Subject: Re: [PATCH v3 1/3] thermal: rockchip: fix up the tsadc pinctrl setting error

From: Heiko Stuebner <[email-masked]>
Date: Wed, 22 May 2019 14:27:35 +0200

Hi Enric,

Am Montag, 20. Mai 2019, 15:38:32 CEST schrieb Enric Balletbo Serra:
> Hi all,
> 
> As pointed by [1] and [2] this commit, that now is upstream, breaks
> veyron (rk3288) and kevin (rk3399) boards. The problem is especially
> critical for veyron boards because they don't boot anymore.
> 
> I didn't look deep at the problem but I have some concerns about this
> patch, see below.
> 
> [1] https://www.spinics.net/lists/linux-rockchip/msg24657.html
> [2] https://www.spinics.net/lists/linux-rockchip/msg24735.html
> 
> Missatge de Daniel Lezcano <[email-masked]> del dia dt., 30
> d’abr. 2019 a les 15:39:
> >
> > On 30/04/2019 12:09, Elaine Zhang wrote:
> > > Explicitly use the pinctrl to set/unset the right mode
> > > instead of relying on the pinctrl init mode.
> > > And it requires setting the tshut polarity before select pinctrl.
> > >
> > > When the temperature sensor mode is set to 0, it will automatically
> > > reset the board via the Clock-Reset-Unit (CRU) if the over temperature
> > > threshold is reached. However, when the pinctrl initializes, it does a
> > > transition to "otp_out" which may lead the SoC restart all the time.
> > >
> > > "otp_out" IO may be connected to the RESET circuit on the hardware.
> > > If the IO is in the wrong state, it will trigger RESET.
> > > (similar to the effect of pressing the RESET button)
> > > which will cause the soc to restart all the time.
> > >
> > > Signed-off-by: Elaine Zhang <[email-masked]>
> >
> > Reviewed-by: Daniel Lezcano <[email-masked]>
> >
> >
> >
> > > ---
> > >  drivers/thermal/rockchip_thermal.c | 36 +++++++++++++++++++++++++++++++++---
> > >  1 file changed, 33 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
> > > index 9c7643d62ed7..6dc7fc516abf 100644
> > > --- a/drivers/thermal/rockchip_thermal.c
> > > +++ b/drivers/thermal/rockchip_thermal.c
> > > @@ -172,6 +172,9 @@ struct rockchip_thermal_data {
> > >       int tshut_temp;
> > >       enum tshut_mode tshut_mode;
> > >       enum tshut_polarity tshut_polarity;
> > > +     struct pinctrl *pinctrl;
> > > +     struct pinctrl_state *gpio_state;
> > > +     struct pinctrl_state *otp_state;
> > >  };
> > >
> > >  /**
> > > @@ -1242,6 +1245,8 @@ static int rockchip_thermal_probe(struct platform_device *pdev)
> > >               return error;
> > >       }
> > >
> > > +     thermal->chip->control(thermal->regs, false);
> > > +
> 
> That's the line that causes the hang. Commenting this makes the veyron
> boot again. Probably this needs to go after chip->initialize?

It needs to go after the clk_enable calls.
At this point the tsadc may still be unclocked.

> 
> > >       error = clk_prepare_enable(thermal->clk);
> > >       if (error) {
> > >               dev_err(&pdev->dev, "failed to enable converter clock: %d\n",
> > > @@ -1267,6 +1272,30 @@ static int rockchip_thermal_probe(struct platform_device *pdev)
> > >       thermal->chip->initialize(thermal->grf, thermal->regs,
> > >                                 thermal->tshut_polarity);
> > >
> > > +     if (thermal->tshut_mode == TSHUT_MODE_GPIO) {
> > > +             thermal->pinctrl = devm_pinctrl_get(&pdev->dev);
> > > +             if (IS_ERR(thermal->pinctrl)) {
> > > +                     dev_err(&pdev->dev, "failed to find thermal pinctrl\n");
> > > +                     return PTR_ERR(thermal->pinctrl);
> > > +             }
> > > +
> > > +             thermal->gpio_state = pinctrl_lookup_state(thermal->pinctrl,
> > > +                                                        "gpio");
> 
> Shouldn't this mode be documented properly in the binding first?

More importantly, it should be _backwards-compatible_, aka work with
old devicetrees without that property and not break thermal handling for
them entirely.

> 
> The binding [3] talks about init, default and sleep states but *not*
> gpio and otpout. The patch series looks incomplete to me or not using
> the proper names.
> 
> [3] https://elixir.bootlin.com/linux/v5.2-rc1/source/Documentation/devicetree/bindings/thermal/rockchip-thermal.txt
> 
> > > +             if (IS_ERR_OR_NULL(thermal->gpio_state)) {
> > > +                     dev_err(&pdev->dev, "failed to find thermal gpio state\n");
> > > +                     return -EINVAL;
> > > +             }
> > > +
> > > +             thermal->otp_state = pinctrl_lookup_state(thermal->pinctrl,
> > > +                                                       "otpout");
> > > +             if (IS_ERR_OR_NULL(thermal->otp_state)) {
> > > +                     dev_err(&pdev->dev, "failed to find thermal otpout state\n");
> > > +                     return -EINVAL;
> > > +             }
> > > +
> 
> Same here otpout is not a documented.
> 
> As this change is now in mainline and is causing veyron to hang I'd
> suggest reverting this change for now. Even fixing the root cause
> (maybe the one I pointed above) after this patch we will have the
> thermal driver to fail because "gpio" and "otpout" states are not
> defined nor documented (a change on this will need some reviews and
> acks and time I guess).

I definitly agree here. Handling + checking the binding change
as well as needed fallback code is definitly not material for -rc-kernels
so we should just revert for now and let Elaine fix the issues for 5.3.

Anyone volunteering for sending a revert-patch to Eduardo? :-)

Heiko

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