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From:   dillon min <dillon.minfei@gmail.com>
Date:   Tue, 9 Jun 2020 23:58:32 +0800
Message-ID: <CAL9mu0KWq-ANkLBRv_49kGzWf_kDPjMvMeA7S4E6f5MpVtjKaw@mail.gmail.com>
Subject: Re: [PATCH 1/2] ARM: dts: stm32: Setup 4M bytes reserved memory for mmap
To:     Rob Herring <robh+dt@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        linux@armlinux.org.uk, Vladimir Murzin <vladimir.murzin@arm.com>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        allison@lohutok.net, info@metux.net, tglx@linutronix.de, hch@lst.de
Cc:     "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi Christoph Hellwig,

This is the patchset. for your reference.

thanks,

On Mon, Jun 8, 2020 at 4:30 PM <dillon.minfei@gmail.com> wrote:
>
> From: dillon min <dillon.minfei@gmail.com>
>
> To mmap a framebuffer or v4l2 buffer from kernel to userspace on
> no-mmu platform, we need rely on 'arm_nommu_dma_ops' from
> arch/arm/mm/dma-mapping-nommu.c , so setup 4M bytes memory
> reserved for this purpose.
>
> Signed-off-by: dillon min <dillon.minfei@gmail.com>
> ---
>  arch/arm/boot/dts/stm32f469-disco.dts | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/arch/arm/boot/dts/stm32f469-disco.dts b/arch/arm/boot/dts/stm32f469-disco.dts
> index 9397db0c43de..082b24ee81f7 100644
> --- a/arch/arm/boot/dts/stm32f469-disco.dts
> +++ b/arch/arm/boot/dts/stm32f469-disco.dts
> @@ -65,6 +65,20 @@
>                 reg = <0x00000000 0x1000000>;
>         };
>
> +       reserved-memory {
> +               #address-cells = <1>;
> +               #size-cells = <1>;
> +               ranges;
> +
> +               linux,dma {
> +                       compatible = "shared-dma-pool";
> +                       size = <0x400000>;
> +                       no-map;
> +                       linux,dma-default;
> +               };
> +
> +       };
> +
>         aliases {
>                 serial0 = &usart3;
>         };
> --
> 2.7.4
>