[PATCH v3] soc: imx: gpcv2: Assert reset before ungating clock

[Marek Vasut]

In case the power domain clock are ungated before the reset is asserted,
the system might freeze completely. This is likely due to a device is an
undefined state being attached to bus, which sporadically leads to a bus
hang. Assert the reset before the clock are enabled to assure the device
is in defined state before being attached to bus.

Fixes: fe58c887fb8ca ("soc: imx: gpcv2: add support for optional resets")
Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Fabio Estevam <festevam at denx.de>
Cc: Frieder Schrempf <frieder.schrempf at kontron.de>
Cc: Lucas Stach <l.stach at pengutronix.de>
Cc: NXP Linux Team <linux-imx at nxp.com>
Cc: Peng Fan <peng.fan at nxp.com>
Cc: Shawn Guo <shawnguo at kernel.org>
To: linux-arm-kernel at lists.infradead.org
---
V2: - Always assert the reset before enabling clock
    - Update commit message
    - Add Fixes tag
V3: Move the extra delay past clk_prepare_enable()
---
 drivers/soc/imx/gpcv2.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
index 6383a4edc3607..88aee59730e39 100644
--- a/drivers/soc/imx/gpcv2.c
+++ b/drivers/soc/imx/gpcv2.c
@@ -335,6 +335,8 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
 		}
 	}
 
+	reset_control_assert(domain->reset);
+
 	/* Enable reset clocks for all devices in the domain */
 	ret = clk_bulk_prepare_enable(domain->num_clks, domain->clks);
 	if (ret) {
@@ -342,7 +344,8 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
 		goto out_regulator_disable;
 	}
 
-	reset_control_assert(domain->reset);
+	/* delays for reset to propagate */
+	udelay(5);
 
 	if (domain->bits.pxx) {
 		/* request the domain to power up */
-- 
2.35.1