#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)
#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
/*
* 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)
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.
}
}
+/*
+ * 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;
}
/*
projects / karo-tx-linux.git / commitdiff