On Thu, Sep 10, 2020 at 07:02:23PM +0100, Robin Murphy wrote:
> On 2020-09-10 06:40, Christoph Hellwig wrote:
>> Move the helpers to translate to and from direct mapping DMA addresses
>> to dma-direct.h. This not only is the most logical place, but the new
>> placement also avoids dependency loops with pending commits.
>
> For the straightforward move as it should be,
>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
>
> However I do wonder how much of this could be cleaned up further...
>> +
>> +#ifdef __arch_page_to_dma
>> +#error Please update to __arch_pfn_to_dma
>> +#endif
>
> This must be long, long dead by now.
Yeah. I had a patch to remove this which lead me into the rabbit
hole your described later. A few patches in I decided to give up
and just do the trivial move. But it probably makes sense to pick
up at least the two trivial dead code removal patches..
>> +static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
>> +{
>> + unsigned long pfn = __bus_to_pfn(addr);
>> +
>> + if (dev)
>> + pfn += dev->dma_pfn_offset;
>> +
>> + return pfn;
>> +}
>
> These are only overridden for OMAP1510, and it looks like it wouldn't take
> much for the platform code or ohci-omap driver to set up a generic DMA
> offset for the relevant device.
I sent a ping to the omap maintainers earlier this week to ask for that :)
>> +static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
>> +{
>> + if (dev)
>> + return pfn_to_dma(dev, virt_to_pfn(addr));
>> +
>> + return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
>> +}
>
> And this is only used for some debug prints in dmabounce.
>
> Similarly the __bus_to_*()/__*_to_bus() calls themselves only appear
> significant to mach-footbridge any more, and could probably also be evolved
> into regular DMA offsets now that all API calls must have a non-NULL
> device. I think I might come back and take a closer look at all this at
> some point in future... :)
Yes, pretty much all of this should eventually go away. I just don't
want to bock the ranges work on all kinds of random arm cleanups..
