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

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Message-ID: <b5149024683189b78224f4c6639818e9d833e126.camel@collabora.com>
Date:   Thu, 16 Jan 2020 13:27:15 +0100
From:   Fabien Lahoudere <fabien.lahoudere@...labora.com>
To:     Yicheng Li <yichengli@...omium.org>, linux-kernel@...r.kernel.org
Cc:     bleung@...omium.org, gwendal@...omium.org,
        enric.balletbo@...labora.com
Subject: Re: [PATCH] mfd / platform: cros_ec: Query EC protocol version if
 EC transitions between RO/RW

Hi,

I tried to test that patch but I cannot switch to RO firmware.
I do the following steps:

root@...ian:/sys/class/chromeos/cros_fp# cat version 
RO version:    nocturne_fp_v2.2.64-58cf5974e
RW version:    nocturne_fp_v2.2.110-b936c0a3c
Firmware copy: RW
Build info:    nocturne_fp_v2.2.110-b936c0a3c 2018-11-02 14:16:46
@swarm-cros-461
Chip vendor:   stm
Chip name:     stm32h7x3
Chip revision: 
Board version: EC error 1
root@...ian:/sys/class/chromeos/cros_fp# echo ro > reboot
root@...ian:/sys/class/chromeos/cros_fp# cat version 
RO version:    nocturne_fp_v2.2.64-58cf5974e
RW version:    nocturne_fp_v2.2.110-b936c0a3c
Firmware copy: RW
Build info:    nocturne_fp_v2.2.110-b936c0a3c 2018-11-02 14:16:46
@swarm-cros-461
Chip vendor:   stm
Chip name:     stm32h7x3
Chip revision: 
Board version: EC error 1
root@...ian:/sys/class/chromeos/cros_fp#

We see here that cros_fp is still RW.

I also tried with:

debian@...ian:/src/ec$ sudo build/bds/util/ectool --name=cros_fp
reboot_ec RO
debian@...ian:/src/ec$ sudo build/bds/util/ectool --name=cros_fp
version     
RO version:    nocturne_fp_v2.2.64-58cf5974e
RW version:    nocturne_fp_v2.2.110-b936c0a3c
Firmware copy: RW
Build info:    nocturne_fp_v2.2.110-b936c0a3c 2018-11-02 14:16:46
@swarm-cros-461
Tool version:  v2.0.3074-a5052d4e7 2020-01-16 10:23:05 debian@...ian
debian@...ian:/src/ec$

with the same result.

Can you decribe us steps you follow to test that patch?

Thanks

Fabien

Le lundi 18 novembre 2019 à 12:00 -0800, Yicheng Li a écrit :
> 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.
> 
> Signed-off-by: Yicheng Li <yichengli@...omium.org>
> 
> Change-Id: Ib58032ff4a8e113bdbd07212e8aff42807afff38
> Series-to: LKML <linux-kernel@...r.kernel.org>
> Series-cc: Benson Leung <bleung@...omium.org>, Enric Balletbo i Serra
> <enric.balletbo@...labora.com>, Gwendal Grignou <gwendal@...omium.org
> >
> ---
>  drivers/platform/chrome/cros_ec.c           | 24
> +++++++++++++++++++++
>  include/linux/platform_data/cros_ec_proto.h |  1 +
>  2 files changed, 25 insertions(+)
> 
> diff --git a/drivers/platform/chrome/cros_ec.c
> b/drivers/platform/chrome/cros_ec.c
> index 9b2d07422e17..0c910846d99d 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;
> +	} else {
> +		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 < 0)
> +		dev_warn(ec_dev->dev, "Failed to register notifier\n");
> +
>  	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..9840408c0b01 100644
> --- a/include/linux/platform_data/cros_ec_proto.h
> +++ b/include/linux/platform_data/cros_ec_proto.h
> @@ -161,6 +161,7 @@ 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;