dma: shdma: transfer based runtime PM

Currently the shdma dmaengine driver uses runtime PM to save power, when
no channel on the specific controller is requested by a user. This patch
switches the driver to count individual DMA transfers. That way the
controller can be powered down between transfers, even if some of its
channels are in use.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c
index e7bb747..81809c2 100644 (file)
--- a/drivers/dma/shdma.c
+++ b/drivers/dma/shdma.c
@@ -259,15 +259,23 @@ static int dmae_set_dmars(struct sh_dmae_chan *sh_chan, u16 val)
        return 0;
 }
 
+static void sh_chan_xfer_ld_queue(struct sh_dmae_chan *sh_chan);
+
 static dma_cookie_t sh_dmae_tx_submit(struct dma_async_tx_descriptor *tx)
 {
        struct sh_desc *desc = tx_to_sh_desc(tx), *chunk, *last = desc, *c;
        struct sh_dmae_chan *sh_chan = to_sh_chan(tx->chan);
+       struct sh_dmae_slave *param = tx->chan->private;
        dma_async_tx_callback callback = tx->callback;
        dma_cookie_t cookie;
-       unsigned long flags;
+       bool power_up;
 
-       spin_lock_irqsave(&sh_chan->desc_lock, flags);
+       spin_lock_irq(&sh_chan->desc_lock);
+
+       if (list_empty(&sh_chan->ld_queue))
+               power_up = true;
+       else
+               power_up = false;
 
        cookie = sh_chan->common.cookie;
        cookie++;
@@ -303,7 +311,38 @@ static dma_cookie_t sh_dmae_tx_submit(struct dma_async_tx_descriptor *tx)
                tx->cookie, &last->async_tx, sh_chan->id,
                desc->hw.sar, desc->hw.tcr, desc->hw.dar);
 
-       spin_unlock_irqrestore(&sh_chan->desc_lock, flags);
+       if (power_up) {
+               sh_chan->pm_state = DMAE_PM_BUSY;
+
+               pm_runtime_get(sh_chan->dev);
+
+               spin_unlock_irq(&sh_chan->desc_lock);
+
+               pm_runtime_barrier(sh_chan->dev);
+
+               spin_lock_irq(&sh_chan->desc_lock);
+
+               /* Have we been reset, while waiting? */
+               if (sh_chan->pm_state != DMAE_PM_ESTABLISHED) {
+                       dev_dbg(sh_chan->dev, "Bring up channel %d\n",
+                               sh_chan->id);
+                       if (param) {
+                               const struct sh_dmae_slave_config *cfg =
+                                       param->config;
+
+                               dmae_set_dmars(sh_chan, cfg->mid_rid);
+                               dmae_set_chcr(sh_chan, cfg->chcr);
+                       } else {
+                               dmae_init(sh_chan);
+                       }
+
+                       if (sh_chan->pm_state == DMAE_PM_PENDING)
+                               sh_chan_xfer_ld_queue(sh_chan);
+                       sh_chan->pm_state = DMAE_PM_ESTABLISHED;
+               }
+       }
+
+       spin_unlock_irq(&sh_chan->desc_lock);
 
        return cookie;
 }
@@ -347,8 +386,6 @@ static int sh_dmae_alloc_chan_resources(struct dma_chan *chan)
        struct sh_dmae_slave *param = chan->private;
        int ret;
 
-       pm_runtime_get_sync(sh_chan->dev);
-
        /*
         * This relies on the guarantee from dmaengine that alloc_chan_resources
         * never runs concurrently with itself or free_chan_resources.
@@ -368,11 +405,6 @@ static int sh_dmae_alloc_chan_resources(struct dma_chan *chan)
                }
 
                param->config = cfg;
-
-               dmae_set_dmars(sh_chan, cfg->mid_rid);
-               dmae_set_chcr(sh_chan, cfg->chcr);
-       } else {
-               dmae_init(sh_chan);
        }
 
        while (sh_chan->descs_allocated < NR_DESCS_PER_CHANNEL) {
@@ -401,7 +433,6 @@ edescalloc:
 etestused:
 efindslave:
        chan->private = NULL;
-       pm_runtime_put(sh_chan->dev);
        return ret;
 }
 
@@ -413,7 +444,6 @@ static void sh_dmae_free_chan_resources(struct dma_chan *chan)
        struct sh_dmae_chan *sh_chan = to_sh_chan(chan);
        struct sh_desc *desc, *_desc;
        LIST_HEAD(list);
-       int descs = sh_chan->descs_allocated;
 
        /* Protect against ISR */
        spin_lock_irq(&sh_chan->desc_lock);
@@ -440,9 +470,6 @@ static void sh_dmae_free_chan_resources(struct dma_chan *chan)
 
        spin_unlock_irq(&sh_chan->desc_lock);
 
