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From: Thomas Gleixner <tglx@linutronix.de>
To: David Wang <davidwang@zhaoxin.com>
Cc: 'Christoph Hellwig' <hch@infradead.org>,
	mingo@redhat.com, hpa@zytor.com, gregkh@linuxfoundation.org,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	brucechang@via-alliance.com, cooperyan@zhaoxin.com,
	qiyuanwang@zhaoxin.com, benjaminpan@viatech.com,
	lukelin@viacpu.com, timguo@zhaoxin.com
Subject: Re: [PATCH] x86/dma-mapping: override via_no_dac for new VIA PCI bridges
Date: Tue, 17 Apr 2018 10:54:37 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1804171052440.1694@nanos.tec.linutronix.de> (raw)
In-Reply-To: <000001d3d628$4e91a4c0$ebb4ee40$@zhaoxin.com>

On Tue, 17 Apr 2018, David Wang wrote:
> > On Mon, Apr 16, 2018 at 05:26:56PM +0800, David Wang wrote:
> > > PCI bridges integrated in new VIA chipset/SoC have no DAC issue.
> > > Enable DAC for the platforms with these chipset/SoC can improve DMA
> > > performance about 20% when DRAM size > 4GB.
> > >
> > 
> > So we get an exception to an exception?  Is there any way to figure out
> the
> > PCI IDs actually affected?
> Yes.
> 
> Do you mean we should list the PCI IDs of the PCI bridges which have no DAC
> issue?

The question was rather to have a list of PCI IDs for those chipsets which
have the problem and set the 'disable' flag only for those. That makes a lot
more sense than making a list of new chips which disable the disable flag.

Thanks,

	tglx

  reply	other threads:[~2018-04-17  8:54 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  8:44 [PATCH] x86/dma-mapping: override via_no_dac for new VIA PCI bridges David Wang
2018-04-17  8:54 ` Thomas Gleixner [this message]
2018-04-17 13:00   ` 'Christoph Hellwig'
2018-04-17 13:33     ` Thomas Gleixner
  -- strict thread matches above, loose matches on Subject: below --
2018-04-16  9:26 David Wang
2018-04-16 12:33 ` Christoph Hellwig

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