linux-kernel - Re: [PATCH v7 7/7] cros_ec: differentiate SCP from EC by feature bit.

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Message-ID: <CAFqH_50sRWxYAy3tvFMPkce_NQSSqwT8z7-ASgiba2RxQ8DqdA@mail.gmail.com>
Date:   Thu, 28 Mar 2019 11:54:32 +0100
From:   Enric Balletbo Serra <eballetbo@...il.com>
To:     Peter Shih <pihsun@...omium.org>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Benson Leung <bleung@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Guenter Roeck <groeck@...omium.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 7/7] cros_ec: differentiate SCP from EC by feature bit.

Hi,

Thanks for submitting this upstream. Some few comments below.

Please prepend the subsystem for the commit. I.e:

mfd: cros_ec: differentiate SCP from EC by feature bit.

Missatge de Peter Shih <pihsun@...omium.org> del dia dc., 27 de març
2019 a les 6:18:
>
> From: Pi-Hsun Shih <pihsun@...omium.org>
>
> Since a SCP and EC would both exist on a system, and use the cros_ec_dev

Could you also explain what an SCP is?

> driver, we need to differentiate between them for the userspace, or they
> would both be registered at /dev/cros_ec, causing a conflict.
>
> Signed-off-by: Pi-Hsun Shih <pihsun@...omium.org>
> ---
> Changes from v6:
>  - No change.
>
> Changes from v5:
>  - No change.
>
> Changes from v4:
>  - No change.
>
> Changes from v3:
>  - No change.
>
> Changes from v2:
>  - No change.
>
> Changes from v1:
>  - New patch extracted from Patch 5.
> ---
>  drivers/mfd/cros_ec_dev.c            | 10 ++++++++++
>  include/linux/mfd/cros_ec.h          |  1 +
>  include/linux/mfd/cros_ec_commands.h |  2 ++
>  3 files changed, 13 insertions(+)
>
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index d275deaecb12..da2f2145d31d 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -418,6 +418,16 @@ static int ec_device_probe(struct platform_device *pdev)
>         device_initialize(&ec->class_dev);
>         cdev_init(&ec->cdev, &fops);
>
> +       /* check whether this is actually a SCP rather than an EC */

Capitalize the phrase.

> +       if (cros_ec_check_features(ec, EC_FEATURE_SCP)) {
> +               dev_info(dev, "SCP detected.\n");

dev_info(dev, "CrOS SCP MCU detected.\n")

To be coherent with other messages like this that are already sent upstream.

> +               /*
> +                * Help userspace differentiating ECs from SCP,
> +                * regardless of the probing order.
> +                */
> +               ec_platform->ec_name = CROS_EC_DEV_SCP_NAME;
> +       }
> +
>         /*
>          * Add the class device
>          * Link to the character device for creating the /dev entry
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 8f2a8918bfa3..a971399bad82 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -24,6 +24,7 @@
>
>  #define CROS_EC_DEV_NAME "cros_ec"
>  #define CROS_EC_DEV_PD_NAME "cros_pd"
> +#define CROS_EC_DEV_SCP_NAME "cros_scp"
>
>  /*
>   * The EC is unresponsive for a time after a reboot command.  Add a
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index fc91082d4c35..3e5da6e93b2f 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h

Remove this change and base your work on top of [1]

> @@ -856,6 +856,8 @@ enum ec_feature_code {
>         EC_FEATURE_RTC = 27,
>         /* EC supports CEC commands */
>         EC_FEATURE_CEC = 35,
> +       /* The MCU exposes a SCP */
> +       EC_FEATURE_SCP = 39,
>  };
>
>  #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32))
> --
> 2.21.0.392.gf8f6787159e-goog
>
Thanks,
 Enric

[1] https://lkml.org/lkml/2019/2/27/723