path: root/arch/blackfin/mach-bf533
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authorLinus Walleij <>2017-09-10 19:54:21 +0200
committerLinus Walleij <>2017-10-30 08:42:37 +0100
commit7bb75029ef34838604357350b4f24d6535e9d01f (patch)
tree308c8bd845eacf62c4fbc29b03783cd569f83fdd /arch/blackfin/mach-bf533
parentf926dfc112bc6cf41d7068ee5e3f261e13a5bec8 (diff)
i2c: gpio: Enforce open drain through gpiolib
The I2C GPIO bitbang driver currently emulates open drain behaviour by implementing what the gpiolib already does: not actively driving the line high, instead setting it to input. This makes no sense. Use the new facility in gpiolib to request the lines enforced into open drain mode, and let the open drain emulation already present in the gpiolib kick in and handle this. As a bonus: if the GPIO driver in the back-end actually supports open drain in hardware using the .set_config() callback, it will be utilized. That's correct: we never used that hardware feature before, instead relying on emulating open drain even if the GPIO controller could actually handle this for us. Users will sometimes get messages like this: gpio-485 (?): enforced open drain please flag it properly in DT/ACPI DSDT/board file gpio-486 (?): enforced open drain please flag it properly in DT/ACPI DSDT/board file i2c-gpio gpio-i2c: using lines 485 (SDA) and 486 (SCL) Which is completely proper: since the line is used as open drain, it should actually be flagged properly with e.g. gpios = <&gpio0 5 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>, <&gpio0 6 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>; Or similar facilities in board file descriptor tables or ACPI DSDT. Tested-by: Geert Uytterhoeven <> Signed-off-by: Linus Walleij <>
Diffstat (limited to 'arch/blackfin/mach-bf533')
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