From: Eric Dumazet <eric.dumazet@gmail.com>
To: Andy Cress <andy.cress@us.kontron.com>
Cc: netdev@vger.kernel.org
Subject: RE: pch_gbe: dont-copy-payload (was [PATCH 1/4] ...)
Date: Mon, 06 Aug 2012 16:52:36 +0200 [thread overview]
Message-ID: <1344264756.26674.19.camel@edumazet-glaptop> (raw)
In-Reply-To: <40680C535D6FE6498883F1640FACD44D0122CF12@ka-exchange-1.kontronamerica.local>
On Mon, 2012-08-06 at 07:19 -0700, Andy Cress wrote:
> I found out why the proposed dont-copy-payload patch didn't work with
> this pch_gbe NIC.
> This NIC PHY requires 64-byte-aligned DMA, and the transmit buffers
> won't be transferred if skb->data is not 64-byte-aligned. Apparently
> the data copy has a by-product of aligning the buffers.
>
> I tried using skb_reserve(skb,64) in pch_gbe_alloc_tx_buffers and
> pch-gbe_alloc_rx_buffers, but that didn't seem to resolve it.
>
> How can I make sure that the transmit data buffers are
> 64-byte-aligned?
>
There is no support for such requirement in linux stacks.
Only solution for the driver is to copy all frames to 64-byte-aligned
bounce buffers.
next prev parent reply other threads:[~2012-08-06 14:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-16 20:03 [PATCH 1/4] pch_gbe: Fix the checksum fill to the error location Andy Cress
2012-07-17 0:59 ` Paul Gortmaker
2012-07-17 7:09 ` Eric Dumazet
2012-07-17 7:33 ` Eric Dumazet
2012-07-17 14:20 ` Andy Cress
2012-07-25 20:10 ` Andy Cress
2012-08-06 14:19 ` pch_gbe: dont-copy-payload (was [PATCH 1/4] ...) Andy Cress
2012-08-06 14:52 ` Eric Dumazet [this message]
2012-07-17 8:04 ` [PATCH 1/4] pch_gbe: Fix the checksum fill to the error location Zhong Hongbo
2012-07-17 8:48 ` Eric Dumazet
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