Re: [PATCH v2 1/3] dma-mapping: introduce new dma unmap and sync api variants

[hch@xxxxxx]

On Thu, Oct 24, 2019 at 12:41:41PM +0000, Laurentiu Tudor wrote:
> From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
> 
> Introduce a few new dma unmap and sync variants that, on top of the
> original variants, return the virtual address corresponding to the
> input dma address.
> In order to implement this a new dma map op is added and used:
>     void *get_virt_addr(dev, dma_handle);
> It does the actual conversion of an input dma address to the output
> virtual address.

We'll definitively need an implementation for dma-direct at least as
well.  Also as said previously we need a dma_can_unmap_by_dma_addr()
or similar helper that tells the driver beforehand if this works, so
that the driver can either use a sub-optimal workaround or fail the
probe if this functionality isn't implemented.