9.5