From: nicolas.ferre@atmel•com (Nicolas Ferre)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 06/10] net/macb: clean up ring buffer logic
Date: Wed, 31 Oct 2012 11:39:49 +0100 [thread overview]
Message-ID: <5090FFF5.6020109@atmel.com> (raw)
In-Reply-To: <5090F67C.9020104@atmel.com>
On 10/31/2012 10:59 AM, Nicolas Ferre :
> On 10/30/2012 07:22 PM, H?vard Skinnemoen :
>> On Tue, Oct 30, 2012 at 4:12 AM, David Laight <David.Laight@aculab•com> wrote:
>>>> Instead of masking head and tail every time we increment them, just let them
>>>> wrap through UINT_MAX and mask them when subscripting. Add simple accessor
>>>> functions to do the subscripting properly to minimize the chances of messing
>>>> this up.
>>> ...
>>>> +static unsigned int macb_tx_ring_avail(struct macb *bp)
>>>> +{
>>>> + return TX_RING_SIZE - (bp->tx_head - bp->tx_tail);
>>>> +}
>>>
>>> That one doesn't look quite right to me.
>>> Surely it should be masking with 'TX_RING_SIZE - 1'
>>
>> Why is that? head and tail can never be more than TX_RING_SIZE apart,
>> so it shouldn't make any difference.
>
> Absolutely.
Well not so absolute, after having thinking twice ;-)
We should move to:
static unsigned int macb_tx_ring_avail(struct macb *bp)
{
return (TX_RING_SIZE - (bp->tx_head - bp->tx_tail) & (TX_RING_SIZE - 1));
}
Thanks David!
(sorry for the noise) Bye,
--
Nicolas Ferre
next prev parent reply other threads:[~2012-10-31 10:39 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-30 10:17 [PATCH v3 00/10] net/macb: driver enhancement concerning GEM support, ring logic and cleanup Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 01/10] net/macb: Add support for Gigabit Ethernet mode Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 02/10] net/macb: memory barriers cleanup Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 03/10] net/macb: change debugging messages Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 04/10] net/macb: remove macb_get_drvinfo() Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 05/10] net/macb: tx status is more than 8 bits now Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 06/10] net/macb: clean up ring buffer logic Nicolas Ferre
2012-10-30 11:12 ` David Laight
2012-10-30 18:22 ` Håvard Skinnemoen
2012-10-31 8:57 ` David Laight
2012-10-31 9:59 ` Nicolas Ferre
2012-10-31 10:39 ` Nicolas Ferre [this message]
2012-10-31 9:48 ` David Laight
2012-10-30 11:30 ` [PATCH] net/at91_ether: fix the use of macb structure Nicolas Ferre
2012-11-03 19:04 ` David Miller
2012-11-04 23:02 ` Nicolas Ferre
2012-10-30 10:17 ` [PATCH v3 07/10] net/macb: ethtool interface: add register dump feature Nicolas Ferre
2012-10-30 10:18 ` [PATCH v3 08/10] net/macb: better manage tx errors Nicolas Ferre
2012-10-30 10:18 ` [PATCH v3 09/10] net/macb: Offset first RX buffer by two bytes Nicolas Ferre
2012-10-30 10:18 ` [PATCH v3 10/10] net/macb: add pinctrl consumer support Nicolas Ferre
2012-10-30 17:37 ` Joachim Eastwood
2012-10-31 10:42 ` Nicolas Ferre
2012-10-30 11:26 ` [PATCH v3 00/10] net/macb: driver enhancement concerning GEM support, ring logic and cleanup Nicolas Ferre
2012-10-30 17:31 ` Joachim Eastwood
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