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dma: shdma: transfer based runtime PM
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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>
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Guennadi Liakhovetski authored and Vinod Koul committed Sep 28, 2011
1 parent b4dae6e commit 7a1cd9a
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Showing 2 changed files with 75 additions and 26 deletions.
94 changes: 68 additions & 26 deletions drivers/dma/shdma.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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++;
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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.
Expand All @@ -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) {
Expand Down Expand Up @@ -401,7 +433,6 @@ static int sh_dmae_alloc_chan_resources(struct dma_chan *chan)
etestused:
efindslave:
chan->private = NULL;
pm_runtime_put(sh_chan->dev);
return ret;
}

Expand All @@ -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);
Expand All @@ -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);
}
Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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);
}
}
}

Expand Down Expand Up @@ -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)
Expand All @@ -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,
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
}

Expand Down Expand Up @@ -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;
Expand Down
7 changes: 7 additions & 0 deletions drivers/dma/shdma.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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 {
Expand Down

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