Re: [QUESTION] i2c: designware: Why use GPIOD_OUT_HIGH instead of OPEN_DRAIN for recovery?

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, Jan 12, 2026 at 10:10:02PM +0800, Alex Ivy wrote:

> I am currently looking at the bus recovery implementation in
> drivers/i2c/busses/i2c-designware-master.c. I noticed that
> i2c_dw_init_recovery_info() seems to manually reimplement much of the logic
> already present in the I2C core's i2c_gpio_init_generic_recovery().
> 
> However, there are two key differences that caught my attention:
> 
> GPIO Flags: The I2C core uses GPIOD_OUT_HIGH_OPEN_DRAIN, while
> i2c-designware uses GPIOD_OUT_HIGH. Is this specifically intended to
> support SoC GPIO controllers that do not implement the OPEN_DRAIN flag,
> which would otherwise cause devm_gpiod_get() to fail in the core's generic
> helper?
> 
> Initialization Flow: The core's helper performs a pinctrl state toggle
> (GPIO -> Default) during initialization, whereas i2c-designware only looks
> up the states and defers the actual switching to prepare_recovery.

This might affect the workflow. Note, in the past one of such conversion was
presumably done without real testing and brought a regression (I'm talking
about PXA version).

> My question is: Would it be possible (or welcomed) to refactor this to use
> the core's generic helper, or is the current manual initialization required
> to maintain compatibility with specific DesignWare-integrated SoCs (like
> certain Intel or ARM platforms) that have restrictive GPIO/Pinctrl
> requirements?
> 
> I would appreciate your insights on the historical background of these
> choices.

Do you have an access to real HW?

-- 
With Best Regards,
Andy Shevchenko