On úterý 9. ledna 2018 19:08:21 CET, Geert Uytterhoeven wrote:
Since commit f11a04464ae57e8d ("i2c: gpio: Enable working over slow
can_sleep GPIOs"), probing the i2c RTC connected to an i2c-gpio bus on
r8a7740/armadillo fails with:
rtc-s35390a 0-0030: error resetting chip
rtc-s35390a: probe of 0-0030 failed with error -5
More debug code reveals:
i2c i2c-0: master_xfer[0] R, addr=0x30, len=1
i2c i2c-0: NAK from device addr 0x30 msg #0
s35390a_get_reg: ret = -6
Commit 02e479808b5d62f8 ("gpio: Alter semantics of *raw* operations to
actually be raw") moved open drain/source handling from
gpiod_set_raw_value_commit() to gpiod_set_value(), but forgot to take
into account that gpiod_set_value_cansleep() also needs this handling.
The i2c protocol mandates that i2c signals are open drain, hence i2c
communication fails.
Fix this by adding the missing handling to gpiod_set_value_cansleep(),
using a new common helper __gpiod_set_value_nocheck().
Fixes: 02e479808b5d62f8 ("gpio: Alter semantics of *raw*
operations to actually be raw")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
The bad gpio commit is in v4.15-rc1 and later.
The i2c commit exposing this is not yet upstream, but in i2c/for-next.
---
drivers/gpio/gpiolib.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 358bce6e798b476c..7761d632a5b0dd20 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2927,6 +2927,18 @@ void gpiod_set_raw_value(struct
gpio_desc *desc, int value)
}
EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
+static void __gpiod_set_value_nocheck(struct gpio_desc *desc, int value)
+{
+ if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
+ value = !value;
+ if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
+ gpio_set_open_drain_value_commit(desc, value);
+ else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
+ gpio_set_open_source_value_commit(desc, value);
+ else
+ gpiod_set_raw_value_commit(desc, value);
+}
+
/**
* gpiod_set_value() - assign a gpio's value
* @desc: gpio whose value will be assigned
@@ -2941,16 +2953,8 @@ EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
void gpiod_set_value(struct gpio_desc *desc, int value)
{
VALIDATE_DESC_VOID(desc);
- /* Should be using gpiod_set_value_cansleep() */
WARN_ON(desc->gdev->chip->can_sleep);
- if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
- value = !value;
- if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
- gpio_set_open_drain_value_commit(desc, value);
- else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
- gpio_set_open_source_value_commit(desc, value);
- else
- gpiod_set_raw_value_commit(desc, value);
+ __gpiod_set_value_nocheck(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_value);
@@ -3277,9 +3281,7 @@ void gpiod_set_value_cansleep(struct
gpio_desc *desc, int value)
{
might_sleep_if(extra_checks);
VALIDATE_DESC_VOID(desc);
- if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
- value = !value;
- gpiod_set_raw_value_commit(desc, value);
+ __gpiod_set_value_nocheck(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep);
I realize that I'm late to the party (a merge request has been sent), but I
can confirm that I tested that this still works for a bitbang I2C over GPIO
pins connected to MAX14830 managed by max310x.
Tested-By: Jan Kundrát <jan.kundrat@xxxxxxxxx>
Cheers,
Jan
