linux-kernel - Re: [PATCH v3 2/3] HID: i2c-hid: Allow subclasses of i2c-hid for power sequencing

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Date:   Mon, 2 Nov 2020 19:46:34 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Jiri Kosina <jkosina@...e.cz>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Linux Input <linux-input@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Kai Heng Feng <kai.heng.feng@...onical.com>,
        andrea@...gia.bo.it, Aaron Ma <aaron.ma@...onical.com>,
        Daniel Playfair Cal <daniel.playfair.cal@...il.com>,
        Jiri Kosina <jikos@...nel.org>, Pavel Balan <admin@...ma.net>,
        You-Sheng Yang <vicamo.yang@...onical.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] HID: i2c-hid: Allow subclasses of i2c-hid for
 power sequencing

On Mon, Nov 2, 2020 at 6:13 PM Douglas Anderson <dianders@...omium.org> wrote:
>
> This exports some things from i2c-hid so that we can have a driver
> that's effectively a subclass of it and that can do its own power
> sequencing.
>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
>
> Changes in v3:
> - Rework to use subclassing.
>
> Changes in v2:
> - Use a separate compatible string for this new touchscreen.
> - Get timings based on the compatible string.
>
>  drivers/hid/i2c-hid/i2c-hid-core.c    | 78 +++++++++++++++++----------
>  include/linux/input/i2c-hid-core.h    | 19 +++++++
>  include/linux/platform_data/i2c-hid.h |  9 ++++
>  3 files changed, 79 insertions(+), 27 deletions(-)
>  create mode 100644 include/linux/input/i2c-hid-core.h
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
> index 786e3e9af1c9..910e9089fcf8 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> @@ -22,6 +22,7 @@
>  #include <linux/i2c.h>
>  #include <linux/interrupt.h>
>  #include <linux/input.h>
> +#include <linux/input/i2c-hid-core.h>
>  #include <linux/irq.h>
>  #include <linux/delay.h>
>  #include <linux/slab.h>
> @@ -1007,8 +1008,33 @@ static void i2c_hid_fwnode_probe(struct i2c_client *client,
>                 pdata->post_power_delay_ms = val;
>  }
>
> -static int i2c_hid_probe(struct i2c_client *client,
> -                        const struct i2c_device_id *dev_id)
> +static int i2c_hid_power_up_device(struct i2c_hid_platform_data *pdata)
> +{
> +       struct i2c_hid *ihid = container_of(pdata, struct i2c_hid, pdata);
> +       struct hid_device *hid = ihid->hid;
> +       int ret;
> +
> +       ret = regulator_bulk_enable(ARRAY_SIZE(pdata->supplies),
> +                                   pdata->supplies);
> +       if (ret) {
> +               if (hid)
> +                       hid_warn(hid, "Failed to enable supplies: %d\n", ret);
> +               return ret;
> +       }
> +
> +       if (pdata->post_power_delay_ms)
> +               msleep(pdata->post_power_delay_ms);
> +
> +       return 0;
> +}
> +
> +static void i2c_hid_power_down_device(struct i2c_hid_platform_data *pdata)
> +{
> +       regulator_bulk_disable(ARRAY_SIZE(pdata->supplies), pdata->supplies);
> +}
> +
> +int i2c_hid_probe(struct i2c_client *client,
> +                 const struct i2c_device_id *dev_id)
>  {
>         int ret;
>         struct i2c_hid *ihid;
> @@ -1035,6 +1061,9 @@ static int i2c_hid_probe(struct i2c_client *client,
>         if (!ihid)
>                 return -ENOMEM;
>
> +       if (platform_data)
> +               ihid->pdata = *platform_data;
> +
>         if (client->dev.of_node) {
>                 ret = i2c_hid_of_probe(client, &ihid->pdata);
>                 if (ret)
> @@ -1043,13 +1072,16 @@ static int i2c_hid_probe(struct i2c_client *client,
>                 ret = i2c_hid_acpi_pdata(client, &ihid->pdata);
>                 if (ret)
>                         return ret;
> -       } else {
> -               ihid->pdata = *platform_data;
>         }
>
>         /* Parse platform agnostic common properties from ACPI / device tree */
>         i2c_hid_fwnode_probe(client, &ihid->pdata);
>
> +       if (!ihid->pdata.power_up_device)
> +               ihid->pdata.power_up_device = i2c_hid_power_up_device;
> +       if (!ihid->pdata.power_down_device)
> +               ihid->pdata.power_down_device = i2c_hid_power_down_device;
> +
>         ihid->pdata.supplies[0].supply = "vdd";
>         ihid->pdata.supplies[1].supply = "vddl";
>
> @@ -1059,14 +1091,10 @@ static int i2c_hid_probe(struct i2c_client *client,
>         if (ret)
>                 return ret;
>
> -       ret = regulator_bulk_enable(ARRAY_SIZE(ihid->pdata.supplies),
> -                                   ihid->pdata.supplies);
> -       if (ret < 0)
> +       ret = ihid->pdata.power_up_device(&ihid->pdata);
> +       if (ret)

This is an odd driver structure IMO. I guess platform data is already
there, but that's not what we'd use for any new driver.

Why not export i2c_hid_probe, i2c_hid_remove, etc. and then just call
them from the goodix driver and possibly make it handle all DT
platforms?

Who else needs regulators besides DT platforms? I thought with ACPI
it's all wonderfully abstracted away?

Rob