pwm: mtk-disp: Fix the parameters calculated by the enabled flag of disp_pwm

In the original mtk_disp_pwm_get_state() function wrongly uses bit 0 of
CON0 to judge if the PWM is enabled.
However that is indicated by a bit (at a machine dependent position) in
the DISP_PWM_EN register. Fix this accordingly.

Fixes: 3f2b1673 ("pwm: mtk-disp: Implement atomic API .get_state()")
Signed-off-by: xinlei lee <xinlei.lee@mediatek.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/1666172538-11652-1-git-send-email-xinlei.lee@mediatek.comSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-mtk-disp.c

@@ -178,7 +178,7 @@ static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
 {
 	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
 	u64 rate, period, high_width;
-	u32 clk_div, con0, con1;
+	u32 clk_div, pwm_en, con0, con1;
 	int err;
 
 	err = clk_prepare_enable(mdp->clk_main);
@@ -197,7 +197,8 @@ static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
 	rate = clk_get_rate(mdp->clk_main);
 	con0 = readl(mdp->base + mdp->data->con0);
 	con1 = readl(mdp->base + mdp->data->con1);
-	state->enabled = !!(con0 & BIT(0));
+	pwm_en = readl(mdp->base + DISP_PWM_EN);
+	state->enabled = !!(pwm_en & mdp->data->enable_mask);
 	clk_div = FIELD_GET(PWM_CLKDIV_MASK, con0);
 	period = FIELD_GET(PWM_PERIOD_MASK, con1);
 	/*