linux-kernel - [PATCH v2] net: phy: mdio-gpio: fix access that may sleep

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Message-Id: <20181114063703.13379-1-ms@dev.tdt.de>
Date:   Wed, 14 Nov 2018 07:37:03 +0100
From:   Martin Schiller <ms@....tdt.de>
To:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     andrew@...n.ch, f.fainelli@...il.com, davem@...emloft.net,
        Martin Schiller <ms@....tdt.de>
Subject: [PATCH v2] net: phy: mdio-gpio: fix access that may sleep

This commit re-enables support for slow GPIO pins. It was initially
introduced by commit
	2d6c9091ab7630dfcf34417c6683ce4764d7d40a
and got lost by commit
	7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12

Also add a warning about slow GPIO pins like it is done in i2c-gpio.

Signed-off-by: Martin Schiller <ms@....tdt.de>
---
v2:
 - fixed copy/paste bug in warning about slow GPIO pins
---
 drivers/net/phy/mdio-gpio.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
index 33265747bf39..6c1cca14689b 100644
--- a/drivers/net/phy/mdio-gpio.c
+++ b/drivers/net/phy/mdio-gpio.c
@@ -63,7 +63,7 @@ static void mdio_dir(struct mdiobb_ctrl *ctrl, int dir)
 		 * assume the pin serves as pull-up. If direction is
 		 * output, the default value is high.
 		 */
-		gpiod_set_value(bitbang->mdo, 1);
+		gpiod_set_value_cansleep(bitbang->mdo, 1);
 		return;
 	}
 
@@ -78,7 +78,7 @@ static int mdio_get(struct mdiobb_ctrl *ctrl)
 	struct mdio_gpio_info *bitbang =
 		container_of(ctrl, struct mdio_gpio_info, ctrl);
 
-	return gpiod_get_value(bitbang->mdio);
+	return gpiod_get_value_cansleep(bitbang->mdio);
 }
 
 static void mdio_set(struct mdiobb_ctrl *ctrl, int what)
@@ -87,9 +87,9 @@ static void mdio_set(struct mdiobb_ctrl *ctrl, int what)
 		container_of(ctrl, struct mdio_gpio_info, ctrl);
 
 	if (bitbang->mdo)
-		gpiod_set_value(bitbang->mdo, what);
+		gpiod_set_value_cansleep(bitbang->mdo, what);
 	else
-		gpiod_set_value(bitbang->mdio, what);
+		gpiod_set_value_cansleep(bitbang->mdio, what);
 }
 
 static void mdc_set(struct mdiobb_ctrl *ctrl, int what)
@@ -97,7 +97,7 @@ static void mdc_set(struct mdiobb_ctrl *ctrl, int what)
 	struct mdio_gpio_info *bitbang =
 		container_of(ctrl, struct mdio_gpio_info, ctrl);
 
-	gpiod_set_value(bitbang->mdc, what);
+	gpiod_set_value_cansleep(bitbang->mdc, what);
 }
 
 static const struct mdiobb_ops mdio_gpio_ops = {
@@ -162,6 +162,11 @@ static int mdio_gpio_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	if (gpiod_cansleep(bitbang->mdc) || gpiod_cansleep(bitbang->mdio)
+		|| gpiod_cansleep(bitbang->mdo))
+		dev_warn(&pdev->dev, "Slow GPIO pins might wreak havoc into"
+				     "MDIO bus timing");
+
 	if (pdev->dev.of_node) {
 		bus_id = of_alias_get_id(pdev->dev.of_node, "mdio-gpio");
 		if (bus_id < 0) {
-- 
2.11.0