Re: [PATCH 2/2] pinctrl: qcom: spmi-gpio: make direction changes exclusive

[Shawn Guo]

On Tue, Sep 15, 2026 at 03:11:48PM +0200, Neil Armstrong wrote:
> On 9/15/26 03:44, Shawn Guo wrote:
> > pmic_gpio_populate() seeds pad->input_enabled and pad->output_enabled from
> > the hardware MODE_CTL register, so a pad left in DIGITAL_INPUT or
> > DIGITAL_INPUT_OUTPUT mode by the bootloader starts out with the input
> > buffer enabled.  Neither direction callback clears the opposite buffer:
> > .direction_output() only packs PIN_CONFIG_LEVEL, which sets
> > output_enabled, and .direction_input() only packs PIN_CONFIG_INPUT_ENABLE,
> > which sets input_enabled.  Requesting either direction on such a pad
> > therefore programs MODE_DIGITAL_INPUT_OUTPUT rather than the requested
> > direction.
> > 
> > That silently breaks both directions.  After gpiod_direction_input() the
> > pad keeps driving the line, since the output buffer is never disabled.
> > And after gpiod_direction_output() pmic_gpio_get_direction() still reports
> > GPIO_LINE_DIRECTION_IN, because it cannot tell plain input from
> > input+output, which makes gpiolib consider the line an input while the
> > driver is driving it.  On a board where several regulator-fixed nodes
> > share one PMIC GPIO the shared GPIO proxy reads that direction back and
> > rejects every consumer after the first:
> > 
> >    reg-fixed-voltage regulator-wcn-core-vm-1p35: setup of GPIO (default) failed: -1
> >    reg-fixed-voltage regulator-wcn-core-vm-1p35: error -EPERM: can't get GPIO
> > 
> > Pack the opposite buffer's PIN_CONFIG_*_ENABLE along with the requested
> > direction so that the resulting MODE_CTL is DIGITAL_INPUT or
> > DIGITAL_OUTPUT, never both.  pmic_gpio_config_set() programs the registers
> > once after walking all configs, so this stays a single register write.
> > 
> > Pads that are genuinely bidirectional can still be described that way
> > through pinconf, which is the interface that has always been able to
> > express it; the gpiolib direction callbacks now mean what gpiolib says
> > they mean.
> > 
> > Assisted-by: LLM
> > Fixes: eadff3024472 ("pinctrl: Qualcomm SPMI PMIC GPIO pin controller driver")
> 
> You should add:
> Fixes: 263447532463 ("pinctrl: qcom: spmi-gpio: implement .get_direction()")
> 
> Since my change added the get_direction callback.

Indeed!

> 
> Personally I would prefer patch 1 instead of this change.

As I mentioned in the cover letter, both patches are fixing real bugs
existing at different level. So I prefer to merge both. But it's a call
up to Bartosz.

Shawn