linux-kernel - [PATCH v2 3/3] phy: amlogic: meson8b-usb2: fix shared reset control use

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Date:   Tue,  1 Dec 2020 20:01:00 +0100
From:   Amjad Ouled-Ameur <aouledameur@...libre.com>
To:     Kevin Hilman <khilman@...libre.com>
Cc:     Amjad Ouled-Ameur <aouledameur@...libre.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Felipe Balbi <balbi@...nel.org>,
        Jerome Brunet <jbrunet@...libre.com>,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: [PATCH v2 3/3] phy: amlogic: meson8b-usb2: fix shared reset control use

Use reset_control_rearm() call if an error occurs in case
phy_meson8b_usb2_power_on() fails after reset() has been called, or in
case phy_meson8b_usb2_power_off() is called i.e the resource is no longer
used and the reset line may be triggered again by other devices.

reset_control_rearm() keeps use of triggered_count sane in the reset
framework, use of reset_control_reset() on shared reset line should
be balanced with reset_control_rearm().

Signed-off-by: Amjad Ouled-Ameur <aouledameur@...libre.com>
Reported-by: Jerome Brunet <jbrunet@...libre.com>
---
changes since v1: [1]
* Moved reset_control_rearm after clk_disable_unprepare to clean things up
in reverse order of initialization for phy: amlogic: meson drivers

IMPORTANT:
This patchset depends on this patch [2], it adds reset_control_rearm() call
to the reset framework API, it has been approved by the maintainer, and
will be applied to reset/next

There is currently an immutable branch with it [3]

[1]: https://lore.kernel.org/lkml/20201113000508.14702-1-aouledameur@baylibre.com/
[2]: https://lore.kernel.org/lkml/20201112230043.28987-1-aouledameur@baylibre.com/
[3]: git://git.pengutronix.de/git/pza/linux.git reset/shared-retrigger

 drivers/phy/amlogic/phy-meson8b-usb2.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/phy/amlogic/phy-meson8b-usb2.c b/drivers/phy/amlogic/phy-meson8b-usb2.c
index 03c061dd5f0d..651eec41a896 100644
--- a/drivers/phy/amlogic/phy-meson8b-usb2.c
+++ b/drivers/phy/amlogic/phy-meson8b-usb2.c
@@ -154,6 +154,7 @@ static int phy_meson8b_usb2_power_on(struct phy *phy)
 	ret = clk_prepare_enable(priv->clk_usb_general);
 	if (ret) {
 		dev_err(&phy->dev, "Failed to enable USB general clock\n");
+		reset_control_rearm(priv->reset);
 		return ret;
 	}
 
@@ -161,6 +162,7 @@ static int phy_meson8b_usb2_power_on(struct phy *phy)
 	if (ret) {
 		dev_err(&phy->dev, "Failed to enable USB DDR clock\n");
 		clk_disable_unprepare(priv->clk_usb_general);
+		reset_control_rearm(priv->reset);
 		return ret;
 	}
 
@@ -199,6 +201,7 @@ static int phy_meson8b_usb2_power_on(struct phy *phy)
 				dev_warn(&phy->dev, "USB ID detect failed!\n");
 				clk_disable_unprepare(priv->clk_usb);
 				clk_disable_unprepare(priv->clk_usb_general);
+				reset_control_rearm(priv->reset);
 				return -EINVAL;
 			}
 		}
@@ -218,6 +221,7 @@ static int phy_meson8b_usb2_power_off(struct phy *phy)
 
 	clk_disable_unprepare(priv->clk_usb);
 	clk_disable_unprepare(priv->clk_usb_general);
+	reset_control_rearm(priv->reset);
 
 	return 0;
 }
-- 
2.17.1