linux-kernel - Re: [PATCH v5 1/4] of: also handle dma-noncoherent in of_dma_is

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Message-ID: <CAL_JsqJEPL1Jc8k5W4P8hgGzOXxgfqNKNqYuc0nLkCnV274TxA@mail.gmail.com>
Date:   Thu, 30 Jun 2022 08:57:55 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        wefu@...hat.com, Guo Ren <guoren@...nel.org>, cmuellner@...ux.com,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        Christoph Hellwig <hch@....de>,
        Samuel Holland <samuel@...lland.org>,
        Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>,
        Nick Kossifidis <mick@....forth.gr>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        devicetree@...r.kernel.org, Drew Fustini <drew@...gleboard.org>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v5 1/4] of: also handle dma-noncoherent in of_dma_is_coherent()

On Wed, Jun 29, 2022 at 4:00 PM Heiko Stuebner <heiko@...ech.de> wrote:
>
> of_dma_is_coherent() currently expects the architecture to be
> non-coherent and some devices being coherent getting marked
> as such with the dma-coherent devicetree property.
>
> For PowerPC CONFIG_OF_DMA_DEFAULT_COHERENT was added which currently
> makes of_dma_is_coherent() always return true but doesn't handle
> the case of the architecture being coherent but some devices not.
>
> So modify the function to also check for dma-noncoherent and
> set a suitable default return value. If CONFIG_OF_DMA_DEFAULT_COHERENT
> is set the value starts with true and finding dma-noncoherent will
> set it to false and without CONFIG_OF_DMA_DEFAULT_COHERENT, the
> behaviour is reversed.
>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
>  drivers/of/address.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)

Reviewed-by: Rob Herring <robh@...nel.org>