From 57b772b86871e025c1fc149d8c3e48667be0869f Mon Sep 17 00:00:00 2001 From: Robin Gong Date: Wed, 20 Jun 2018 00:57:00 +0800 Subject: dmaengine: imx-sdma: add virt-dma support The legacy sdma driver has below limitations or drawbacks: 1. Hardcode the max BDs number as "PAGE_SIZE / sizeof(*)", and alloc one page size for one channel regardless of only few BDs needed most time. But in few cases, the max PAGE_SIZE maybe not enough. 2. One SDMA channel can't stop immediatley once channel disabled which means SDMA interrupt may come in after this channel terminated.There are some patches for this corner case such as commit "2746e2c389f9", but not cover non-cyclic. The common virt-dma overcomes the above limitations. It can alloc bd dynamically and free bd once this tx transfer done. No memory wasted or maximum limititation here, only depends on how many memory can be requested from kernel. For No.2, such issue can be workaround by checking if there is available descript("sdmac->desc") now once the unwanted interrupt coming. At last the common virt-dma is easier for sdma driver maintain. Signed-off-by: Robin Gong Reviewed-by: Sascha Hauer Tested-by: Lucas Stach Signed-off-by: Vinod Koul --- drivers/dma/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/dma/Kconfig') diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index ca1680afa20a..d4a4230a7942 100644 --- a/drivers/dma/Kconfig +++ b/drivers/dma/Kconfig @@ -250,6 +250,7 @@ config IMX_SDMA tristate "i.MX SDMA support" depends on ARCH_MXC select DMA_ENGINE + select DMA_VIRTUAL_CHANNELS help Support the i.MX SDMA engine. This engine is integrated into Freescale i.MX25/31/35/51/53/6 chips. -- cgit v1.2.3