linux-kernel - Re: [PATCH v5] platform: cros_ec: Query EC protocol version if EC transitions between RO/RW

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Message-ID: <CAFqH_538ncoNMuSZoC9VfT9fV_NUd7GhGd2q0D0-ag-V9Cpw3A@mail.gmail.com>
Date:   Thu, 23 Jan 2020 22:04:58 +0100
From:   Enric Balletbo Serra <eballetbo@...il.com>
To:     Yicheng Li <yichengli@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Benson Leung <bleung@...omium.org>,
        Gwendal Grignou <gwendal@...omium.org>
Subject: Re: [PATCH v5] platform: cros_ec: Query EC protocol version if EC
 transitions between RO/RW

Hi Yicheng,

Missatge de Yicheng Li <yichengli@...omium.org> del dia dt., 7 de gen.
2020 a les 23:10:
>
> RO and RW of EC may have different EC protocol version. If EC transitions
> between RO and RW, but AP does not reboot (this is true for fingerprint
> microcontroller / cros_fp, but not true for main ec / cros_ec), the AP
> still uses the protocol version queried before transition, which can
> cause problems. In the case of fingerprint microcontroller, this causes
> AP to send the wrong version of EC_CMD_GET_NEXT_EVENT to RO in the
> interrupt handler, which in turn prevents RO to clear the interrupt
> line to AP, in an infinite loop.
>
> Once an EC_HOST_EVENT_INTERFACE_READY is received, we know that there
> might have been a transition between RO and RW, so re-query the protocol.
>
> Change-Id: I49a51cc10d22a4ab9e75204a4c0c8819d5b3d282

I changed the subject to 'platform/chrome' and removed the Change-id line

> Signed-off-by: Yicheng Li <yichengli@...omium.org>

And added the Fabien's Tested-by tag

> ---
>  drivers/platform/chrome/cros_ec.c           | 24 +++++++++++++++++++++
>  include/linux/platform_data/cros_ec_proto.h |  3 +++

Fixed a trivial conflict with current chrome-platform tree and applied for-next.

Please remember to cc all the maintainers and maintain a changelog
between version next time.

Thanks,
 Enric


>  2 files changed, 27 insertions(+)
>
> diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
> index 9b2d07422e17..38ec1fb409a5 100644
> --- a/drivers/platform/chrome/cros_ec.c
> +++ b/drivers/platform/chrome/cros_ec.c
> @@ -104,6 +104,23 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
>         return ret;
>  }
>
> +static int cros_ec_ready_event(struct notifier_block *nb,
> +       unsigned long queued_during_suspend, void *_notify)
> +{
> +       struct cros_ec_device *ec_dev = container_of(nb, struct cros_ec_device,
> +                                                    notifier_ready);
> +       u32 host_event = cros_ec_get_host_event(ec_dev);
> +
> +       if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_INTERFACE_READY)) {
> +               mutex_lock(&ec_dev->lock);
> +               cros_ec_query_all(ec_dev);
> +               mutex_unlock(&ec_dev->lock);
> +               return NOTIFY_OK;
> +       }
> +
> +       return NOTIFY_DONE;
> +}
> +
>  /**
>   * cros_ec_register() - Register a new ChromeOS EC, using the provided info.
>   * @ec_dev: Device to register.
> @@ -201,6 +218,13 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>                 dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
>                         err);
>
> +       /* Register the notifier for EC_HOST_EVENT_INTERFACE_READY event. */
> +       ec_dev->notifier_ready.notifier_call = cros_ec_ready_event;
> +       err = blocking_notifier_chain_register(&ec_dev->event_notifier,
> +                                              &ec_dev->notifier_ready);
> +       if (err)
> +               return err;
> +
>         dev_info(dev, "Chrome EC device registered\n");
>
>         return 0;
> diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
> index 0d4e4aaed37a..a1c545c464e7 100644
> --- a/include/linux/platform_data/cros_ec_proto.h
> +++ b/include/linux/platform_data/cros_ec_proto.h
> @@ -121,6 +121,8 @@ struct cros_ec_command {
>   * @event_data: Raw payload transferred with the MKBP event.
>   * @event_size: Size in bytes of the event data.
>   * @host_event_wake_mask: Mask of host events that cause wake from suspend.
> + * @notifier_ready: The notifier_block to let the kernel re-query EC
> + *      communication protocol when the EC sends EC_HOST_EVENT_INTERFACE_READY.
>   * @ec: The platform_device used by the mfd driver to interface with the
>   *      main EC.
>   * @pd: The platform_device used by the mfd driver to interface with the
> @@ -161,6 +163,7 @@ struct cros_ec_device {
>         int event_size;
>         u32 host_event_wake_mask;
>         u32 last_resume_result;
> +       struct notifier_block notifier_ready;
>
>         /* The platform devices used by the mfd driver */
>         struct platform_device *ec;
> --
> 2.21.0
>