Hi Amit,
On Wed, Jun 6, 2018 at 9:22 AM, Amit K Bag <amit.k.bag@xxxxxxxxx> wrote:
> From: Chethan T N <chethan.tumkur.narayan@xxxxxxxxx>
>
> Observed race condition during controller recovery mechanism
> resulting the controller not responding to the reset command.
>
> To avoid such race condition need a delay of 2ms soon after the
> USB re-enumeration and before sending the Reset command which shall
> allow controller to completely recover and process the Reset command.
>
> BUG=b:64035404
> TEST=Magic tethering, P0 and P1 santiy test cases, kernel-boot log
>
> Signed-off-by: Chethan T N <chethan.tumkur.narayan@xxxxxxxxx>
> Signed-off-by: Amit K Bag <amit.k.bag@xxxxxxxxx>
> ---
> drivers/bluetooth/btusb.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index f73a27ea28cc..2303ac037240 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -1743,6 +1743,15 @@ static int btusb_setup_intel(struct hci_dev *hdev)
>
> BT_DBG("%s", hdev->name);
>
> + /* Observed race condition during controller recovery mechanism
> + * resulting the controller not responding to the reset command.
> + *
> + * To avoid such race condition need a delay of 2ms soon after the
> + * USB re-enumeration and before sending the Reset command which shall
> + * allow controller to completely recover and process the Reset command.
> + */
> + mdelay(5);
Looks like the commit message and comment are not longer in sync with
the actual value here. Also perhaps this could be a parameter so any
hardware that has this problem just set how much delay it needs before
setup can be called.
> /* The controller has a bug with the first HCI command sent to it
> * returning number of completed commands as zero. This would stall the
> * command processing in the Bluetooth core.
> --
> 2.7.4
>
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--
Luiz Augusto von Dentz
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