linux-kernel - Re: [PATCH 04/14] wifi: ath10k: snoc: support powering on the device via pwrseq

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Message-ID: <CAO9ioeU2JjzDwkGQzxc963kakNyZCtaSRAmLu=1kOAMGQeuZRQ@mail.gmail.com>
Date: Fri, 2 Jan 2026 17:09:52 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Bartosz Golaszewski <brgl@...nel.org>
Cc: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Jeff Johnson <jjohnson@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Balakrishna Godavarthi <quic_bgodavar@...cinc.com>,
        Matthias Kaehlcke <mka@...omium.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, linux-wireless@...r.kernel.org,
        ath10k@...ts.infradead.org, linux-pm@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH 04/14] wifi: ath10k: snoc: support powering on the device
 via pwrseq

On Fri, 2 Jan 2026 at 13:07, Bartosz Golaszewski <brgl@...nel.org> wrote:
>
> On Wed, Dec 31, 2025 at 12:36 AM Dmitry Baryshkov
> <dmitry.baryshkov@....qualcomm.com> wrote:
> >
> > The WCN39xx family of WiFi/BT chips incorporates a simple PMU, spreading
> > voltages over internal rails. Implement support for using powersequencer
> > for this family of ATH10k devices in addition to using regulators.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> > ---
>
> [snip]
>
> >
> >  static void ath10k_snoc_wlan_disable(struct ath10k *ar)
> > @@ -1762,7 +1779,27 @@ static int ath10k_snoc_probe(struct platform_device *pdev)
> >                 goto err_release_resource;
> >         }
> >
> > -       ar_snoc->num_vregs = ARRAY_SIZE(ath10k_regulators);
> > +       /*
> > +        * Backwards compatibility, ignore the defer error from pwrseq, if it
> > +        * should be used, we will get an error from regulator get.
> > +        */
>
> Can you elaborate on this? I'm not exactly following. I suppose you
> mean the regulator_get() will return -EPROBE_DEFER? One of the
> supplies exposed by the PMU?

Yes. devm_pwrseq_get() can return -EPROBE_DEFER in two cases:
- it is not supposed to be used
- it is supposed to be used, but the driver hasn't probed yet.

There is no simple way to distinguish between these two cases, but:
- if it is not supposed to be used, then regulator_bulk_get() will
return all regulators as expected, continuing the probe
- if it is supposed to be used, but wasn't probed yet, we will get
-EPROBE_DEFER from regulator_bulk_get() too.

I can write that in a comment, if you think that it makes the code more obvious.

>
> Bart
>
> > +       ar_snoc->pwrseq = devm_pwrseq_get(&pdev->dev, "wlan");
> > +       if (IS_ERR(ar_snoc->pwrseq)) {
> > +               ret = PTR_ERR(ar_snoc->pwrseq);
> > +               ar_snoc->pwrseq = NULL;
> > +               if (ret != -EPROBE_DEFER)
> > +                       goto err_free_irq;
> > +
> > +               ar_snoc->num_vregs = ARRAY_SIZE(ath10k_regulators);
> > +       } else {
> > +               /*
> > +                * The first regulator (vdd-0.8-cx-mx) is used to power on part
> > +                * of the SoC rather than the PMU on WCN399x, the rest are
> > +                * handled via pwrseq.
> > +                */
> > +               ar_snoc->num_vregs = 1;
> > +       }
> > +



-- 
With best wishes
Dmitry