hexagon: fix IM2COL patch-embed DMA ring overflow (#30189)
* hexagon: fix IM2COL patch-embed DMA ring overflow
The exact-tiling (stride == kernel, no pad/dilation) IM2COL DMA kernel
issues IC*KH DDR->VTCM descriptors per output row without checking the
return value of dma_queue_push(), and then pops IC*KH times. The per-thread
DMA ring holds 256 entries and a push into a full ring returns false
and drops the transfer, so for IC*KH > 255 the remaining rows of the
VTCM staging buffer were never written and stale data (often NaN/inf)
leaked into the output.
Solution is to retire the oldest descriptor when the ring is full, just as the blocked
kernel in the same file already does, and wait with dma_queue_flush().
For testing, added exact-tiling test cases with IC*KH > 256 (2D 1x1, 2D 2x2 patch
embed and 1D, F16 and F32 dst), which fail on HTP without this fix.
* Apply suggestion from @max-krasnyansky
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Co-authored-by: Max Krasnyansky <maxk@qti.qualcomm.com>
