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Subject: Re: [PATCH v10 10/10] Bluetooth: Add offload feature under
 experimental flag
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <CABBYNZJjjxzrSzLHwyzT-KyMOXYArrwVffHd6s=Kn-OLpTZhXQ@mail.gmail.com>
Date:   Thu, 22 Jul 2021 20:50:54 +0200
Cc:     Kiran K <kiran.k@intel.com>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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References: <20210630080807.12600-1-kiran.k@intel.com>
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To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Precedence: bulk

Hi Luiz,

>>>>>> Allow user level process to enable / disable codec offload
>>>>>> feature through mgmt interface. By default offload codec feature
>>>>>> is disabled.
>>>>>> 
>>>>>> Signed-off-by: Kiran K <kiran.k@intel.com>
>>>>>> Reviewed-by: Chethan T N <chethan.tumkur.narayan@intel.com>
>>>>>> Reviewed-by: Srivatsa Ravishankar <ravishankar.srivatsa@intel.com>
>>>>>> ---
>>>>>> * changes in v10:
>>>>>> - new patch added to place offload codec feature under experimental flag
>>>>>> 
>>>>>> include/net/bluetooth/hci.h |   4 ++
>>>>>> net/bluetooth/mgmt.c        | 106 +++++++++++++++++++++++++++++++++++-
>>>>>> net/bluetooth/sco.c         |  10 ++++
>>>>>> 3 files changed, 119 insertions(+), 1 deletion(-)
>>>>>> 
>>>>>> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
>>>>>> index e20318854900..5ca98d9f64dd 100644
>>>>>> --- a/include/net/bluetooth/hci.h
>>>>>> +++ b/include/net/bluetooth/hci.h
>>>>>> @@ -331,6 +331,10 @@ enum {
>>>>>>      HCI_CMD_PENDING,
>>>>>>      HCI_FORCE_NO_MITM,
>>>>>> 
>>>>>> +#if IS_ENABLED(CONFIG_BT_OFFLOAD_CODECS)
>>>>>> +       HCI_OFFLOAD_CODECS_ENABLED,
>>>>>> +#endif
>>>>> 
>>>>> That is probably a bad idea as it could lead the enum to assume
>>>>> different values based on what is enabled, besides we don't gain
>>>>> anything by not having the symbol defined all the time.
>>>> 
>>>> While this would work with dev_flags which are internal and not API, I still don’t like it.
>>>> 
>>>> There is really no benefit to make this a compile time option. And as far as I remember I never said this needs to be compile time. Actually I rather have this as an experimental setting so that it can be switched on at runtime. Nobody is going to recompile their kernels to test codec offload.
>>> 
>>> Initially I was with the same opinion, but the problem is the codecs
>>> are read at init sequence and the experimental flags are set at a
>>> later stage thus why I suggested a KConfig option until the feature is
>>> more mature and we can remove the option altogether.
>> 
>> I am fine with the codec options being read all the time. I mean having an experimental option to control the use of offload.
> 
> Alright, then we don't need the Kconfig after all, the experimental
> flag will only control the use of the codecs e.g. socketopts would not
> work if the flag is not enabled I assume?

exactly. It would then return EOPNOTSUPP error. It would be similar to an old kernel where this socket option is not available either.

Regards

Marcel