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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Wed, 13 Jan 2021 09:05:22 +0100
Message-ID: <CAK8P3a3SdvOk=chp39-ypvHsqCJkuqFG1qn+tyJ3h71OrzgDWw@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] arm64: dts: broadcom: clear the warnings caused by
 empty dma-ranges
To:     Bharat Gooty <bharat.gooty@broadcom.com>
Cc:     Ray Jui <ray.jui@broadcom.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        devicetree <devicetree@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Scott Branden <sbranden@broadcom.com>,
        Ray Jui <rjui@broadcom.com>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
        Zhen Lei <thunder.leizhen@huawei.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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On Wed, Jan 13, 2021 at 4:42 AM Bharat Gooty <bharat.gooty@broadcom.com> wrote:
>
> Hello Ray,
>
> I had cross checked with Design and integration team.
> Yes we can set the "dma-rages" to 40 bit DMA ranges. Tested, it is working.
>
> -----Original Message-----
> From: Ray Jui <ray.jui@broadcom.com>
>
> Bharat can correct me if I'm wrong, but I don't think we have a bug in
> the USB DMA engine that causes it can only address 32-bit. I believe we
> can set dma-ranges size to 40-bit here.
>
> The dma-range property is though required to be specified, instead of
> leaving it as empty, with the use of IOMMU. That seems to be a v5.10
> specific behavior as I described below.

Ok, thanks for double-checking. I had misremembered the version
that actually went into the as the one that used 64-bit dma-ranges
and thought that was what broke, rather than the version without
dma-ranges.

If any of you want to send me that bugfix directly, or have Florian
pick it up through his fixes branch, I'll make sure we get it into v5.11.

       Arnd