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From: 'Joerg Roedel' <jroedel@suse.de>
To: "Nath, Arindam" <Arindam.Nath@amd.com>
Cc: "Deucher, Alexander" <Alexander.Deucher@amd.com>,
	'Joerg Roedel' <joro@8bytes.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Daniel Drake <drake@endlessm.com>
Subject: Re: [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS
Date: Wed, 29 Mar 2017 11:42:18 +0200	[thread overview]
Message-ID: <20170329094218.GU8329@suse.de> (raw)
In-Reply-To: <MWHPR12MB15181A0AC24BC60C4579742D9C350@MWHPR12MB1518.namprd12.prod.outlook.com>

Hi Arindam,

On Wed, Mar 29, 2017 at 07:15:42AM +0000, Nath, Arindam wrote:
> Joerg, as per my limited understanding of ATS, the ATC will respond to
> invalidation requests after making sure there are no in-flight DMA
> transactions with the address requested by IOMMU to be invalidated.
> Now since the IOMMU was sending invalidate command to GPU even though
> there was no explicit page unmapping request from the graphics
> subsystem, we _might_ end up in a situation where the ATC takes longer
> than the invalidation timeout to respond to IOMMU.

The maximum wait-time in the loop is 100ms. This should be more than
enough for the ATC to complete any in-flight transaction and flush its
internal TLB.

If that is not enough, there is almost certainly something wrong with
the hardware.



	Joerg

  reply	other threads:[~2017-03-29  9:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-28 12:16 [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS Joerg Roedel
2017-03-28 20:18 ` Deucher, Alexander
2017-03-28 20:18   ` Deucher, Alexander
2017-03-28 20:28   ` Joerg Roedel
2017-03-28 20:37     ` Deucher, Alexander
2017-03-28 20:37       ` Deucher, Alexander
2017-03-28 20:56       ` 'Joerg Roedel'
2017-03-28 21:13         ` Deucher, Alexander
2017-03-28 21:13           ` Deucher, Alexander
2017-03-28 22:26           ` 'Joerg Roedel'
2017-03-29  7:15             ` Nath, Arindam
2017-03-29  7:15               ` Nath, Arindam
2017-03-29  9:42               ` 'Joerg Roedel' [this message]
2017-03-29  9:47                 ` Nath, Arindam
2017-03-29  9:47                   ` Nath, Arindam
2017-03-29 16:21             ` Deucher, Alexander
2017-03-29 16:21               ` Deucher, Alexander
2017-04-04 16:43 ` Bjorn Helgaas
2017-04-07 12:34   ` Joerg Roedel

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