[Intel-gfx] [PATCH] drm/i915: permit zero valued dmap in for_each_sgt_dma

[Chris Wilson]

Quoting Matthew Auld (2019-01-30 19:18:25)
> Break on NULL iter.sgp, rather than dmap == 0, on the off chance that we
> have some hypothetical selftest or similar in the future that considers
> dmap = 0 to be perfectly valid.

0 == DMA_MAPPING_ERROR

It wouldn't be a dma iterator at that point.

for_each_sgt_device_addr, _daddr?
-Chris