linux-kernel - Re: [PATCH V2 1/2] firmware: arm_scmi: Ensure that the message-id supports fastchannel

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Message-ID: <7d47081b-e7f8-4391-946a-f23e110976ec@kernel.org>
Date: Thu, 5 Sep 2024 14:54:02 +0200
From: Konrad Dybcio <konradybcio@...nel.org>
To: Cristian Marussi <cristian.marussi@....com>,
 Sudeep Holla <sudeep.holla@....com>
Cc: Konrad Dybcio <konradybcio@...nel.org>, Johan Hovold <johan@...nel.org>,
 Sibi Sankar <quic_sibis@...cinc.com>, linux-kernel@...r.kernel.org,
 arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH V2 1/2] firmware: arm_scmi: Ensure that the message-id
 supports fastchannel

On 4.09.2024 4:20 PM, Cristian Marussi wrote:
> On Wed, Sep 04, 2024 at 01:38:55PM +0100, Sudeep Holla wrote:
>> On Wed, Sep 04, 2024 at 01:29:29PM +0200, Konrad Dybcio wrote:
>>> On 4.09.2024 9:00 AM, Johan Hovold wrote:
>>
>> [...]
>>
>>>>
>>>> Unfortunately, this patch breaks resume from suspend on the x1e80100 crd:
>>>>
>>>>         [   26.919676] CPU4: Booted secondary processor 0x0000010000 [0x511f0011]
>>>>         [   26.960607] arm-scmi firmware:scmi: timed out in resp(caller: do_xfer+0x164/0x568)
>>>>         [   26.987142] cpufreq: cpufreq_online: ->get() failed
>>>>
>>>> and then the machine hangs (mostly, I saw an nvme timeout message after a
>>>> while).
>>>>
>>>> Make sure you test suspend as well as some of the warnings I reported
>>>> only show up during suspend.
>>>
>>> Eh it looks like PERF_LEVEL_GET (msgid 8) requires the use of FC, but
>>> the firmware fails to inform us about it through BIT(0) in attrs..
>>>
>>
>> Just trying to understand things better here. So the firmware expects OSPM
>> to just use FC only for PERF_LEVEL_GET and hence doesn't implement the
>> default/normal channel for PERF_LEVEL_GET(I assume it returns error ?)
>> but fails to set the attribute indicating FC is available for the domain.
>>
> 
> Is not that FCs are optional BUT PERF_LEVEL_GET standard messages is
> support is mandatory by the spec anyway ?

So doing a bit of poking I think it's that FC is not marked as supported,
but we need to read out the frequency from the .get_addr.. which is only
populated if we go through fastchannel_init

Konrad