From: David Miller <davem@davemloft.net>
To: hancockrwd@gmail.com
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
romieu@fr.zoreil.com
Subject: Re: [PATCH 2.6.34] r8169: enable 64-bit DMA by default for PCI Express devices (v2)
Date: Fri, 19 Feb 2010 17:10:25 -0800 (PST) [thread overview]
Message-ID: <20100219.171025.09226171.davem@davemloft.net> (raw)
In-Reply-To: <4B7F343E.4040409@gmail.com>
From: Robert Hancock <hancockrwd@gmail.com>
Date: Fri, 19 Feb 2010 19:00:46 -0600
> Currently use of 64-bit DMA is disabled in r8169 unless the user passes the
> use_dac module option. This is reasonable for conventional PCI devices where
> broken chipsets may not handle dual-address-cycle transfers properly for
> 32-bit slots and so this may not be safe. However, PCI Express should not have
> this problem and not using 64-bit DMA results in DMA transfers needlessly using
> the IOMMU or SWIOTLB. Set the use_dac module parameter to a new default value of
> -1 which results in 64-bit DMA being enabled by default for PCI Express devices
> only.
>
> Signed-off-by: Robert Hancock <hancockrwd@gmail.com>
Applied, thanks Robert.
prev parent reply other threads:[~2010-02-20 1:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-18 3:06 [PATCH 2.6.34] r8169: enable 64-bit DMA by default for PCI Express devices Robert Hancock
2010-02-19 21:17 ` David Miller
2010-02-20 1:00 ` [PATCH 2.6.34] r8169: enable 64-bit DMA by default for PCI Express devices (v2) Robert Hancock
2010-02-20 1:10 ` David Miller [this message]
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