soc: imx: gpc: fix power up sequencing

Currently we wait only until the PGC inverts the isolation setting
before disabling the peripheral clocks. This doesn't ensure that the
reset is properly propagated through the peripheral devices in the
power domain.

Wait until the PGC signals that the power up request is done and
wait a bit for resets to propagate before disabling the clocks.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/soc/imx/gpc.c

@@ -87,8 +87,8 @@ static int imx6_pm_domain_power_off(struct generic_pm_domain *genpd)
 static int imx6_pm_domain_power_on(struct generic_pm_domain *genpd)
 {
 	struct imx_pm_domain *pd = to_imx_pm_domain(genpd);
-	int i, ret, sw, sw2iso;
-	u32 val;
+	int i, ret;
+	u32 val, req;
 
 	if (pd->supply) {
 		ret = regulator_enable(pd->supply);
@@ -107,17 +107,18 @@ static int imx6_pm_domain_power_on(struct generic_pm_domain *genpd)
 	regmap_update_bits(pd->regmap, pd->reg_offs + GPC_PGC_CTRL_OFFS,
 			   0x1, 0x1);
 
-	/* Read ISO and ISO2SW power up delays */
-	regmap_read(pd->regmap, pd->reg_offs + GPC_PGC_PUPSCR_OFFS, &val);
-	sw = val & 0x3f;
-	sw2iso = (val >> 8) & 0x3f;
-
 	/* Request GPC to power up domain */
-	val = BIT(pd->cntr_pdn_bit + 1);
-	regmap_update_bits(pd->regmap, GPC_CNTR, val, val);
+	req = BIT(pd->cntr_pdn_bit + 1);
+	regmap_update_bits(pd->regmap, GPC_CNTR, req, req);
 
-	/* Wait ISO + ISO2SW IPG clock cycles */
-	udelay(DIV_ROUND_UP(sw + sw2iso, pd->ipg_rate_mhz));
+	/* Wait for the PGC to handle the request */
+	ret = regmap_read_poll_timeout(pd->regmap, GPC_CNTR, val, !(val & req),
+				       1, 50);
+	if (ret)
+		pr_err("powerup request on domain %s timed out\n", genpd->name);
+
+	/* Wait for reset to propagate through peripherals */
+	usleep_range(5, 10);
 
 	/* Disable reset clocks for all devices in the domain */
 	for (i = 0; i < pd->num_clks; i++)
@@ -343,6 +344,7 @@ static const struct regmap_config imx_gpc_regmap_config = {
 	.rd_table = &access_table,
 	.wr_table = &access_table,
 	.max_register = 0x2ac,
+	.fast_io = true,
 };
 
 static struct generic_pm_domain *imx_gpc_onecell_domains[] = {