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From: Thomas Hellstrom <thellstrom@vmware.com>
To: Jerome Glisse <jglisse@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>
Subject: Use of pci_map_page in nouveau, radeon TTM.
Date: Tue, 01 Oct 2013 12:16:16 +0200	[thread overview]
Message-ID: <524AA0F0.6000000@vmware.com> (raw)

Jerome, Konrad

Forgive an ignorant question, but it appears like both Nouveau and 
Radeon may use pci_map_page() when populating TTMs on
pages obtained using the ordinary (not DMA pool). These pages will, if I 
understand things correctly, not be pages allocated with
DMA_ALLOC_COHERENT.

 From what I understand, at least for the corresponding dma_map_page() 
it's illegal for the CPU to access these pages without calling
dma_sync_xx_for_cpu(). And before the device is allowed to access them 
again, you need to call dma_sync_xx_for_device().
So mapping for PCI really invalidates the TTM interleaved CPU / device 
access model.

Or did I miss something here?

Thanks,
Thomas

             reply	other threads:[~2013-10-01 10:16 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-01 10:16 Thomas Hellstrom [this message]
2013-10-01 10:34 ` Use of pci_map_page in nouveau, radeon TTM Lucas Stach
2013-10-01 11:13   ` Thomas Hellstrom
2013-10-01 11:56     ` Lucas Stach
2013-10-01 14:14 ` Konrad Rzeszutek Wilk
2013-10-03 16:19   ` Alex Ivanov

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