On Wed, Sep 06, 2023 at 04:41:33PM +0200, Robert Marko wrote:
> On Fri, Sep 1, 2023 at 1:49 PM Robert Marko <robert.marko@xxxxxxxxxx> wrote:
> >
> > Ever since PXA I2C driver was moved to the generic I2C recovery, I2C has
> > stopped working completely on Armada 3720 if the pins are specified in DTS.
> >
> > After a while it was traced down to the only difference being that PXA
> > driver did not change the pinmux state to GPIO before trying to acquire the
> > GPIO pins.
> > And indeed as soon as this call is removed I2C starts working.
> >
> > To me it seems that this call is not required at all as devm_gpiod_get()
> > will result in the pinmux state being changed to GPIO via the pinmux
> > set_mux() op.
> >
> > Fixes: 0b01392c18b9 ("i2c: pxa: move to generic GPIO recovery")
> > Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
> > ---
> > I am aware this probably isnt the correct fix, so I am sending it as RFC
> > cause I have ran out of ideas.
>
> CC-ing Russel as well since I forgot him.
So the generic recovery decided to set the pinmux state before calling
devm_gpiod_get(), where as the driver (and my code) originally did this
after calling devm_gpiod_get():
- /*
- * Claiming GPIOs can change the pinmux state, which confuses the
- * pinctrl since pinctrl's idea of the current setting is unaffected
- * by the pinmux change caused by claiming the GPIO. Work around that
- * by switching pinctrl to the GPIO state here. We do it this way to
- * avoid glitching the I2C bus.
- */
- pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery);
-
- return pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default);
I'd suggest re-implementing my original scheme in the generic code
because this _does_ work on Armada 3720 hardware.
Removing the pinmux frobbing is likely to break stuff.
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