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Subject[PATCH 09/15 v4] gpio: devres: Handle nonexclusive GPIOs
Date
When we get a nonexeclusive GPIO descriptor using managed
resources, we should only add it to the list of managed
resources once: on the first user. Augment the
devm_gpiod_get_index() and devm_gpiod_get_from_of_node()
calls to account for this by checking if the descriptor
is already resource managed before we proceed to allocate
a new resource management struct.

Cc: Mark Brown <broonie@kernel.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: b0ce7b29bfcd ("regulator/gpio: Allow nonexclusive GPIO access")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v3->v4:
- Pass a pointer to a pointer &desc instead of just the
descriptor pointer: it is the memory address storing the
pointer that hooks into resource management.
ChangeLog v1->v3:
- New patch.
- This fix is in response to an issue Marek saw in the fixups
for resource-managed GPIO descriptors used with ena_gpiod
in the regulator subsystem.
- I first thought to apply it to the GPIO tree directly, but
since it is not a regression it is better to put it into
the regulator tree with the rest of the patches.
---
drivers/gpio/gpiolib-devres.c | 50 ++++++++++++++++++++++++++---------
1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
index 01959369360b..f9591b5c9748 100644
--- a/drivers/gpio/gpiolib-devres.c
+++ b/drivers/gpio/gpiolib-devres.c
@@ -98,15 +98,28 @@ struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
struct gpio_desc **dr;
struct gpio_desc *desc;

+ desc = gpiod_get_index(dev, con_id, idx, flags);
+ if (IS_ERR(desc))
+ return desc;
+
+ /*
+ * For non-exclusive GPIO descriptors, check if this descriptor is
+ * already under resource management by this device.
+ */
+ if (flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
+ struct devres *dres;
+
+ dres = devres_find(dev, devm_gpiod_release,
+ devm_gpiod_match, &desc);
+ if (dres)
+ return desc;
+ }
+
dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
GFP_KERNEL);
- if (!dr)
+ if (!dr) {
+ gpiod_put(desc);
return ERR_PTR(-ENOMEM);
-
- desc = gpiod_get_index(dev, con_id, idx, flags);
- if (IS_ERR(desc)) {
- devres_free(dr);
- return desc;
}

*dr = desc;
@@ -140,15 +153,28 @@ struct gpio_desc *devm_gpiod_get_from_of_node(struct device *dev,
struct gpio_desc **dr;
struct gpio_desc *desc;

+ desc = gpiod_get_from_of_node(node, propname, index, dflags, label);
+ if (IS_ERR(desc))
+ return desc;
+
+ /*
+ * For non-exclusive GPIO descriptors, check if this descriptor is
+ * already under resource management by this device.
+ */
+ if (dflags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
+ struct devres *dres;
+
+ dres = devres_find(dev, devm_gpiod_release,
+ devm_gpiod_match, &desc);
+ if (dres)
+ return desc;
+ }
+
dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
GFP_KERNEL);
- if (!dr)
+ if (!dr) {
+ gpiod_put(desc);
return ERR_PTR(-ENOMEM);
-
- desc = gpiod_get_from_of_node(node, propname, index, dflags, label);
- if (IS_ERR(desc)) {
- devres_free(dr);
- return desc;
}

*dr = desc;
--
2.19.2
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