diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/ep93xx_dma.c | 117 |
1 files changed, 93 insertions, 24 deletions
diff --git a/drivers/dma/ep93xx_dma.c b/drivers/dma/ep93xx_dma.c index f6e9b572b998..c64917ec313d 100644 --- a/drivers/dma/ep93xx_dma.c +++ b/drivers/dma/ep93xx_dma.c @@ -71,6 +71,7 @@ #define M2M_CONTROL_TM_SHIFT 13 #define M2M_CONTROL_TM_TX (1 << M2M_CONTROL_TM_SHIFT) #define M2M_CONTROL_TM_RX (2 << M2M_CONTROL_TM_SHIFT) +#define M2M_CONTROL_NFBINT BIT(21) #define M2M_CONTROL_RSS_SHIFT 22 #define M2M_CONTROL_RSS_SSPRX (1 << M2M_CONTROL_RSS_SHIFT) #define M2M_CONTROL_RSS_SSPTX (2 << M2M_CONTROL_RSS_SHIFT) @@ -79,7 +80,22 @@ #define M2M_CONTROL_PWSC_SHIFT 25 #define M2M_INTERRUPT 0x0004 -#define M2M_INTERRUPT_DONEINT BIT(1) +#define M2M_INTERRUPT_MASK 6 + +#define M2M_STATUS 0x000c +#define M2M_STATUS_CTL_SHIFT 1 +#define M2M_STATUS_CTL_IDLE (0 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_CTL_STALL (1 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_CTL_MEMRD (2 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_CTL_MEMWR (3 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_CTL_BWCWAIT (4 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_CTL_MASK (7 << M2M_STATUS_CTL_SHIFT) +#define M2M_STATUS_BUF_SHIFT 4 +#define M2M_STATUS_BUF_NO (0 << M2M_STATUS_BUF_SHIFT) +#define M2M_STATUS_BUF_ON (1 << M2M_STATUS_BUF_SHIFT) +#define M2M_STATUS_BUF_NEXT (2 << M2M_STATUS_BUF_SHIFT) +#define M2M_STATUS_BUF_MASK (3 << M2M_STATUS_BUF_SHIFT) +#define M2M_STATUS_DONE BIT(6) #define M2M_BCR0 0x0010 #define M2M_BCR1 0x0014 @@ -426,15 +442,6 @@ static int m2p_hw_interrupt(struct ep93xx_dma_chan *edmac) /* * M2M DMA implementation - * - * For the M2M transfers we don't use NFB at all. This is because it simply - * doesn't work well with memcpy transfers. When you submit both buffers it is - * extremely unlikely that you get an NFB interrupt, but it instead reports - * DONE interrupt and both buffers are already transferred which means that we - * weren't able to update the next buffer. - * - * So for now we "simulate" NFB by just submitting buffer after buffer - * without double buffering. */ static int m2m_hw_setup(struct ep93xx_dma_chan *edmac) @@ -543,6 +550,11 @@ static void m2m_hw_submit(struct ep93xx_dma_chan *edmac) m2m_fill_desc(edmac); control |= M2M_CONTROL_DONEINT; + if (ep93xx_dma_advance_active(edmac)) { + m2m_fill_desc(edmac); + control |= M2M_CONTROL_NFBINT; + } + /* * Now we can finally enable the channel. For M2M channel this must be * done _after_ the BCRx registers are programmed. @@ -560,32 +572,89 @@ static void m2m_hw_submit(struct ep93xx_dma_chan *edmac) } } +/* + * According to EP93xx User's Guide, we should receive DONE interrupt when all + * M2M DMA controller transactions complete normally. This is not always the + * case - sometimes EP93xx M2M DMA asserts DONE interrupt when the DMA channel + * is still running (channel Buffer FSM in DMA_BUF_ON state, and channel + * Control FSM in DMA_MEM_RD state, observed at least in IDE-DMA operation). + * In effect, disabling the channel when only DONE bit is set could stop + * currently running DMA transfer. To avoid this, we use Buffer FSM and + * Control FSM to check current state of DMA channel. + */ static int m2m_hw_interrupt(struct ep93xx_dma_chan *edmac) { + u32 status = readl(edmac->regs + M2M_STATUS); + u32 ctl_fsm = status & M2M_STATUS_CTL_MASK; + u32 buf_fsm = status & M2M_STATUS_BUF_MASK; + bool done = status & M2M_STATUS_DONE; + bool last_done; u32 control; + struct ep93xx_dma_desc *desc; - if (!(readl(edmac->regs + M2M_INTERRUPT) & M2M_INTERRUPT_DONEINT)) + /* Accept only DONE and NFB interrupts */ + if (!(readl(edmac->regs + M2M_INTERRUPT) & M2M_INTERRUPT_MASK)) return INTERRUPT_UNKNOWN; - /* Clear the DONE bit */ - writel(0, edmac->regs + M2M_INTERRUPT); + if (done) { + /* Clear the DONE bit */ + writel(0, edmac->regs + M2M_INTERRUPT); + } - /* Disable interrupts and the channel */ - control = readl(edmac->regs + M2M_CONTROL); - control &= ~(M2M_CONTROL_DONEINT | M2M_CONTROL_ENABLE); - writel(control, edmac->regs + M2M_CONTROL); + /* + * Check whether we are done with descriptors or not. This, together + * with DMA channel state, determines action to take in interrupt. + */ + desc = ep93xx_dma_get_active(edmac); + last_done = !desc || desc->txd.cookie; /* - * Since we only get DONE interrupt we have to find out ourselves - * whether there still is something to process. So we try to advance - * the chain an see whether it succeeds. + * Use M2M DMA Buffer FSM and Control FSM to check current state of + * DMA channel. Using DONE and NFB bits from channel status register + * or bits from channel interrupt register is not reliable. */ - if (ep93xx_dma_advance_active(edmac)) { - edmac->edma->hw_submit(edmac); - return INTERRUPT_NEXT_BUFFER; + if (!last_done && + (buf_fsm == M2M_STATUS_BUF_NO || + buf_fsm == M2M_STATUS_BUF_ON)) { + /* + * Two buffers are ready for update when Buffer FSM is in + * DMA_NO_BUF state. Only one buffer can be prepared without + * disabling the channel or polling the DONE bit. + * To simplify things, always prepare only one buffer. + */ + if (ep93xx_dma_advance_active(edmac)) { + m2m_fill_desc(edmac); + if (done && !edmac->chan.private) { + /* Software trigger for memcpy channel */ + control = readl(edmac->regs + M2M_CONTROL); + control |= M2M_CONTROL_START; + writel(control, edmac->regs + M2M_CONTROL); + } + return INTERRUPT_NEXT_BUFFER; + } else { + last_done = true; + } + } + + /* + * Disable the channel only when Buffer FSM is in DMA_NO_BUF state + * and Control FSM is in DMA_STALL state. + */ + if (last_done && + buf_fsm == M2M_STATUS_BUF_NO && + ctl_fsm == M2M_STATUS_CTL_STALL) { + /* Disable interrupts and the channel */ + control = readl(edmac->regs + M2M_CONTROL); + control &= ~(M2M_CONTROL_DONEINT | M2M_CONTROL_NFBINT + | M2M_CONTROL_ENABLE); + writel(control, edmac->regs + M2M_CONTROL); + return INTERRUPT_DONE; } - return INTERRUPT_DONE; + /* + * Nothing to do this time. + */ + return INTERRUPT_NEXT_BUFFER; } /* |