dmaengine: axi-dmac: Use only EOT interrupts when doing scatter-gather

Instead of notifying userspace in the end-of-transfer (EOT) interrupt
and program the hardware in the start-of-transfer (SOT) interrupt, we
can do both things in the EOT, allowing us to mask the SOT, and halve
the number of interrupts sent by the HDL core.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20231215131313.23840-5-paul@crapouillou.net
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
index 5109530b66de98836f85897c069705fd5fbe2f9d..f63acae511fb2a6769bab7fbdc92c974f8d704ab 100644 (file)
--- a/drivers/dma/dma-axi-dmac.c
+++ b/drivers/dma/dma-axi-dmac.c
@@ -411,10 +411,12 @@ static bool axi_dmac_transfer_done(struct axi_dmac_chan *chan,
        if (chan->hw_sg) {
                if (active->cyclic) {
                        vchan_cyclic_callback(&active->vdesc);
+                       start_next = true;
                } else {
                        list_del(&active->vdesc.node);
                        vchan_cookie_complete(&active->vdesc);
                        active = axi_dmac_active_desc(chan);
+                       start_next = !!active;
                }
        } else {
                do {
@@ -1000,6 +1002,7 @@ static int axi_dmac_probe(struct platform_device *pdev)
        struct axi_dmac *dmac;
        struct regmap *regmap;
        unsigned int version;
+       u32 irq_mask = 0;
        int ret;
 
        dmac = devm_kzalloc(&pdev->dev, sizeof(*dmac), GFP_KERNEL);
@@ -1067,7 +1070,10 @@ static int axi_dmac_probe(struct platform_device *pdev)
 
        dma_dev->copy_align = (dmac->chan.address_align_mask + 1);
 
-       axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00);
+       if (dmac->chan.hw_sg)
+               irq_mask |= AXI_DMAC_IRQ_SOT;
+
+       axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, irq_mask);
 
        if (of_dma_is_coherent(pdev->dev.of_node)) {
                ret = axi_dmac_read(dmac, AXI_DMAC_REG_COHERENCY_DESC);