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- From d70a417420f9d10e86031ec24da68b71668aa833 Mon Sep 17 00:00:00 2001
- From: Phil Elwell <[email protected]>
- 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 <[email protected]>
- ---
- 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
- @@ -141,6 +141,10 @@ 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 */
- @@ -454,7 +458,8 @@ 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)
- @@ -481,7 +486,8 @@ 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;
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