Date:   Tue, 14 Mar 2023 19:07:58 -0700 (PDT)
Subject:     Re: [PATCH v2 4/5] riscv: Select ARCH_DMA_DEFAULT_COHERENT
In-Reply-To: <Y/fmqwboOv/JhWf/@spud>
CC:     jiaxun.yang@flygoat.com, linux-mips@vger.kernel.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        tsbogend@alpha.franken.de, mpe@ellerman.id.au,
        Paul Walmsley <paul.walmsley@sifive.com>, robh+dt@kernel.org,
        Christoph Hellwig <hch@lst.de>, m.szyprowski@samsung.com,
        robin.murphy@arm.com, linux-riscv@lists.infradead.org
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     Conor Dooley <conor@kernel.org>
Message-ID: <mhng-9bf3f6be-12f9-466e-90b8-50f2d96971fe@palmer-ri-x1c9a>
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On Thu, 23 Feb 2023 14:20:27 PST (-0800), Conor Dooley wrote:
> On Thu, Feb 23, 2023 at 11:36:43AM +0000, Jiaxun Yang wrote:
>> For riscv our assumption is unless a device states it is non-coherent,
>> we take it to be DMA coherent.
>> 
>> Select ARCH_DMA_DEFAULT_COHERENT to ensure dma_default_coherent
>> is always initialized to true.
>> 
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>> ---
>>  arch/riscv/Kconfig | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 1d46a268ce16..b71ce992c0c0 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -233,6 +233,7 @@ config LOCKDEP_SUPPORT
>>  
>>  config RISCV_DMA_NONCOHERENT
>>  	bool
>> +	select ARCH_DMA_DEFAULT_COHERENT
>
> Since we are always coherent by default, I feel like you should put this
> in the main "config RISCV" section, where OF_DMA_DEFAULT_COHERENT
> currently is, no?

Seems reasonable to me.  With that

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>

as I'm assuming these should all stay together.

Thanks!

>
> Wouldn't bother respinning for that unless the dma folk have comments
> for you.
>
>>  	select ARCH_HAS_DMA_PREP_COHERENT
>>  	select ARCH_HAS_SETUP_DMA_OPS
>>  	select ARCH_HAS_SYNC_DMA_FOR_CPU
>> -- 
>> 2.37.1 (Apple Git-137.1)
>>