diff options
Diffstat (limited to 'arch/arm/plat-omap/dma.c')
| -rw-r--r-- | arch/arm/plat-omap/dma.c | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c index ecdb3da0dea9..987e6101267d 100644 --- a/arch/arm/plat-omap/dma.c +++ b/arch/arm/plat-omap/dma.c @@ -41,6 +41,15 @@ #include <plat/tc.h> +/* + * MAX_LOGICAL_DMA_CH_COUNT: the maximum number of logical DMA + * channels that an instance of the SDMA IP block can support. Used + * to size arrays. (The actual maximum on a particular SoC may be less + * than this -- for example, OMAP1 SDMA instances only support 17 logical + * DMA channels.) + */ +#define MAX_LOGICAL_DMA_CH_COUNT 32 + #undef DEBUG #ifndef CONFIG_ARCH_OMAP1 @@ -883,7 +892,7 @@ void omap_start_dma(int lch) if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) { int next_lch, cur_lch; - char dma_chan_link_map[dma_lch_count]; + char dma_chan_link_map[MAX_LOGICAL_DMA_CH_COUNT]; dma_chan_link_map[lch] = 1; /* Set the link register of the first channel */ @@ -916,6 +925,13 @@ void omap_start_dma(int lch) l |= OMAP_DMA_CCR_BUFFERING_DISABLE; l |= OMAP_DMA_CCR_EN; + /* + * As dma_write() uses IO accessors which are weakly ordered, there + * is no guarantee that data in coherent DMA memory will be visible + * to the DMA device. Add a memory barrier here to ensure that any + * such data is visible prior to enabling DMA. + */ + mb(); p->dma_write(l, CCR, lch); dma_chan[lch].flags |= OMAP_DMA_ACTIVE; @@ -965,9 +981,16 @@ void omap_stop_dma(int lch) p->dma_write(l, CCR, lch); } + /* + * Ensure that data transferred by DMA is visible to any access + * after DMA has been disabled. This is important for coherent + * DMA regions. + */ + mb(); + if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) { int next_lch, cur_lch = lch; - char dma_chan_link_map[dma_lch_count]; + char dma_chan_link_map[MAX_LOGICAL_DMA_CH_COUNT]; memset(dma_chan_link_map, 0, sizeof(dma_chan_link_map)); do { |