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Date: Tue, 07 Oct 2014 14:30:41 +0530
From: Varka Bhadram <varkabhadram@gmail.com>
MIME-Version: 1.0
Subject: Re: [PATCH bluetooth-next 3/9] at86rf230: correct aret lifs and sifs
 handling
References: <1412671113-26675-1-git-send-email-alex.aring@gmail.com> <1412671113-26675-4-git-send-email-alex.aring@gmail.com> <5433A9A0.5090407@gmail.com> <20141007085629.GA27930@omega>
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To: Alexander Aring <alex.aring@gmail.com>
Cc: linux-wpan@vger.kernel.org, m.olbrich@pengutronix.de

On 10/07/2014 02:26 PM, Alexander Aring wrote:
> On Tue, Oct 07, 2014 at 02:21:44PM +0530, Varka Bhadram wrote:
>> Hi Alex,
>>
>> On 10/07/2014 02:08 PM, Alexander Aring wrote:
>>
>>> This patch adds lifs/sifs handling only if max_frame_retries is above
>>> zero. The at86rf2xx datasheets says nothing about phy lifs/sifs
>>> handling. I asked the atmel support and they said lifs/sifs is done
>>> by phy when max_frame_retries is above zero.
>>>
>>> Signed-off-by: Alexander Aring <alex.aring@gmail.com>
>>> ---
>>>   drivers/net/ieee802154/at86rf230.c | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>>
>>> diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
>>> index 44d2f1d..2a25324 100644
>>> --- a/drivers/net/ieee802154/at86rf230.c
>>> +++ b/drivers/net/ieee802154/at86rf230.c
>>> @@ -89,6 +89,7 @@ struct at86rf230_local {
>>>   	struct at86rf230_state_change irq;
>>>   	bool tx_aret;
>>> +	s8 max_frame_retries;
>> Why s8 here..? Is there any reason..
>>
> yep.
>
>>>   	bool is_tx;
>>>   	/* spinlock for is_tx protection */
>>>   	spinlock_t lock;
>>> @@ -1001,6 +1002,9 @@ at86rf230_xmit(struct ieee802154_dev *dev, struct sk_buff *skb)
>>>   		return -ETIMEDOUT;
>>>   	}
>>> +	if (lp->max_frame_retries > 0)
>>> +		return 0;
>>> +
>>>   	/* Interfame spacing time, which is phy depend.
>>>   	 * TODO
>>>   	 * Move this handling in MAC 802.15.4 layer.
>>> @@ -1230,6 +1234,7 @@ at86rf230_set_frame_retries(struct ieee802154_dev *dev, s8 retries)
>>>   		return -EINVAL;
>>>   	lp->tx_aret = retries >= 0;
>>> +	lp->max_frame_retries = retries;
> this parameter retries is s8. The value "-1" means no ARET handling here.
>
> If you do now u8 at max_frame_retries, then we get a overflow by setting
> "-1" here and have a invalid max_frame_retries setting of 255.
>
> Then checking via:
>
> if (lp->max_frame_retries > 0)
>
> doesn't work.
>
> - Alex

Thanks..

-- 
Regards,
Varka Bhadram.