linux-kernel - Re: [PATCH v4] mfd / platform: cros_ec: Query EC protocol version if EC transitions between RO/RW

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Date:   Mon, 16 Dec 2019 10:40:46 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Yicheng Li <yichengli@...omium.org>
Cc:     linux-kernel@...r.kernel.org, bleung@...omium.org,
        gwendal@...omium.org, enric.balletbo@...labora.com
Subject: Re: [PATCH v4] mfd / platform: cros_ec: Query EC protocol version if
 EC transitions between RO/RW

On Mon, 25 Nov 2019, Yicheng Li wrote:

> 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>
> ---
>  drivers/platform/chrome/cros_ec.c           | 24 +++++++++++++++++++++
>  include/linux/platform_data/cros_ec_proto.h |  3 +++
>  2 files changed, 27 insertions(+)

This is not an MFD patch.  Please drop it from the subject line.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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