-       if (descs > 0)
-               pm_runtime_put(sh_chan->dev);
-
        list_for_each_entry_safe(desc, _desc, &list, node)
                kfree(desc);
 }
@@ -676,7 +703,6 @@ static int sh_dmae_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                                                  struct sh_desc, node);
                desc->partial = (desc->hw.tcr - sh_dmae_readl(sh_chan, TCR)) <<
                        sh_chan->xmit_shift;
-
        }
        spin_unlock_irqrestore(&sh_chan->desc_lock, flags);
 
@@ -761,7 +787,13 @@ static dma_async_tx_callback __ld_cleanup(struct sh_dmae_chan *sh_chan, bool all
                     async_tx_test_ack(&desc->async_tx)) || all) {
                        /* Remove from ld_queue list */
                        desc->mark = DESC_IDLE;
+
                        list_move(&desc->node, &sh_chan->ld_free);
+
+                       if (list_empty(&sh_chan->ld_queue)) {
+                               dev_dbg(sh_chan->dev, "Bring down channel %d\n", sh_chan->id);
+                               pm_runtime_put(sh_chan->dev);
+                       }
                }
        }
 
@@ -791,16 +823,14 @@ static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan, bool all)
                ;
 }
 
+/* Called under spin_lock_irq(&sh_chan->desc_lock) */
 static void sh_chan_xfer_ld_queue(struct sh_dmae_chan *sh_chan)
 {
        struct sh_desc *desc;
 
-       spin_lock_irq(&sh_chan->desc_lock);
        /* DMA work check */
-       if (dmae_is_busy(sh_chan)) {
-               spin_unlock_irq(&sh_chan->desc_lock);
+       if (dmae_is_busy(sh_chan))
                return;
-       }
 
        /* Find the first not transferred descriptor */
        list_for_each_entry(desc, &sh_chan->ld_queue, node)
@@ -813,14 +843,18 @@ static void sh_chan_xfer_ld_queue(struct sh_dmae_chan *sh_chan)
                        dmae_start(sh_chan);
                        break;
                }
-
-       spin_unlock_irq(&sh_chan->desc_lock);
 }
 
 static void sh_dmae_memcpy_issue_pending(struct dma_chan *chan)
 {
        struct sh_dmae_chan *sh_chan = to_sh_chan(chan);
-       sh_chan_xfer_ld_queue(sh_chan);
+
+       spin_lock_irq(&sh_chan->desc_lock);
+       if (sh_chan->pm_state == DMAE_PM_ESTABLISHED)
+               sh_chan_xfer_ld_queue(sh_chan);
+       else
+               sh_chan->pm_state = DMAE_PM_PENDING;
+       spin_unlock_irq(&sh_chan->desc_lock);
 }
 
 static enum dma_status sh_dmae_tx_status(struct dma_chan *chan,
@@ -913,6 +947,12 @@ static bool sh_dmae_reset(struct sh_dmae_device *shdev)
 
                list_splice_init(&sh_chan->ld_queue, &dl);
 
+               if (!list_empty(&dl)) {
+                       dev_dbg(sh_chan->dev, "Bring down channel %d\n", sh_chan->id);
+                       pm_runtime_put(sh_chan->dev);
+               }
+               sh_chan->pm_state = DMAE_PM_ESTABLISHED;
+
                spin_unlock(&sh_chan->desc_lock);
 
                /* Complete all  */
@@ -966,10 +1006,10 @@ static void dmae_do_tasklet(unsigned long data)
                        break;
                }
        }
-       spin_unlock_irq(&sh_chan->desc_lock);
-
        /* Next desc */
        sh_chan_xfer_ld_queue(sh_chan);
+       spin_unlock_irq(&sh_chan->desc_lock);
+
        sh_dmae_chan_ld_cleanup(sh_chan, false);
 }
 
@@ -1037,7 +1077,9 @@ static int __devinit sh_dmae_chan_probe(struct sh_dmae_device *shdev, int id,
                return -ENOMEM;
        }
 
-       /* copy struct dma_device */
+       new_sh_chan->pm_state = DMAE_PM_ESTABLISHED;
+
+       /* reference struct dma_device */
        new_sh_chan->common.device = &shdev->common;
 
        new_sh_chan->dev = shdev->common.dev;

diff --git a/drivers/dma/shdma.h b/drivers/dma/shdma.h
index dc56576..2b55a27 100644 (file)
--- a/drivers/dma/shdma.h
+++ b/drivers/dma/shdma.h
@@ -23,6 +23,12 @@
 
 struct device;
 
+enum dmae_pm_state {
+       DMAE_PM_ESTABLISHED,
+       DMAE_PM_BUSY,
+       DMAE_PM_PENDING,
+};
+
 struct sh_dmae_chan {
        dma_cookie_t completed_cookie;  /* The maximum cookie completed */
        spinlock_t desc_lock;           /* Descriptor operation lock */
@@ -38,6 +44,7 @@ struct sh_dmae_chan {
        u32 __iomem *base;
        char dev_id[16];                /* unique name per DMAC of channel */
        int pm_error;
+       enum dmae_pm_state pm_state;
 };
 
 struct sh_dmae_device {