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Subject: Re: [PATCH v2 1/2] arm64: dts: broadcom: clear the warnings caused by
 empty dma-ranges
To:     Arnd Bergmann <arnd@kernel.org>, Ray Jui <ray.jui@broadcom.com>
Cc:     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>,
        Bharat Gooty <bharat.gooty@broadcom.com>
References: <20201016090833.1892-1-thunder.leizhen@huawei.com>
 <20201016090833.1892-2-thunder.leizhen@huawei.com>
 <20201128045328.2411772-1-f.fainelli@gmail.com>
 <CAK8P3a1_5RgcPz+bgo1bbUBk8NTJd=1-Y5-=CsQYkFgLfTE3_A@mail.gmail.com>
 <9c6c6b7e-8c39-8c49-5c87-9b560c027841@broadcom.com>
 <CAK8P3a2XYk8D80XARrpUSBHk1yye3KHXOdaQge4HNSZZOC=xKw@mail.gmail.com>
From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <cd36cdd4-8cec-b688-9d65-3170e2943bf8@gmail.com>
Date:   Tue, 15 Dec 2020 07:40:07 -0800
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On 12/14/2020 11:46 AM, Arnd Bergmann wrote:
> On Mon, Dec 14, 2020 at 8:09 PM Ray Jui <ray.jui@broadcom.com> wrote:
>> On 11/28/2020 1:58 AM, Arnd Bergmann wrote:
>>> On Sat, Nov 28, 2020 at 5:53 AM Florian Fainelli <f.fainelli@gmail.com> wrote:
>>>>
>>>> On Fri, 16 Oct 2020 17:08:32 +0800, Zhen Lei <thunder.leizhen@huawei.com> wrote:
>>>>> The scripts/dtc/checks.c requires that the node have empty "dma-ranges"
>>>>> property must have the same "#address-cells" and "#size-cells" values as
>>>>> the parent node. Otherwise, the following warnings is reported:
>>>>>
>>>>> arch/arm64/boot/dts/broadcom/stingray/stingray-usb.dtsi:7.3-14: Warning \
>>>>> (dma_ranges_format): /usb:dma-ranges: empty "dma-ranges" property but \
>>>>> its #address-cells (1) differs from / (2)
>>>>> arch/arm64/boot/dts/broadcom/stingray/stingray-usb.dtsi:7.3-14: Warning \
>>>>> (dma_ranges_format): /usb:dma-ranges: empty "dma-ranges" property but \
>>>>> its #size-cells (1) differs from / (2)
>>>>>
>>>>> Arnd Bergmann figured out why it's necessary:
>>>>> Also note that the #address-cells=<1> means that any device under
>>>>> this bus is assumed to only support 32-bit addressing, and DMA will
>>>>> have to go through a slow swiotlb in the absence of an IOMMU.
>>>>>
>>>>> Suggested-by: Arnd Bergmann <arnd@arndb.de>
>>>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>>>>> ---
>>>>
>>>> Applied to devicetree-arm64/next, thanks!
>>>
>>> The notification may have gone missing, but I had merged it into v5.10-fixes
>>> already, and as of today, it's in mainline, so you can drop it from your
>>> next branch, or just leave it in if you want to avoid taking things out of
>>> your tree.
>>
>> It looks like this patch might have caused a regression on Stingray USB.
>> Bharat, could you please confirm?
> 
> Well, this is what I had asked about originally, I assumed that
> Florian had asked someone with access to the datasheet.

It looks like we had some bad communication here, the notification email
indicating that you had applied the patch did not make it through, and I
failed to make you aware that I was waiting for some testing from Scott
and Ray.
-- 
Florian