linux-kernel - Re: [PATCH V10 5/9] mfd: pm8008: Use i2c_new_dummy

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Date:   Mon, 18 Apr 2022 12:23:20 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Satya Priya Kakitapalli <quic_c_skakit@...cinc.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_collinsd@...cinc.com, quic_subbaram@...cinc.com,
        quic_jprakash@...cinc.com
Subject: Re: [PATCH V10 5/9] mfd: pm8008: Use i2c_new_dummy_device() API

Quoting Satya Priya Kakitapalli (Temp) (2022-04-18 08:08:33)
>
> On 4/15/2022 5:51 AM, Stephen Boyd wrote:
> > Quoting Satya Priya (2022-04-14 05:30:14)
> >> Use i2c_new_dummy_device() to register clients along with
> >> the main mfd device.
> > Why?
>
>
> As discussed on V9 of this series, I've done these changes.
>
> By using this API we can register other clients at different address
> space without having separate DT node.
>
> This avoids calling the probe twice for the same chip, once for each
> address space 0x8 and 0x9. I'll add this description in commit text.
>

Perfect, thanks.

>
> >> @@ -221,19 +236,38 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
> >>
> >>   static int pm8008_probe(struct i2c_client *client)
> >>   {
> >> -       int rc;
> >> +       int rc, i;
> >>          struct pm8008_data *chip;
> >> +       struct device_node *node = client->dev.of_node;
> >>
> >>          chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> >>          if (!chip)
> >>                  return -ENOMEM;
> >>
> >>          chip->dev = &client->dev;
> >> -       chip->regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
> >> -       if (!chip->regmap)
> >> -               return -ENODEV;
> >>
> >> -       i2c_set_clientdata(client, chip);
> >> +       for (i = 0; i < PM8008_NUM_CLIENTS; i++) {
> > This is 2. Why do we have a loop? Just register the i2c client for
> > pm8008_infra first and then make a dummy for the second address without
> > the loop and the indentation. Are there going to be more i2c clients?
>
>
> There wont be more than 2 clients, I can remove the loop, but then we
> will have repetitive code.. something like below

Repetitive code can be refactored into a subroutine.

>
>       chip->dev = &client->dev;
>       i2c_set_clientdata(client, chip);
>
>       regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg[0]);
>       if (!regmap)
>           return -ENODEV;
>
>
>       pm8008_client = i2c_new_dummy_device(client->adapter,
>                               client->addr + 1);
>       if (IS_ERR(pm8008_client)) {
>           dev_err(&pm8008_client->dev, "can't attach client\n");
>           return PTR_ERR(pm8008_client);
>       }
>       pm8008_client->dev.of_node = of_node_get(client->dev.of_node);
>       i2c_set_clientdata(pm8008_client, chip);
>
>       regulators_regmap = devm_regmap_init_i2c(pm8008_client,
> &qcom_mfd_regmap_cfg[1]);
>       if (!regmap)
>           return -ENODEV;
>
> >> diff --git a/include/linux/mfd/qcom_pm8008.h b/include/linux/mfd/qcom_pm8008.h
> >> new file mode 100644
> >> index 0000000..bc64f01
> >> --- /dev/null
> >> +++ b/include/linux/mfd/qcom_pm8008.h
> >> @@ -0,0 +1,13 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +#ifndef __QCOM_PM8008_H__
> >> +#define __QCOM_PM8008_H__
> >> +
> >> +#define PM8008_INFRA_SID       0
> >> +#define PM8008_REGULATORS_SID  1
> >> +
> >> +#define PM8008_NUM_CLIENTS     2
> >> +
> >> +struct pm8008_data;
> >> +struct regmap *pm8008_get_regmap(struct pm8008_data *chip, u8 sid);
> > Could this be avoided if the regulator driver used
> > dev_get_regmap(&pdev->dev.parent, "regulator") to find the regmap named
> > "regulator" of the parent device, i.e. pm8008-infra.
>
> I gave it a try, it didn't work. I could not get the regmap for
> regulators using pm8008-infra i.e., 0x8 device pointer.

Did it not work because the regmap config for the regulator config
didn't have a name?