2013-01-21 21:04:57

by Ajay

[permalink] [raw]
Subject: Simultaneous data transfer on ACL and BLE links

Hi ,
Kernel has set some restrictions in simultaneous L2cap data
transfer on BLE and ACL links on a common device .

My test scenario is as follows
Device A has both LE and ACL link with device B and C
respectively . when i start sending l2cap data on ACL link (A to B),
it work fine . But when i starts sending BLE data along with ACL data
(A to C ) , it fails with error "send failed : interrupt system call"
. when i count the LE packets that had reached upto hci layer , it
shows some 367 packets.
Later i noticed that LE data is getting queued at hci
layer and it is not scheduled properly . following piece of code
tells us the order of scheduling.. (hci_core.c)


static void hci_tx_task(unsigned long arg)
{
struct hci_dev *hdev = (struct hci_dev *) arg;
struct sk_buff *skb;

read_lock(&hci_task_lock);

BT_DBG("%s acl %d sco %d le %d", hdev->name, hdev->acl_cnt,
hdev->sco_cnt, hdev->le_cnt);

/* Schedule queues and send stuff to HCI driver */

hci_sched_acl(hdev);

hci_sched_sco(hdev);

hci_sched_esco(hdev);

hci_sched_le(hdev);

......


Here both acl and le scheduling are using same count as
reference (hdev->acl_cnt) and they have never make use of hdev->le_cnt.

please kindly go through this issue.








--
Thanks & Regards

AJAY KV
GlobalEdge software Ltd
8892753703


Attachments:
ajay_kv.vcf (74.00 B)