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

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Date:   Tue, 13 Sep 2022 16:04:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marek Vasut <marex@...x.de>,
        Fabio Estevam <festevam@...x.de>,
        Lucas Stach <l.stach@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 053/121] soc: imx: gpcv2: Assert reset before ungating clock

From: Marek Vasut <marex@...x.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@...x.de>
Reviewed-by: Fabio Estevam <festevam@...x.de>
Reviewed-by: Lucas Stach <l.stach@...gutronix.de>
Signed-off-by: Shawn Guo <shawnguo@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.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