[Bluez-devel] want duplicate inquiry results during a single device inquiry

[Bluez-devel] want duplicate inquiry results during a single device inquiry

[Albert Huang]

Hello,

While experimenting with a hp ipaq running a 2.4.19 kernel, I noticed
that during a since device inquiry, multiple EVT_INQUIRY_RESULT events
could be generated from the same remote device.  The inquiry was done
using a raw hci socket.  On x86 PCs running the same userland code but
with more recent versions of bluez and the linux kernel, the duplicate
events are no longer generated.  Instead, during a single inquiry, a
response will be received from a remote device at most once.

I'm assuming that sometime in the recent past, kernel level caching
was implemented to prevent these duplicate inquiry results from
propagating up to user land.  Is there a way to turn this off, so that
all inquiry results are passed through?

Thanks!
-albert


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Re: [Bluez-devel] want duplicate inquiry results during a single device inquiry

[Marcel Holtmann]

Hi Albert,

> While experimenting with a hp ipaq running a 2.4.19 kernel, I noticed
> that during a since device inquiry, multiple EVT_INQUIRY_RESULT events
> could be generated from the same remote device.  The inquiry was done
> using a raw hci socket.  On x86 PCs running the same userland code but
> with more recent versions of bluez and the linux kernel, the duplicate
> events are no longer generated.  Instead, during a single inquiry, a
> response will be received from a remote device at most once.
> 
> I'm assuming that sometime in the recent past, kernel level caching
> was implemented to prevent these duplicate inquiry results from
> propagating up to user land.  Is there a way to turn this off, so that
> all inquiry results are passed through?

this is device specific and can be controlled by a HCI command. Show us
the outputs of "hciconfig -a" for both devices.

Regards

Marcel




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Re: Re: [Bluez-devel] want duplicate inquiry results during a single device inquiry

[Albert Huang]

on the HP iPAQ h5550:
# hciconfig -a
hci0:   Type: UART
        BD Address: 08:00:17:1B:0A:21 ACL MTU: 339:4  SCO MTU: 60:9
        UP RUNNING PSCAN ISCAN
        RX bytes:84 acl:0 sco:0 events:10 errors:1
        TX bytes:298 acl:0 sco:0 commands:10 errors:0
        Features: 0x00 0x00 0x00 0x00
        Packet type: DM1 DH1 HV1
        Link policy: HOLD SNIFF PARK
        Link mode: SLAVE ACCEPT
        Name: 'familiar (0)'
        Class: 0x120112
        Service Classes: Networking, Object Transfer
        Device Class: Computer, Handheld
        HCI Ver: 1.1 (0x1) HCI Rev: 0x180 LMP Ver: 1.1 (0x1) LMP Subver: 0x180
        Manufacturer: RTX Telecom A/S (21)

on the desktop (d-link DBT-120):
# hciconfig -a
hci0:   Type: USB
        BD Address: 00:80:C8:35:19:C8 ACL MTU: 192:8  SCO MTU: 64:8
        UP RUNNING PSCAN ISCAN 
        RX bytes:8308 acl:0 sco:0 events:450 errors:0
        TX bytes:2202 acl:0 sco:0 commands:338 errors:0
        Features: 0xff 0xff 0x0f 0x00 0x00 0x00 0x00 0x00
        Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
        Link policy: HOLD SNIFF PARK 
        Link mode: SLAVE ACCEPT 
        Name: 'OKN-32-G838'
        Class: 0x000100
        Service Classes: Unspecified
        Device Class: Computer, Uncategorized
        HCI Ver: 1.1 (0x1) HCI Rev: 0x1bb LMP Ver: 1.1 (0x1) LMP Subver: 0x1bb
        Manufacturer: Cambridge Silicon Radio (10)

-albert

On Fri, 13 Aug 2004 18:58:37 +0200, Marcel Holtmann <marcel@holtmann.org> wrote:
> Hi Albert,
> 
> 
> 
> > While experimenting with a hp ipaq running a 2.4.19 kernel, I noticed
> > that during a since device inquiry, multiple EVT_INQUIRY_RESULT events
> > could be generated from the same remote device.  The inquiry was done
> > using a raw hci socket.  On x86 PCs running the same userland code but
> > with more recent versions of bluez and the linux kernel, the duplicate
> > events are no longer generated.  Instead, during a single inquiry, a
> > response will be received from a remote device at most once.
> >
> > I'm assuming that sometime in the recent past, kernel level caching
> > was implemented to prevent these duplicate inquiry results from
> > propagating up to user land.  Is there a way to turn this off, so that
> > all inquiry results are passed through?
> 
> this is device specific and can be controlled by a HCI command. Show us
> the outputs of "hciconfig -a" for both devices.
> 
> Regards
> 
> Marcel
> 
>

Re: Re: [Bluez-devel] want duplicate inquiry results during a single device inquiry

[Marcel Holtmann]

Hi Albert,

> on the HP iPAQ h5550:
> # hciconfig -a
> hci0:   Type: UART
>         BD Address: 08:00:17:1B:0A:21 ACL MTU: 339:4  SCO MTU: 60:9
>         UP RUNNING PSCAN ISCAN
>         RX bytes:84 acl:0 sco:0 events:10 errors:1
>         TX bytes:298 acl:0 sco:0 commands:10 errors:0
>         Features: 0x00 0x00 0x00 0x00
>         Packet type: DM1 DH1 HV1
>         Link policy: HOLD SNIFF PARK
>         Link mode: SLAVE ACCEPT
>         Name: 'familiar (0)'
>         Class: 0x120112
>         Service Classes: Networking, Object Transfer
>         Device Class: Computer, Handheld
>         HCI Ver: 1.1 (0x1) HCI Rev: 0x180 LMP Ver: 1.1 (0x1) LMP Subver: 0x180
>         Manufacturer: RTX Telecom A/S (21)
> 
> on the desktop (d-link DBT-120):
> # hciconfig -a
> hci0:   Type: USB
>         BD Address: 00:80:C8:35:19:C8 ACL MTU: 192:8  SCO MTU: 64:8
>         UP RUNNING PSCAN ISCAN 
>         RX bytes:8308 acl:0 sco:0 events:450 errors:0
>         TX bytes:2202 acl:0 sco:0 commands:338 errors:0
>         Features: 0xff 0xff 0x0f 0x00 0x00 0x00 0x00 0x00
>         Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
>         Link policy: HOLD SNIFF PARK 
>         Link mode: SLAVE ACCEPT 
>         Name: 'OKN-32-G838'
>         Class: 0x000100
>         Service Classes: Unspecified
>         Device Class: Computer, Uncategorized
>         HCI Ver: 1.1 (0x1) HCI Rev: 0x1bb LMP Ver: 1.1 (0x1) LMP Subver: 0x1bb
>         Manufacturer: Cambridge Silicon Radio (10)

simple answer. RTX send every inquiry response up to the HCI layer and
CSR does not.

Regards

Marcel




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