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Date: Mon, 1 Apr 2024 15:06:56 +0200
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Subject: Re: Linux logs error: `mei_me 0000:00:16.0: cl:host=04 me=00 is not
 connected`
To: Alexander Usyskin <alexander.usyskin@intel.com>,
 Tomas Winkler <tomas.winkler@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>
References: <4c785706-2961-4eac-b5d7-2cf89c195969@molgen.mpg.de>
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From: Paul Menzel <pmenzel@molgen.mpg.de>
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Dear Alexander,


Thank you very much for your reply.

Am 01.04.24 um 08:54 schrieb Usyskin, Alexander:
>> -----Original Message-----

>> Sent: Saturday, March 30, 2024 13:56
>> Am 30.03.24 um 11:50 schrieb Winkler, Tomas:
>>>
>>>> -----Original Message-----
>>>> From: Paul Menzel <pmenzel@molgen.mpg.de>
>>>> Sent: Friday, March 29, 2024 12:49 PM
>>
>> […]
>>
>>>> On a Dell XPS 13 9360/0596KF, BIOS 2.21.0 06/02/2022 with Debian
>>>> sid/unstable and self-built Linux 6.9-rc1+ with one patch on top [1] and
>>>> KASAN enabled.
>>>>
>>>>        $ git log --no-decorate --oneline -2 a2ce022afcbb
>>>>        a2ce022afcbb [PATCH] kbuild: Disable KCSAN for autogenerated *.mod.c intermediaries
>>>>        8d025e2092e2 Merge tag 'erofs-for-6.9-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
>>>>
>>>> After several ACPI S3 (deep) suspend and resume cycles, this morning I
>>>> noticed the error below:
>>>>
>>>>        [29357.177635] mei_me 0000:00:16.0: cl:host=04 me=00 is not connected
>>>>
>>>> This seems to be logged from `mei_write()` in `drivers/misc/mei/main.c`.
>>>>
>>>>        if (!mei_cl_is_connected(cl)) {
>>>>        	cl_err(dev, cl, "is not connected");
>>>>        	rets = -ENODEV;
>>>>        	goto out;
>>>>        }
>>>>
>>>> with `drivers/misc/mei/client.h` containing:
>>>>
>>>>        /**
>>>>         * mei_cl_is_connected - host client is connected
>>>>         *
>>>>         * @cl: host client
>>>>         *
>>>>         * Return: true if the host client is connected
>>>>         */
>>>>        static inline bool mei_cl_is_connected(const struct mei_cl *cl)
>>>>        {
>>>>        	return  cl->state == MEI_FILE_CONNECTED;
>>>>        }
>>>>
>>>> Unfortunately, I do not know at all, why the ME needs to be written to, and
>>>> what was tried to be written, and what the effect of this failure is.
>>>>
>>>> Could you please take a look at it?
>>>
>>> Looks like a timing issue between setting up HDCP by graphics and
>>> device power management.  I don't think this is a really an issue if
>>> this is happening during power cycles stress.
>>
>> Understood. Could this be because of the Address Sanitizer (KASAN)?
>>
>>> Anyway we will look at that, will you be able to provide more debug
>>> information if we ask for it?
>> 
>> Thank you. Yes, I can test patches. But right now, I was only able to
>> see this once, so I am not sure how to reproduce it.
> 
> This print is in the code path executed from user-space only. Seem
> like some user space app have had connection opened before suspend 
> and tried to write after resume, but driver closed all connections on
> suspend. This is normal flow; user space should reopen handle and
> retry in this case.

Interesting. Would user space program could this be?

> The print can be demoted to debug, I think.

Understood. Still maybe it could be extended too, so the cause/solution 
could be deduced from the Linux logs.


Kind regards,

Paul


PS: Only if you care:

> --
> Alexander (Sasha) Usyskin

Your signature delimiter misses a trailing space at the end [1].


[1]: https://en.wikipedia.org/wiki/Signature_block#Standard_delimiter