pci-usb/pci-sata broken with LPAE config after "reduce use of block bounce buffers"

Kishon Vijay Abraham I <kishon@xxxxxx> · Fri, 15 Nov 2019 16:29:31 +0530

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.

The first commit where we actually start seeing issue is
commit 21e07dba9fb1179148089d611fc9e6e70d1887c3 (j7_serdes_v2)
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Tue Apr 3 19:09:59 2018 +0200

    scsi: reduce use of block bounce buffers

Can you give hints on how to solve this?

Thanks
Kishon