Re: Questions about IOMMU & PCIe switch

From: Raimonds Cicans
Date: Wed Jan 07 2015 - 09:05:10 EST


On 07.01.2015 14:09, Clemens Ladisch wrote:
Raimonds Cicans wrote:
We have two kinds of PCIe cards:
A1 - based on chip B
A2 - based on same chip B but behind PCIe switch

Card A1 work flawlessly in any configuration,
but card A2 work flawlessly only if system
lack IOMMU or have disabled IOMMU
In theory, such a switch should be transparent.

Do we have to treat card with PCIe switch in special way?
No. But the switch has to work correctly, and driver must be
written correctly.

Which switch? Which driver?

We talk about TBS 6285 Quad DVB-T PCIe receiver card.
Starting from version V20 manufacturer added Pericom
PCIe switch PI7C9X2G304SL.

Card have 2 out of kernel drivers:
1) Semi open from TBS:
http://www.tbsdtv.com/download/document/common/tbs-linux-drivers_v141225.zip

2) Open from: https://github.com/ljalves/linux_media

If you want more information you can look at open ticket:
https://github.com/ljalves/linux_media/issues/66


Raimonds Cicans

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