[PATCH 5.15 053/121] soc: imx: gpcv2: Assert reset before ungating clock

Greg Kroah-Hartman
2022-09-13T14:31:47Z

From: Marek Vasut <marex@denx.de>

[ Upstream commit df88005bd81b80c944d185554e264a4b0f993c37 ]

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@denx.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 b4aa28420f2a8..4dc3a3f73511e 100644
--- a/drivers/soc/imx/gpcv2.c
+++ b/drivers/soc/imx/gpcv2.c
@@ -237,6 +237,8 @@ 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) {
@@ -244,7 +246,8 @@ 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