[PATCH v5] net: phy: mdio-gpio: Fix working over slow can_sleep GPIOs

From: Martin Schiller
Date: Thu Nov 15 2018 - 00:24:54 EST


Up until commit 7e5fbd1e0700 ("net: mdio-gpio: Convert to use gpiod
functions where possible"), the _cansleep variants of the gpio_ API was
used. After that commit and the change to gpiod_ API, the _cansleep()
was dropped. This then results in WARN_ON() when used with GPIO
devices which do sleep. Add back the _cansleep() to avoid this.

Fixes: 7e5fbd1e0700 ("net: mdio-gpio: Convert to use gpiod functions where possible")
Signed-off-by: Martin Schiller <ms@xxxxxxxxxx>
---
v5:
- reworked commit message
- added "Fixes:" tag
- based on DaveM net tree instead of mainline

v4:
- remove linewrap of kernel message

v3:
- modified commit summary
- fixed commit cites in commit message
- fixed line continuation

v2:
- fixed copy/paste bug in warning about slow GPIO pins
---
drivers/net/phy/mdio-gpio.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
index 33265747bf39..3a5a24daf384 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 +162,10 @@ 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