linux-kernel - Re: [PATCH 1/3] drivers: thermal: tsens: Add critical interrupt support

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Date:   Fri, 29 Nov 2019 00:16:33 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Stephen Boyd <swboyd@...omium.org>, sivaa@...eaurora.org,
        Andy Gross <agross@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 1/3] drivers: thermal: tsens: Add critical interrupt support

On Wed, Nov 13, 2019 at 1:08 AM Bjorn Andersson
<bjorn.andersson@...aro.org> wrote:
>
> On Mon 11 Nov 11:21 PST 2019, Amit Kucheria wrote:
>
> > TSENS IP v2.x adds critical threshold interrupt support for each sensor
> > in addition to the upper/lower threshold interrupt. Add support in the
> > driver.
> >
> > Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> > ---
> >  drivers/thermal/qcom/tsens-common.c | 129 ++++++++++++++++++++++++++--
> >  drivers/thermal/qcom/tsens-v2.c     |   8 +-
> >  drivers/thermal/qcom/tsens.c        |  21 +++++
> >  drivers/thermal/qcom/tsens.h        |  73 ++++++++++++++++
> >  4 files changed, 220 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/thermal/qcom/tsens-common.c b/drivers/thermal/qcom/tsens-common.c
> > index 4359a4247ac3..2989cb952cdb 100644
> > --- a/drivers/thermal/qcom/tsens-common.c
> > +++ b/drivers/thermal/qcom/tsens-common.c
> > @@ -23,6 +23,10 @@
> >   * @low_thresh:     lower threshold temperature value
> >   * @low_irq_mask:   mask register for lower threshold irqs
> >   * @low_irq_clear:  clear register for lower threshold irqs
> > + * @crit_viol:      critical threshold violated
>
> "violated" as in "temperature is above crit_thresh"?

Yes.

>
> > + * @crit_thresh:    critical threshold temperature value
> > + * @crit_irq_mask:  mask register for critical threshold irqs
> > + * @crit_irq_clear: clear register for critical threshold irqs
> >   *
> [..]
> > diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c
> > index 7d317660211e..784c4976c4f9 100644
> > --- a/drivers/thermal/qcom/tsens.c
> > +++ b/drivers/thermal/qcom/tsens.c
> > @@ -121,6 +121,27 @@ static int tsens_register(struct tsens_priv *priv)
> >
> >       enable_irq_wake(irq);
> >
> > +     if (tsens_version(priv) > VER_1_X) {
> > +             irq = platform_get_irq_byname(pdev, "critical");
> > +             if (irq < 0) {
>
> Treating this as a fatal error breaks backwards compatibility with
> current devicetree; and even within your patch series, tsens should fail
> to probe between this patch and the application of patch 3.

Good catch.

> Please flip this around and do:
>
> irq = platform_get_irq_byname(pdev, "critical");
> if (irq >= 0 && tsens_version(priv) > VER_1_X) {
>         request_irq()...
> }

Won't this still break with current devicetree since irq < 0 until
patch 3? Or are you saying we shouldn't check for
platform_get_irq_byname() failure?

I can see two ways out:
1. We patch the dtsi before the code change.
2. We make critical interrupt failure non-fatal by just printing some
messages and still returning success.

Regards,
Amit


> > +                     ret = irq;
> > +                     goto err_put_device;
> > +             }
> > +
> > +             ret = devm_request_threaded_irq(&pdev->dev, irq,
> > +                                             NULL, tsens_critical_irq_thread,
> > +                                             IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> > +                                             dev_name(&pdev->dev), priv);
> > +             if (ret) {
> > +                     dev_err(&pdev->dev, "%s: failed to get critical irq\n", __func__);
> > +                     goto err_put_device;
> > +             }
> > +
> > +             enable_irq_wake(irq);
> > +     }
> > +
> > +     return 0;
> > +
> >  err_put_device:
> >       put_device(&pdev->dev);
> >       return ret;
>
> Regards,
> Bjorn