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Date:   Fri, 15 Nov 2019 14:06:54 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Kishon Vijay Abraham I <kishon@ti.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: pci-usb/pci-sata broken with LPAE config after "reduce use of
 block bounce buffers"
Message-ID: <20191115130654.GA3414@lst.de>
References: <120f7c3e-363d-deb0-a347-782ac869ee0d@ti.com>
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On Fri, Nov 15, 2019 at 04:29:31PM +0530, Kishon Vijay Abraham I wrote:
> Hi Christoph,
> 
> I think we are encountering a case where the connected PCIe card (like PCIe USB
> card) supports 64-bit addressing and the ARM core supports 64-bit addressing
> but the PCIe controller in the SoC to which PCIe card is connected supports
> only 32-bits.
> 
> Here dma APIs can provide an address above the 32 bit region to the PCIe card.
> However this will fail when the card tries to access the provided address via
> the PCIe controller.

What kernel version did you see your problems with?

Linux 5.3 added swiotlb to arm LPAE configs for exactly that case.