From 4ebec374d97c0bba1e41558071bfa062894b07a0 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Fri, 20 Jul 2018 22:03:41 +0100 Subject: [PATCH] bcm2835-dma: Add support for per-channel flags Add the ability to interpret the high bits of the dreq specifier as flags to be included in the DMA_CS register. The motivation for this change is the ability to set the DISDEBUG flag for SD card transfers to avoid corruption when using the VPU debugger. Signed-off-by: Phil Elwell --- drivers/dma/bcm2835-dma.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/dma/bcm2835-dma.c +++ b/drivers/dma/bcm2835-dma.c @@ -146,6 +146,10 @@ struct bcm2835_desc { #define BCM2835_DMA_S_DREQ BIT(10) /* enable SREQ for source */ #define BCM2835_DMA_S_IGNORE BIT(11) /* ignore source reads - read 0 */ #define BCM2835_DMA_BURST_LENGTH(x) ((x & 15) << 12) +#define BCM2835_DMA_CS_FLAGS(x) (x & (BCM2835_DMA_PRIORITY(15) | \ + BCM2835_DMA_PANIC_PRIORITY(15) | \ + BCM2835_DMA_WAIT_FOR_WRITES | \ + BCM2835_DMA_DIS_DEBUG)) #define BCM2835_DMA_PER_MAP(x) ((x & 31) << 16) /* REQ source */ #define BCM2835_DMA_WAIT(x) ((x & 31) << 21) /* add DMA-wait cycles */ #define BCM2835_DMA_NO_WIDE_BURSTS BIT(26) /* no 2 beat write bursts */ @@ -461,7 +465,8 @@ static void bcm2835_dma_start_desc(struc c->desc = d = to_bcm2835_dma_desc(&vd->tx); writel(d->cb_list[0].paddr, c->chan_base + BCM2835_DMA_ADDR); - writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS); + writel(BCM2835_DMA_ACTIVE | BCM2835_DMA_CS_FLAGS(c->dreq), + c->chan_base + BCM2835_DMA_CS); } static irqreturn_t bcm2835_dma_callback(int irq, void *data) @@ -488,7 +493,8 @@ static irqreturn_t bcm2835_dma_callback( * if this IRQ handler is threaded.) If the channel is finished, it * will remain idle despite the ACTIVE flag being set. */ - writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE, + writel(BCM2835_DMA_INT | BCM2835_DMA_ACTIVE | + BCM2835_DMA_CS_FLAGS(c->dreq), c->chan_base + BCM2835_DMA_CS); d = c->desc;