soc: mediatek: pm-domains: Fix the power glitch issue

Power reset maybe generate unexpected signal. In order to avoid
the glitch issue, we need to enable isolation first to guarantee the
stable signal when power reset is triggered.

Fixes: 59b644b ("soc: mediatek: Add MediaTek SCPSYS power domains")
Signed-off-by: Chun-Jie Chen <[email protected]>
Signed-off-by: Allen-KH Cheng <[email protected]>
Reviewed-by: Chen-Yu Tsai <[email protected]>
Reviewed-by: Miles Chen <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Matthias Brugger <[email protected]>

Author: Chun-Jie Chen

drivers/soc/mediatek/mtk-pm-domains.c

@@ -275,9 +275,9 @@ static int scpsys_power_off(struct generic_pm_domain *genpd)
 	clk_bulk_disable_unprepare(pd->num_subsys_clks, pd->subsys_clks);
 
 	/* subsys power off */
-	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
 	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_ISO_BIT);
 	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_CLK_DIS_BIT);
+	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
 	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ON_2ND_BIT);
 	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ON_BIT);