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Date: Wed, 5 Feb 2020 10:06:16 +0100
From: Enric Balletbo i Serra <enric.balletbo@...labora.com>
To: Gwendal Grignou <gwendal@...omium.org>,
Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Yicheng Li <yichengli@...omium.org>,
LKML <linux-kernel@...r.kernel.org>,
Benson Leung <bleung@...omium.org>,
Guenter Roeck <groeck@...omium.org>,
Lee Jones <lee.jones@...aro.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Evan Green <evgreen@...omium.org>,
Rushikesh S Kadam <rushikesh.s.kadam@...el.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v6] platform/chrome: cros_ec: Query EC protocol version if
EC transitions between RO/RW
Hi,
On 4/2/20 21:40, Gwendal Grignou wrote:
> Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
>
> On Mon, Feb 3, 2020 at 11:30 PM Marek Szyprowski
> <m.szyprowski@...sung.com> wrote:
>>
>> Hi
>>
>> On 03.02.2020 23:53, 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>
>>
>> Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
>>
>> Works fine on Samsung Exynos-based Chromebooks: Snow, Peach-Pit and
>> Peach-Pi.
>>
Thanks, we will pick this patch once 5.6-rc1 is out. For my own reference:
Acked-for-chrome-platform: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>>> ---
>>> Hi Enric and Marek,
>>>
>>>> This patch landed recently in linux-next as commit
>>>> 241a69ae8ea8e2defec751fe55dac1287aa044b8. Sadly, it causes following
>>>> kernel oops on any key press on Samsung Exynos-based Chromebooks (Snow,
>>>> Peach-Pit and Peach-Pi):
>>>
>>>> Many thanks for report the issue, we will take a look ASAP and revert
>>>> this commit meanwhile.
>>>
>>>> Simply removing the BUG_ON() from cros_ec_get_host_event() function
>>>> fixes the issue, but I don't know the protocol details to judge if this
>>>> is the correct way of fixing it.
>>> The issue was those Samsung Chromebooks (Snow, Peach-Pit and Peach-Pi)
>>> do not support mkbp events, yet we applied the same thing to them, which
>>> we shouldn't. This v6 should fix it: I Just added a check
>>>
>>> if (ec_dev->mkbp_event_supported)
>>>
>>> in cros_ec_register().
>>>
>>>
>>>
>>> drivers/platform/chrome/cros_ec.c | 29 +++++++++++++++++++++
>>> include/linux/platform_data/cros_ec_proto.h | 3 +++
>>> 2 files changed, 32 insertions(+)
>>>
>>> diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
>>> index 9b2d07422e17..f16804db805b 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 +218,18 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>>> dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
>>> err);
>>>
>>> + if (ec_dev->mkbp_event_supported) {
>>> + /*
>>> + * 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;
>>
>> Best regards
>> --
>> Marek Szyprowski, PhD
>> Samsung R&D Institute Poland
>>
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