Re: MT76x2U crashes XHCI driver on AMD Ryzen system

From: Joerg Roedel
Date: Tue Feb 26 2019 - 05:05:41 EST

On Mon, Feb 18, 2019 at 03:37:48PM +0100, Stanislaw Gruszka wrote:
> 0001-mt76x02u-use-usb_bulk_msg-to-upload-firmware.patch
> 0002-mt76usb-do-not-use-compound-head-page-for-SG-I-O.patch
> Or problem can be solved by just one of it (either first or second).
> Additionally I'm not 100% sure if
> 0002-mt76usb-do-not-use-compound-head-page-for-SG-I-O.patch
> is correct. So perhaps some IOMMU maintainer could look at it.

The patch looks good, but I don't understand why it is needed. The AMD
IOMMU driver should handle sg->offset > PAGE_SIZE just fine. Can you
verify that this is the problem? I will look into that again if it turns
out there is bug in the IOMMU driver.