dw_dmac: allocate dma descriptors from DMA_COHERENT memory

Currently descriptors are allocated from normal cacheable memory and that slows
down filling the descriptors, as we need to call cache_coherency routines
afterwards. It would be better to allocate memory for these descriptors from
DMA_COHERENT memory. This would make code much cleaner too.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 28d5f01..76301c4 100644 (file)
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -14,6 +14,7 @@
 #include <linux/delay.h>
 #include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
@@ -91,14 +92,6 @@ static inline unsigned int dwc_get_data_width(struct dma_chan *chan, int master)
 
 /*----------------------------------------------------------------------*/
 
-/*
- * Because we're not relying on writeback from the controller (it may not
- * even be configured into the core!) we don't need to use dma_pool.  These
- * descriptors -- and associated data -- are cacheable.  We do need to make
- * sure their dcache entries are written back before handing them off to
- * the controller, though.
- */
-
 static struct device *chan2dev(struct dma_chan *chan)
 {
        return &chan->dev->device;
@@ -137,19 +130,6 @@ static struct dw_desc *dwc_desc_get(struct dw_dma_chan *dwc)
        return ret;
 }
 
-static void dwc_sync_desc_for_cpu(struct dw_dma_chan *dwc, struct dw_desc *desc)
-{
-       struct dw_desc  *child;
-
-       list_for_each_entry(child, &desc->tx_list, desc_node)
-               dma_sync_single_for_cpu(chan2parent(&dwc->chan),
-                               child->txd.phys, sizeof(child->lli),
-                               DMA_TO_DEVICE);
-       dma_sync_single_for_cpu(chan2parent(&dwc->chan),
-                       desc->txd.phys, sizeof(desc->lli),
-                       DMA_TO_DEVICE);
-}
-
 /*
  * Move a descriptor, including any children, to the free list.
  * `desc' must not be on any lists.
@@ -161,8 +141,6 @@ static void dwc_desc_put(struct dw_dma_chan *dwc, struct dw_desc *desc)
        if (desc) {
                struct dw_desc *child;
 
-               dwc_sync_desc_for_cpu(dwc, desc);
-
                spin_lock_irqsave(&dwc->lock, flags);
                list_for_each_entry(child, &desc->tx_list, desc_node)
                        dev_vdbg(chan2dev(&dwc->chan),
@@ -335,8 +313,6 @@ dwc_descriptor_complete(struct dw_dma_chan *dwc, struct dw_desc *desc,
                param = txd->callback_param;
        }
 
-       dwc_sync_desc_for_cpu(dwc, desc);
-
        /* async_tx_ack */
        list_for_each_entry(child, &desc->tx_list, desc_node)
                async_tx_ack(&child->txd);
@@ -770,25 +746,17 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                        first = desc;
                } else {
                        prev->lli.llp = desc->txd.phys;
-                       dma_sync_single_for_device(chan2parent(chan),
-                                       prev->txd.phys, sizeof(prev->lli),
-                                       DMA_TO_DEVICE);
                        list_add_tail(&desc->desc_node,
                                        &first->tx_list);
                }
                prev = desc;
        }
 
-
        if (flags & DMA_PREP_INTERRUPT)
                /* Trigger interrupt after last block */
                prev->lli.ctllo |= DWC_CTLL_INT_EN;
 
        prev->lli.llp = 0;
-       dma_sync_single_for_device(chan2parent(chan),
-                       prev->txd.phys, sizeof(prev->lli),
-                       DMA_TO_DEVICE);
-
        first->txd.flags = flags;
        first->len = len;
 
@@ -876,10 +844,6 @@ slave_sg_todev_fill_desc:
                                first = desc;
                        } else {
                                prev->lli.llp = desc->txd.phys;
-                               dma_sync_single_for_device(chan2parent(chan),
-                                               prev->txd.phys,
-                                               sizeof(prev->lli),
-                                               DMA_TO_DEVICE);
                                list_add_tail(&desc->desc_node,
                                                &first->tx_list);
                        }
@@ -938,10 +902,6 @@ slave_sg_fromdev_fill_desc:
                                first = desc;
                        } else {
                                prev->lli.llp = desc->txd.phys;
-                               dma_sync_single_for_device(chan2parent(chan),
-                                               prev->txd.phys,
-                                               sizeof(prev->lli),
-                                               DMA_TO_DEVICE);
                                list_add_tail(&desc->desc_node,
                                                &first->tx_list);
                        }
@@ -961,10 +921,6 @@ slave_sg_fromdev_fill_desc:
                prev->lli.ctllo |= DWC_CTLL_INT_EN;
 
        prev->lli.llp = 0;
-       dma_sync_single_for_device(chan2parent(chan),
-                       prev->txd.phys, sizeof(prev->lli),
-                       DMA_TO_DEVICE);
-
        first->len = total_len;
 
        return &first->txd;
@@ -1118,7 +1074,6 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
        struct dw_desc          *desc;
        int                     i;
        unsigned long           flags;
-       int                     ret;
 
        dev_vdbg(chan2dev(chan), "%s\n", __func__);
 
