linux/drivers/dma/apple-admac.c
Martin Povišer d53171d1d0 dmaengine: apple-admac: Allocate cache SRAM to channels
[ Upstream commit 568aa6dd64 ]

There's a previously unknown part of the controller interface: We have
to assign SRAM carveouts to channels to store their in-flight samples
in. So, obtain the size of the SRAM from a read-only register and divide
it into 2K blocks for allocation to channels. The FIFO depths we
configure will always fit into 2K.

(This fixes audio artifacts during simultaneous playback/capture on
multiple channels -- which looking back is fully accounted for by having
had the caches in the DMA controller overlap in memory.)

Fixes: b127315d9a ("dmaengine: apple-admac: Add Apple ADMAC driver")
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20221019132324.8585-2-povik+lin@cutebit.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:32:46 +01:00

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