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Subject[PATCH 6/8] dmaengine/dw_dmac: Don't handle block interrupts
Date
Block interrupts give interrupt on completion of every LLI, which is actually
too much interrupts. This is just not required for current functioning of
dw_dmac.

So, just don't handle them at all.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
---
drivers/dma/dw_dmac.c | 36 ++++++------------------------------
1 files changed, 6 insertions(+), 30 deletions(-)
diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index f061daa..8698d3b 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -192,7 +192,6 @@ static void dwc_initialize(struct dw_dma_chan *dwc)

/* Enable interrupts */
channel_set_bit(dw, MASK.XFER, dwc->mask);
- channel_set_bit(dw, MASK.BLOCK, dwc->mask);
channel_set_bit(dw, MASK.ERROR, dwc->mask);

dwc->initialized = true;
@@ -329,12 +328,6 @@ static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)
unsigned long flags;

spin_lock_irqsave(&dwc->lock, flags);
- /*
- * Clear block interrupt flag before scanning so that we don't
- * miss any, and read LLP before RAW_XFER to ensure it is
- * valid if we decide to scan the list.
- */
- dma_writel(dw, CLEAR.BLOCK, dwc->mask);
llp = channel_readl(dwc, LLP);
status_xfer = dma_readl(dw, RAW.XFER);

@@ -470,17 +463,16 @@ EXPORT_SYMBOL(dw_dma_get_dst_addr);

/* called with dwc->lock held and all DMAC interrupts disabled */
static void dwc_handle_cyclic(struct dw_dma *dw, struct dw_dma_chan *dwc,
- u32 status_block, u32 status_err, u32 status_xfer)
+ u32 status_err, u32 status_xfer)
{
unsigned long flags;

- if (status_block & dwc->mask) {
+ if (dwc->mask) {
void (*callback)(void *param);
void *callback_param;

dev_vdbg(chan2dev(&dwc->chan), "new cyclic period llp 0x%08x\n",
channel_readl(dwc, LLP));
- dma_writel(dw, CLEAR.BLOCK, dwc->mask);

callback = dwc->cdesc->period_callback;
callback_param = dwc->cdesc->period_callback_param;
@@ -520,7 +512,6 @@ static void dwc_handle_cyclic(struct dw_dma *dw, struct dw_dma_chan *dwc,
channel_writel(dwc, CTL_LO, 0);
channel_writel(dwc, CTL_HI, 0);

- dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);

@@ -537,36 +528,29 @@ static void dw_dma_tasklet(unsigned long data)
{
struct dw_dma *dw = (struct dw_dma *)data;
struct dw_dma_chan *dwc;
- u32 status_block;
u32 status_xfer;
u32 status_err;
int i;

- status_block = dma_readl(dw, RAW.BLOCK);
status_xfer = dma_readl(dw, RAW.XFER);
status_err = dma_readl(dw, RAW.ERROR);

- dev_vdbg(dw->dma.dev, "tasklet: status_block=%x status_err=%x\n",
- status_block, status_err);
+ dev_vdbg(dw->dma.dev, "tasklet: status_err=%x\n", status_err);

for (i = 0; i < dw->dma.chancnt; i++) {
dwc = &dw->chan[i];
if (test_bit(DW_DMA_IS_CYCLIC, &dwc->flags))
- dwc_handle_cyclic(dw, dwc, status_block, status_err,
- status_xfer);
+ dwc_handle_cyclic(dw, dwc, status_err, status_xfer);
else if (status_err & (1 << i))
dwc_handle_error(dw, dwc);
- else if ((status_block | status_xfer) & (1 << i))
+ else if (status_xfer & (1 << i))
dwc_scan_descriptors(dw, dwc);
}

/*
- * Re-enable interrupts. Block Complete interrupts are only
- * enabled if the INT_EN bit in the descriptor is set. This
- * will trigger a scan before the whole list is done.
+ * Re-enable interrupts.
*/
channel_set_bit(dw, MASK.XFER, dw->all_chan_mask);
- channel_set_bit(dw, MASK.BLOCK, dw->all_chan_mask);
channel_set_bit(dw, MASK.ERROR, dw->all_chan_mask);
}

@@ -583,7 +567,6 @@ static irqreturn_t dw_dma_interrupt(int irq, void *dev_id)
* softirq handler.
*/
channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
- channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);
channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);

status = dma_readl(dw, STATUS_INT);
@@ -594,7 +577,6 @@ static irqreturn_t dw_dma_interrupt(int irq, void *dev_id)

/* Try to recover */
channel_clear_bit(dw, MASK.XFER, (1 << 8) - 1);
- channel_clear_bit(dw, MASK.BLOCK, (1 << 8) - 1);
channel_clear_bit(dw, MASK.SRC_TRAN, (1 << 8) - 1);
channel_clear_bit(dw, MASK.DST_TRAN, (1 << 8) - 1);
channel_clear_bit(dw, MASK.ERROR, (1 << 8) - 1);
@@ -1068,7 +1050,6 @@ static void dwc_free_chan_resources(struct dma_chan *chan)

/* Disable interrupts */
channel_clear_bit(dw, MASK.XFER, dwc->mask);
- channel_clear_bit(dw, MASK.BLOCK, dwc->mask);
channel_clear_bit(dw, MASK.ERROR, dwc->mask);

spin_unlock_irqrestore(&dwc->lock, flags);
@@ -1120,7 +1101,6 @@ int dw_dma_cyclic_start(struct dma_chan *chan)
return -EBUSY;
}

- dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);

@@ -1322,7 +1302,6 @@ void dw_dma_cyclic_free(struct dma_chan *chan)
while (dma_readl(dw, CH_EN) & dwc->mask)
cpu_relax();

- dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);

@@ -1347,7 +1326,6 @@ static void dw_dma_off(struct dw_dma *dw)
dma_writel(dw, CFG, 0);

channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
- channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);
channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask);
channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask);
channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);
@@ -1449,13 +1427,11 @@ static int __init dw_probe(struct platform_device *pdev)

/* Clear/disable all interrupts on all channels. */
dma_writel(dw, CLEAR.XFER, dw->all_chan_mask);
- dma_writel(dw, CLEAR.BLOCK, dw->all_chan_mask);
dma_writel(dw, CLEAR.SRC_TRAN, dw->all_chan_mask);
dma_writel(dw, CLEAR.DST_TRAN, dw->all_chan_mask);
dma_writel(dw, CLEAR.ERROR, dw->all_chan_mask);

channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask);
- channel_clear_bit(dw, MASK.BLOCK, dw->all_chan_mask);
channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask);
channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask);
channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask);
--
1.7.8.110.g4cb5d


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