@@ -1139,21 +1094,21 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
        spin_lock_irqsave(&dwc->lock, flags);
        i = dwc->descs_allocated;
        while (dwc->descs_allocated < NR_DESCS_PER_CHANNEL) {
+               dma_addr_t phys;
+
                spin_unlock_irqrestore(&dwc->lock, flags);
 
-               desc = kzalloc(sizeof(struct dw_desc), GFP_KERNEL);
+               desc = dma_pool_alloc(dw->desc_pool, GFP_ATOMIC, &phys);
                if (!desc)
                        goto err_desc_alloc;
 
+               memset(desc, 0, sizeof(struct dw_desc));
+
                INIT_LIST_HEAD(&desc->tx_list);
                dma_async_tx_descriptor_init(&desc->txd, chan);
                desc->txd.tx_submit = dwc_tx_submit;
                desc->txd.flags = DMA_CTRL_ACK;
-               desc->txd.phys = dma_map_single(chan2parent(chan), &desc->lli,
-                               sizeof(desc->lli), DMA_TO_DEVICE);
-               ret = dma_mapping_error(chan2parent(chan), desc->txd.phys);
-               if (ret)
-                       goto err_desc_alloc;
+               desc->txd.phys = phys;
 
                dwc_desc_put(dwc, desc);
 
@@ -1168,8 +1123,6 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
        return i;
 
 err_desc_alloc:
-       kfree(desc);
-
        dev_info(chan2dev(chan), "only allocated %d descriptors\n", i);
 
        return i;
@@ -1204,9 +1157,7 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
 
        list_for_each_entry_safe(desc, _desc, &list, desc_node) {
                dev_vdbg(chan2dev(chan), "  freeing descriptor %p\n", desc);
-               dma_unmap_single(chan2parent(chan), desc->txd.phys,
-                               sizeof(desc->lli), DMA_TO_DEVICE);
-               kfree(desc);
+               dma_pool_free(dw->desc_pool, desc, desc->txd.phys);
        }
 
        dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
@@ -1451,20 +1402,14 @@ struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
                desc->lli.ctlhi = (period_len >> reg_width);
                cdesc->desc[i] = desc;
 
-               if (last) {
+               if (last)
                        last->lli.llp = desc->txd.phys;
-                       dma_sync_single_for_device(chan2parent(chan),
-                                       last->txd.phys, sizeof(last->lli),
-                                       DMA_TO_DEVICE);
-               }
 
                last = desc;
        }
 
        /* lets make a cyclic list */
        last->lli.llp = cdesc->desc[0]->txd.phys;
-       dma_sync_single_for_device(chan2parent(chan), last->txd.phys,
-                       sizeof(last->lli), DMA_TO_DEVICE);
 
        dev_dbg(chan2dev(&dwc->chan), "cyclic prepared buf 0x%llx len %zu "
                        "period %zu periods %d\n", (unsigned long long)buf_addr,
@@ -1722,6 +1667,14 @@ static int dw_probe(struct platform_device *pdev)
 
        platform_set_drvdata(pdev, dw);
 
+       /* create a pool of consistent memory blocks for hardware descriptors */
+       dw->desc_pool = dmam_pool_create("dw_dmac_desc_pool", &pdev->dev,
+                                        sizeof(struct dw_desc), 4, 0);
+       if (!dw->desc_pool) {
+               dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
+               return -ENOMEM;
+       }
+
        tasklet_init(&dw->tasklet, dw_dma_tasklet, (unsigned long)dw);
 
        INIT_LIST_HEAD(&dw->dma.channels);

diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
index 577f2dd..fef296d 100644 (file)
--- a/drivers/dma/dw_dmac_regs.h
+++ b/drivers/dma/dw_dmac_regs.h
@@ -235,6 +235,7 @@ static inline struct dw_dma_chan *to_dw_dma_chan(struct dma_chan *chan)
 struct dw_dma {
        struct dma_device       dma;
        void __iomem            *regs;
+       struct dma_pool         *desc_pool;
        struct tasklet_struct   tasklet;
        struct clk              *clk;