Message-ID: <4D296B12.8000801@openwrt.org>
Date: Sun, 09 Jan 2011 09:00:18 +0100
From: Gabor Juhos <juhosg@openwrt.org>
MIME-Version: 1.0
To: greearb@candelatech.com
CC: linux-wireless@vger.kernel.org, ath9k-devel@venema.h4ckr.net
Subject: Re: [PATCH] ath9k:  Implement rx copy-break.
References: <1294500800-29191-1-git-send-email-greearb@candelatech.com>
In-Reply-To: <1294500800-29191-1-git-send-email-greearb@candelatech.com>
Content-Type: text/plain; charset=ISO-8859-2
Sender: linux-wireless-owner@vger.kernel.org

Hi Ben,

> From: Ben Greear <greearb@candelatech.com>
> 
> This saves us constantly allocating large, multi-page
> skbs.  It should fix the order-1 allocation errors reported,
> and in a 60-vif scenario, this significantly decreases CPU
> utilization, and latency, and increases bandwidth.
> 
> Signed-off-by: Ben Greear <greearb@candelatech.com>
> ---
> :100644 100644 b2497b8... ea2f67c... M	drivers/net/wireless/ath/ath9k/recv.c
>  drivers/net/wireless/ath/ath9k/recv.c |   92 ++++++++++++++++++++++-----------
>  1 files changed, 61 insertions(+), 31 deletions(-)

<...>

> +		if (use_copybreak) {
> +			struct pci_dev *pdev = to_pci_dev(sc->dev);

This would cause undefined behaviour with ath9k devices sitting on an AHB bus.

> +			pci_dma_sync_single_for_cpu(pdev, bf->bf_buf_addr,
> +						    len, PCI_DMA_FROMDEVICE);
> +			skb_copy_from_linear_data(bf->bf_mpdu, skb->data, len);
> +			pci_dma_sync_single_for_device(pdev, bf->bf_buf_addr,
> +						       len, PCI_DMA_FROMDEVICE);

Please use the bus agnostic equivalents of these DMA functions.

- Gabor