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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Rob Herring <robh@kernel.org>
Cc:     robh+dt@kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, hch@lst.de, ulf.hansson@linaro.org,
        chzigotzky@xenosoft.de, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc
In-Reply-To: <20200128142646.GA17341@bogus>
References: <20200126115247.13402-1-mpe@ellerman.id.au> <20200128142646.GA17341@bogus>
Date:   Fri, 31 Jan 2020 21:40:17 +1100
Message-ID: <87k157gb8u.fsf@mpe.ellerman.id.au>
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Sender: linux-kernel-owner@vger.kernel.org
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Rob Herring <robh@kernel.org> writes:
> On Sun, 26 Jan 2020 22:52:47 +1100, Michael Ellerman wrote:
>> There's an OF helper called of_dma_is_coherent(), which checks if a
>> device has a "dma-coherent" property to see if the device is coherent
>> for DMA.
>> 
>> But on some platforms devices are coherent by default, and on some
>> platforms it's not possible to update existing device trees to add the
>> "dma-coherent" property.
>> 
>> So add a Kconfig symbol to allow arch code to tell
>> of_dma_is_coherent() that devices are coherent by default, regardless
>> of the presence of the property.
>> 
>> Select that symbol on powerpc when NOT_COHERENT_CACHE is not set, ie.
>> when the system has a coherent cache.
>> 
>> Fixes: 92ea637edea3 ("of: introduce of_dma_is_coherent() helper")
>> Cc: stable@vger.kernel.org # v3.16+
>> Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
>> Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
>> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
>> ---
>>  arch/powerpc/Kconfig | 1 +
>>  drivers/of/Kconfig   | 4 ++++
>>  drivers/of/address.c | 6 +++++-
>>  3 files changed, 10 insertions(+), 1 deletion(-)
>> 
>
> Applied, thanks.

Thanks.

cheers