Re: [PATCH] Revert "dmaengine: pl330: add DMA_PAUSE feature"
From: Vinod Koul
Date: Thu May 03 2018 - 12:30:43 EST
On Sat, Apr 28, 2018 at 05:50:58PM -0400, Frank Mori Hess wrote:
> This reverts commit 88987d2c7534a0269f567fb101e6d71a08f0f01d.
>
> The pl330.c pause implementation violates the dmaengine requirement
> for no data loss, since it relies on the DMAKILL
> instruction. However, DMAKILL discards in-flight data from the
> dma controller's fifo. This is documented in the dma-330 manual
> and I have observed it with hardware doing device-to-memory burst
> transfers. The discarded data may or may not show up in the
> residue count, depending on timing (resulting in data corruption
> effectively).
Applied, thanks
--
~Vinod