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From: Arnd Bergmann <arnd@kernel.org>
To: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Cc: devicetree <devicetree@vger.kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Scott Branden <sbranden@broadcom.com>,
	Ray Jui <rjui@broadcom.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Andy Gross <agross@kernel.org>,
	bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 1/2] arm64: dts: broadcom: clear the warnings caused by empty dma-ranges
Date: Fri, 23 Oct 2020 09:17:37 +0200	[thread overview]
Message-ID: <CAK8P3a335TT1+bdHqB=FetPanXXfGv3dC7ZCkx+w+F3j00kj5A@mail.gmail.com> (raw)
In-Reply-To: <d42745b7-ef76-e584-0da2-751ac8c1cf3a@huawei.com>

On Sun, Oct 18, 2020 at 4:10 AM Leizhen (ThunderTown)
<thunder.leizhen@huawei.com> wrote:
> On 2020/10/17 3:27, Florian Fainelli wrote:
> > On 10/16/20 11:23 AM, Arnd Bergmann wrote:
> >> On Fri, Oct 16, 2020 at 6:48 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
> >>> On 10/16/20 4:01 AM, Arnd Bergmann wrote:
> >>>> On Fri, Oct 16, 2020 at 11:09 AM Zhen Lei <thunder.leizhen@huawei.com> wrote:
> >>>>>
> >>>>> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> >>>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> >>>>
> >>>> Acked-by: Arnd Bergmann <arnd@arndb.de>
> >>>>
> >>>> I see that at least the 'bcd' and 'xhci' devices in fact try to
> >>>> use 64-bit DMA. It would be good to test this on actual
> >>>> hardware to ensure that it works correctly when this is enabled.
> >>>>
> >>>> Ideally avoiding the swiotlb bounce buffering should only
> >>>> make it faster here, but there are many chips on which
> >>>> 64-bit DMA is broken in some form.
> >>>
> >>> Is this change really an improvement though? This 'usb' pseudo bus node
> >>> could just keep being defined with #address-cells = <1> and #size-cells
> >>> = <1> so as to satisfy the 'reg' definition however we could just adjust
> >>> dma-ranges to indicate full 64-bit addressing capability. Would not that
> >>> work?
> >>
> >> When #address-cells is '1', you cannot specify dma-ranges that
> >> go beyond a 32-bit address range.
> >
> > Would not it be enough to remove the 'dma-ranges' property though? Sorry
> > for being slow here.
>
> Remove the 'dma-ranges' property should also work. After all, it is equivalent
> to the original empty dma-ranges scheme. In addition, since the IOMMU nodes are
> defined, it should be enabled.

Are you sure? I was expecting the IOMMU not to get used here since
the devices do contain list an 'iommus' property.

      Arnd

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  reply	other threads:[~2020-10-23  7:19 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-16  9:08 [PATCH v2 0/2] eliminate two common errors reported by any yaml on arm64 Zhen Lei
2020-10-16  9:08 ` Zhen Lei
2020-10-16  9:08 ` [PATCH v2 1/2] arm64: dts: broadcom: clear the warnings caused by empty dma-ranges Zhen Lei
2020-10-16  9:08   ` Zhen Lei
     [not found]   ` <CAK8P3a2TSmsNSi-XFpT6AQ3jvVxJ1AW7Uf5tAo477wtwXZwUzg@mail.gmail.com>
2020-10-16 16:48     ` Florian Fainelli
2020-10-16 16:48       ` Florian Fainelli
     [not found]       ` <CAK8P3a13ywHh7igdfDSPQz9Bw8YAnKWFLKARkk2NL5u6=6yb=w@mail.gmail.com>
2020-10-16 19:27         ` Florian Fainelli
2020-10-16 19:27           ` Florian Fainelli
2020-10-18  2:10           ` Leizhen (ThunderTown)
2020-10-18  2:10             ` Leizhen (ThunderTown)
2020-10-23  7:17             ` Arnd Bergmann [this message]
2020-10-26  2:21               ` Leizhen (ThunderTown)
2020-10-26  2:21                 ` Leizhen (ThunderTown)
2020-11-09  6:18                 ` Leizhen (ThunderTown)
2020-11-09  6:18                   ` Leizhen (ThunderTown)
2020-11-09 17:28                   ` Florian Fainelli
2020-11-09 17:28                     ` Florian Fainelli
2020-11-09 17:56                     ` Arnd Bergmann
2020-11-09 17:56                       ` Arnd Bergmann
2020-11-09 18:00                       ` Florian Fainelli
2020-11-09 18:00                         ` Florian Fainelli
2020-11-28  4:53   ` Florian Fainelli
2020-11-28  4:53     ` Florian Fainelli
2020-11-28  9:58     ` Arnd Bergmann
2020-11-28  9:58       ` Arnd Bergmann
2020-12-14 19:09       ` Ray Jui
2020-12-14 19:09         ` Ray Jui
2020-12-14 19:46         ` Arnd Bergmann
2020-12-14 19:46           ` Arnd Bergmann
2020-12-15 15:40           ` Florian Fainelli
2020-12-15 15:40             ` Florian Fainelli
     [not found]           ` <CACvutz9v+TBUbrCo3X-u5ebbs04nR0y0yQN3qWfSAyZVy9RM2g@mail.gmail.com>
2020-12-15 15:41             ` Florian Fainelli
2020-12-15 15:41               ` Florian Fainelli
2020-12-15 15:49               ` Arnd Bergmann
2020-12-15 15:49                 ` Arnd Bergmann
2021-01-12 18:28                 ` Ray Jui
2021-01-12 18:28                   ` Ray Jui
2021-01-12 20:40                   ` Arnd Bergmann
2021-01-12 20:40                     ` Arnd Bergmann
2021-01-12 20:57                     ` Ray Jui
2021-01-12 20:57                       ` Ray Jui
2021-01-13  3:42                       ` Bharat Gooty
2021-01-13  3:42                         ` Bharat Gooty
2021-01-13  8:05                         ` Arnd Bergmann
2021-01-13  8:05                           ` Arnd Bergmann
2021-01-13 16:55                           ` Florian Fainelli
2021-01-13 16:55                             ` Florian Fainelli
2021-01-13 17:45                             ` Ray Jui
2021-01-13 17:45                               ` Ray Jui
2020-10-16  9:08 ` [PATCH v2 2/2] arm64: dts: qcom: " Zhen Lei
2020-10-16  9:08   ` Zhen Lei
2020-11-11  4:44   ` Bjorn Andersson
2020-11-11  4:44     ` Bjorn Andersson
2020-12-29 20:15 ` [PATCH v2 0/2] eliminate two common errors reported by any yaml on arm64 patchwork-bot+linux-arm-msm

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