linux-kernel - Re: [PATCH 4/9] arm64: dma-mapping: export symbol arch_setup_dma

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Message-ID: <a8fa87e4-4d70-eb60-f1c5-94071d6394aa@arm.com>
Date:   Thu, 12 Oct 2017 18:06:48 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Jim Quinlan <jim2101024@...il.com>, linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>, linux-mips@...ux-mips.org,
        Florian Fainelli <f.fainelli@...il.com>,
        devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        Kevin Cernekee <cernekee@...il.com>,
        Will Deacon <will.deacon@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Rob Herring <robh+dt@...nel.org>,
        bcm-kernel-feedback-list@...adcom.com,
        Gregory Fong <gregory.0xf0@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Brian Norris <computersforpeace@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 4/9] arm64: dma-mapping: export symbol arch_setup_dma_ops

On 11/10/17 23:34, Jim Quinlan wrote:
> The BrcmSTB driver needs to get ahold of a pointer to swiotlb_dma_ops.
> However, that variable is defined as static.  Instead, we use
> arch_setup_dma_ops() to get the pointer to swiotlb_dma_ops.  Since
> we also want our driver to be a separate module, we need to
> export this function.

NAK. Retrieve the platform-assigned ops from the device via
get_dma_ops() and stash them in your drvdata or wherever before you
replace them. Don't go poking around arch code internals directly from a
driver.

Robin.

> Signed-off-by: Jim Quinlan <jim2101024@...il.com>
> ---
>  arch/arm64/mm/dma-mapping.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 614af88..dae572f 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -936,3 +936,4 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>  	}
>  #endif
>  }
> +EXPORT_SYMBOL(arch_setup_dma_ops);
>