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From: Jaganath K <jaganath.k.os@gmail.com>
Date: Mon, 19 Feb 2018 15:39:06 +0530
Message-ID: <CAJzH+bok8hZ5y3VjTS3Hx9gqPYMJ3_9bcuqZJr9-agD3tqCOTg@mail.gmail.com>
Subject: Re: [PATCH 2/4 v4] doc/mgmt-api: Add support for Set Phy
 Configuration command
To: =?UTF-8?Q?=C5=81ukasz_Rymanowski?= <lukasz.rymanowski@codecoup.pl>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
        Jaganath Kanakkassery <jaganathx.kanakkassery@intel.com>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Lukasz,

On Mon, Feb 19, 2018 at 3:28 PM, =C5=81ukasz Rymanowski
<lukasz.rymanowski@codecoup.pl> wrote:
> Hi Jaganath,
>
> On 19 February 2018 at 10:25, Jaganath K <jaganath.k.os@gmail.com> wrote:
>> Hi Luiz,
>>
>>
>> On Mon, Feb 19, 2018 at 2:17 PM, Luiz Augusto von Dentz
>> <luiz.dentz@gmail.com> wrote:
>>> Hi Jaganath,
>>>
>>> On Fri, Feb 16, 2018 at 5:40 AM, Jaganath K <jaganath.k.os@gmail.com> w=
rote:
>>>> Hi Marcel,
>>>>
>>>>
>>>> On Wed, Nov 29, 2017 at 12:22 PM, Jaganath Kanakkassery
>>>> <jaganath.k.os@gmail.com> wrote:
>>>>> This also adds PHY Configuration Changed Event.
>>>>> ---
>>>>>  doc/mgmt-api.txt | 52 ++++++++++++++++++++++++++++++++++++++++++++++=
++++++
>>>>>  1 file changed, 52 insertions(+)
>>>>>
>>>>> diff --git a/doc/mgmt-api.txt b/doc/mgmt-api.txt
>>>>> index c07c48c..628ff18 100644
>>>>> --- a/doc/mgmt-api.txt
>>>>> +++ b/doc/mgmt-api.txt
>>>>> @@ -2940,9 +2940,46 @@ Get PHY Configuration Command
>>>>>         LE 1M TX and LE 1M RX would be supported by default.
>>>>>
>>>>>         This command is only available for LE capable controllers.
>>>>> +        It will return Not Supported otherwise.
>>>>> +
>>>>> +        Possible errors:        Not Supported
>>>>> +                               Invalid Index
>>>>> +
>>>>> +Set PHY Configuration Command
>>>>> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
>>>>> +
>>>>> +       Command Code:           0x0044
>>>>> +       Controller Index:       <controller id>
>>>>> +       Command Parameters:     Default_phys (2 Octet)
>>>>> +       Return Parameters:
>>>>> +
>>>>> +       This command is used to set the default phy to the controller=
.
>>>>> +
>>>>> +       This will be stored and used for all the subsequent scanning
>>>>> +       and connection initiation.
>>>>> +
>>>>> +       The list of supported PHYs can be retrieved via the
>>>>> +       Get PHY Configuration command. Selecting unsupported PHYs wil=
l
>>>>> +       result in an Invalid Parameters error.
>>>>> +
>>>>> +       This can be called at any point to change the preferred PHYs.
>>>>> +
>>>>> +       Default_phy is a bitmask with the following bits.
>>>>> +               0       LE 1M TX
>>>>> +               1       LE 1M RX
>>>>> +               2       LE 2M TX
>>>>> +               3       LE 2M RX
>>>>> +               4       LE CODED TX
>>>>> +               5       LE CODED RX
>>>>> +
>>>>> +       This command generates a Command Complete event on success
>>>>> +       or a Command Status event on failure.
>>>>> +
>>>>> +       This command is only available for LE capable controllers.
>>>>>         It will return Not Supported otherwise.
>>>>>
>>>>>         Possible errors:        Not Supported
>>>>> +                               Invalid Parameters
>>>>>                                 Invalid Index
>>>>>
>>>>
>>>> I think there is a limitation with current API proposal, user cannot d=
o extended
>>>> scanning in only 1M (to scan secondary channel in 1M) since with 1M we=
 will
>>>> switch to legacy scanning.
>>>
>>> Why do we have to switch to legacy scanning for 1M? It seems it would
>>> be possible to use extended scanning whenever it is supported
>>> regardless of the PHY, or perhaps the spec imposes limitations to
>>> certain PHYs? Coded perhaps?
>>>
>>
>> The idea is to enable application to use legacy scanning even if
>> controller supports
>> extended. (ie if application dont want extended features to be used)
>> and unlike advertising
>> legacy scanning can not be emulated using extended scanning.
>
> Bluetooth controller which is doing extended scanning will report legacy
> advertisings as well. It will just use Extended Advertising Report
> Event for this purpose and Linux Kernel should handle it.
>

Yes, but the idea here is more on perspective of power savings
where in application dont want to scan on secondary channels itself and
API should support it.

Thanks,
Jaganath