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Re: [PATCH] nand: ranw: qcom_nand: stop using phys_to_dma()

On Wed, Jul 11, 2018 at 3:04 PM, Boris Brezillon
<boris.brezillon@xxxxxxxxxxx> wrote:
> On Wed, 11 Jul 2018 14:26:58 +0200
> Arnd Bergmann <arnd@xxxxxxxx> wrote:
>> Compile-testing this driver on x86 caused a link error:
>> ERROR: "__phys_to_dma" [drivers/mtd/nand/raw/qcom_nandc.ko] undefined!
>> The problem here is that the driver attempts to convert the physical
>> address into the DMA controller as a dma_addr_t and calls phys_to_dma()
>> to do the conversion.
>> However, there is no generic way to convert a phys_addr_t into a dma_addr_t
>> for anything other than RAM (which should use the dma-mapping API instead).
>> The only correct use of phys_to_dma() instead is inside of the dma-mapping
>> implementation.
> Should we use dma_map_resource() to do the phys_addr_t to dma_addr_t
> conversion?

I had not seen that interface before, but yes, that does seem like the best
way to do it here.