linux-kernel - Re: [PATCH 1/3] input: misc: pm8941-pwrkey: add software key press debouncing support

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Message-ID: <CAE-0n51GUGskL17MGhk-=-dbdPU_3ChE37Hbzq6VBZc2Ge0vkA@mail.gmail.com>
Date:   Mon, 24 Jan 2022 11:33:53 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Anjelique Melendez <quic_amelende@...cinc.com>,
        dmitry.torokhov@...il.com
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, collinsd@...eaurora.org,
        bjorn.andersson@...aro.org, skakit@...eaurora.org
Subject: Re: [PATCH 1/3] input: misc: pm8941-pwrkey: add software key press
 debouncing support

Quoting Anjelique Melendez (2022-01-21 16:04:13)
>
>
> On 1/20/2022 8:08 PM, Stephen Boyd wrote:
> > Quoting Anjelique Melendez (2022-01-20 12:41:33)
> >> @@ -200,15 +268,21 @@ static int pm8941_pwrkey_probe(struct platform_device *pdev)
> >>                         dev_err(&pdev->dev, "failed to locate regmap\n");
> >>                         return -ENODEV;
> >>                 }
> >> +       }
> >>
> >> -               error = of_property_read_u32(parent->of_node,
> >> -                                            "reg", &pwrkey->baseaddr);
> >> -       } else {
> >> -               error = of_property_read_u32(pdev->dev.of_node, "reg",
> >> -                                            &pwrkey->baseaddr);
> >> +       addr = of_get_address(regmap_node, 0, NULL, NULL);
> >> +       if (!addr) {
> >> +               dev_err(&pdev->dev, "reg property missing\n");
> >> +               return -EINVAL;
> >> +       }
> >> +       pwrkey->baseaddr = be32_to_cpu(*addr);
> > Can this hunk be split off? A new API is used and it doesn't look
> > relevant to this patch.
>
> In PMK8350 and following chips the reg property will have the pon hlos address first,
> followed by a second pon pbs address. This change is needed so that both the older chipsets
> and the newer can be used regardless of how many reg addresses are being used.

Got it, but do we ned to change to of_get_address() in this patch? I was
suggesting that the change to the new API be done first so that it's
clearer what's going on with the change in address location.

>
> >
> >> +
> >> +       if (pwrkey->data->has_pon_pbs) {
> >> +               /* PON_PBS base address is optional */
> >> +               addr = of_get_address(regmap_node, 1, NULL, NULL);
> >> +               if (addr)
> >> +                       pwrkey->pon_pbs_baseaddr = be32_to_cpu(*addr);
> >>         }
> >> -       if (error)
> >> -               return error;
> >>
> >>         pwrkey->irq = platform_get_irq(pdev, 0);
> >>         if (pwrkey->irq < 0)
> >> @@ -217,7 +291,14 @@ static int pm8941_pwrkey_probe(struct platform_device *pdev)
> >>         error = regmap_read(pwrkey->regmap, pwrkey->baseaddr + PON_REV2,
> >>                             &pwrkey->revision);
> >>         if (error) {
> >> -               dev_err(&pdev->dev, "failed to set debounce: %d\n", error);
> >> +               dev_err(&pdev->dev, "failed to read revision: %d\n", error);
> > Nice error message fix!

This can be split off to a different patch as well.

> >
> >> +               return error;
> >> +       }
> >> +
> >> +       error = regmap_read(pwrkey->regmap, pwrkey->baseaddr + PON_SUBTYPE,
> >> +                           &pwrkey->subtype);
> >> +       if (error) {
> >> +               dev_err(&pdev->dev, "failed to read subtype: %d\n", error);
> >>                 return error;
> >>         }
> >>
> >> @@ -255,6 +336,12 @@ static int pm8941_pwrkey_probe(struct platform_device *pdev)
> >>                 }
> >>         }
> >>
> >> +       if (pwrkey->data->needs_sw_debounce) {
> >> +               error = pm8941_pwrkey_sw_debounce_init(pwrkey);
> >> +               if (error)
> >> +                       return error;
> >> +       }
> >> +
> >>         if (pwrkey->data->pull_up_bit) {
> >>                 error = regmap_update_bits(pwrkey->regmap,
> >>                                            pwrkey->baseaddr + PON_PULL_CTL,
> >> @@ -316,6 +403,8 @@ static const struct pm8941_data pwrkey_data = {
> >>         .phys = "pm8941_pwrkey/input0",
> >>         .supports_ps_hold_poff_config = true,
> >>         .supports_debounce_config = true,
> >> +       .needs_sw_debounce = true,
> > needs_sw_debounce is always true? Why is it even an option then?
>
> As of right now the "needs_sw_debounce" property is being used for a sw work around for a hw
> problem. We anticipate that chips in the future will fix this hw problem and we would then have
> devices where needs_sw_debounce would be set to false.

Hmm ok. Why can't future chips be supported in this series? What happens
if nobody ever adds support for the new chips? We're left with this
condition that looks like dead code.