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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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