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From: Linus Walleij on 1 Jun 2010 08:30
We only need to write the configuration to a physical channel if
it is free, else it is already written.

Signed-off-by: Jonas Aaberg <jonas.aberg(a)stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij(a)stericsson.com>
---
drivers/dma/ste_dma40.c | 19 +++++++++++++------
1 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 4618d6c..1cd1ff7 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -1211,9 +1211,9 @@ out:
}

static int d40_config_chan(struct d40_chan *d40c,
- struct stedma40_chan_cfg *info)
+ struct stedma40_chan_cfg *info,
+ bool is_free_phy)
{
-
/* Fill in basic CFG register values */
d40_phy_cfg(&d40c->dma_cfg, &d40c->src_def_cfg,
&d40c->dst_def_cfg, d40c->log_num != D40_PHY_CHAN);
@@ -1230,8 +1230,14 @@ static int d40_config_chan(struct d40_chan *d40c,
d40c->dma_cfg.dst_dev_type * 32 + 16;
}

- /* Write channel configuration to the DMA */
- return d40_config_write(d40c);
+ /*
+ * Only write channel configuration to the DMA if the physical
+ * resource is free. In case of multiple logical channels
+ * on the same physical resource, only the first write is necessary.
+ */
+ if (is_free_phy)
+ return d40_config_write(d40c);
+ return 0;
}

static int d40_config_memcpy(struct d40_chan *d40c)
@@ -1691,7 +1697,7 @@ static int d40_alloc_chan_resources(struct dma_chan *chan)
unsigned long flags;
struct d40_chan *d40c =
container_of(chan, struct d40_chan, chan);
-
+ bool is_free_phy;
spin_lock_irqsave(&d40c->lock, flags);

d40c->completed = chan->cookie = 1;
@@ -1705,6 +1711,7 @@ static int d40_alloc_chan_resources(struct dma_chan *chan)
if (err)
goto err_alloc;
}
+ is_free_phy = (d40c->phy_chan == NULL);

err = d40_allocate_channel(d40c);
if (err) {
@@ -1713,7 +1720,7 @@ static int d40_alloc_chan_resources(struct dma_chan *chan)
goto err_alloc;
}

- err = d40_config_chan(d40c, &d40c->dma_cfg);
+ err = d40_config_chan(d40c, &d40c->dma_cfg, is_free_phy);
if (err) {
dev_err(&d40c->chan.dev->device,
"[%s] Failed to configure channel\n",
--
1.6.3.3

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