Re: [PATCH 1/4] arm64: dts: qcom: sdm845: fix number of pins in 'gpio-ranges'

[Shawn Guo <shawn.guo@linaro.org>]

On Fri, Mar 05, 2021 at 07:56:02PM -0600, Bjorn Andersson wrote:
> On Fri 05 Mar 19:28 CST 2021, Shawn Guo wrote:
> 
> > On Fri, Mar 05, 2021 at 03:43:08PM -0600, Bjorn Andersson wrote:
> > > On Tue 02 Mar 21:31 CST 2021, Shawn Guo wrote:
> > > 
> > > > The last cell of 'gpio-ranges' should be number of GPIO pins, and in
> > > > case of qcom platform it should match msm_pinctrl_soc_data.ngpio rather
> > > > than msm_pinctrl_soc_data.ngpio - 1.
> > > > 
> > > 
> > > This is a historical artifact, SDM845 has 150 GPIO pins. In addition to
> > > this there's an output-only pin for UFS, which I exposed as an GPIO as
> > > well - but it's only supposed to be used as a reset-gpio for the UFS
> > > device.
> > > 
> > > Perhaps that still mandates that gpio-ranges should cover it?
> > 
> > I think the number in DT gpio-ranges should match msm_pinctrl_soc_data.ngpio.
> > Otherwise, kernel will be confused and be running into the issue like
> > below in some case.
> > 
> > > 
> > > > This fixes the problem that when the last GPIO pin in the range is
> > > > configured with the following call sequence, it always fails with
> > > > -EPROBE_DEFER.
> > > > 
> > > >     pinctrl_gpio_set_config()
> > > >         pinctrl_get_device_gpio_range()
> > > >             pinctrl_match_gpio_range()
> > > 
> > > When do we hit this sequence? I didn't think operations on the UFS
> > > GP(I)O would ever take this code path?
> > 
> > It will, if we have UFS driver booting from ACPI and requesting reset
> > GPIO.
> 
> But does the UFS driver somehow request GPIO 190 on SC8180x?
> 
> I made up the idea that this is a GPIO, there really only is 190 (0-189)
> GPIOs on thie SoC.
> 
> Downstream they use a pinconf node with "output-high"/"output-low" to
> toggle the reset pin and I don't find any references in the Flex 5G
> DSDT.

Right now, I do not have to request and configure this UFS GPIO for
getting UFS work with ACPI kernel.  And the immediate problem we have is
that with gpio_chip .set_config patch, devm_gpiod_get_optional() call
from UFS driver always gets -EPROBE_DEFER.

> 
> > And we are hit this sequence with my patch that adds .set_config
> > for gpio_chip [1].
> > 
> 
> What's calling pinctrl_gpio_set_config() in this case?

  ufs_qcom_probe
    ufshcd_pltfrm_init
      ufshcd_init
        ufs_qcom_init
          devm_gpiod_get_optional
            devm_gpiod_get_index
              gpiod_get_index
                gpiod_configure_flags
                  gpiod_direction_output
                    gpiochip_generic_config

Shawn