Subject: Re: [Bluez-devel] [PATCH] /include/net/bluetooth/hci.h : modify
	ACL_PTYPE_MASK
From: Marcel Holtmann <marcel@holtmann.org>
To: BlueZ Mailing List <bluez-devel@lists.sourceforge.net>
In-Reply-To: <1112624867.4782.27.camel@g-xw4200-6.rd.francetelecom.fr>
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Message-Id: <1112869640.9047.60.camel@pegasus>
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Date: Thu, 07 Apr 2005 12:27:20 +0200

Hi Emmanuel,

> I've noticed that ACL_PTYPE_MASK is defined as the binary negation of
> SCO_PTYPE_MASK in /include/net/bluetooth/hci.h .
> 
> Although this happens to be not wrong currently, because none of the
> values (0x0020, 0x0040, 0x0080) used by HV1, HV2 and HV3 have a meaning
> for ACL packets, there is AFAIK no norm stating that this won't change
> (these values are just marked as "Reserved for future use" in the
> Bluetooth Specification version 2.0).
> 
> Furthermore, value 0x0001 is marked as "Reserved for future use" for
> both ACL and SCO packets. Therefore, by forbidding their use for SCO
> packets, and defining the ACL mask as the SCO mask's negation, we are
> allowing it's use for ACL packets, which could have unspecified results
> on any hardware using a future Bluetooth Specification version.
> 
> I suggest the following patch : 
> 
> 
> --- old/include/net/bluetooth/hci.h       2005-03-26 04:28:36.000000000
> +0100
> +++ new/include/net/bluetooth/hci.h      2005-04-04 16:08:24.372117996
> +0200
> @@ -124,7 +124,8 @@
>  #define HCI_HV3                0x0080
> 
>  #define SCO_PTYPE_MASK (HCI_HV1 | HCI_HV2 | HCI_HV3)
> -#define ACL_PTYPE_MASK (~SCO_PTYPE_MASK)
> +#define ACL_PTYPE_MASK (HCI_DM1 | HCI_DM3 | HCI_DM5 \
> +		| HCI_DH1 | HCI_DH3 | HCI_DH5)
> 
>  /* ACL flags */
>  #define ACL_CONT               0x01
> 
> 
> Note that this patch has the side effect of blocking any flag that is
> not defined in hci.h for ACL packets (like 0x0002 : "2-DH1 may not be
> used"), but I assume that using such a flag somewhere would just be a
> bug.

there is no good reason to include such a patch. The problem with the
newer specifications is that the packet type is different for ACL and
SCO/eSCO connections and thus they don't overlap anymore. This means
that we need two different packet types that can be set by users. And
having the option to disable EDR is a good thing. With your patch this
is no longer possible. When we finally add full eSCO support, I will
think about how we can do this better.

Regards

Marcel


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