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Date:   Tue, 26 Feb 2019 11:05:36 +0100
From:   Joerg Roedel <joro@8bytes.org>
To:     Stanislaw Gruszka <sgruszka@redhat.com>
Cc:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        Rosen Penev <rosenp@gmail.com>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Samuel Sieb <samuel@sieb.net>,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system
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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.

Regards,

	Joerg