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dmaengine: PL08x: move DMA signal muxing into slave prepare code
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Move the DMA request muxing into the slave prepare code and txd
release/completion code.  This means we only hold the DMA request
mux while there are descriptors waiting to be started or are in
progress.

This leaves txd->direction as a write-only variable; remove it.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Russell King committed Jul 1, 2012
1 parent a936e79 commit c48d496
Showing 1 changed file with 32 additions and 47 deletions.
79 changes: 32 additions & 47 deletions drivers/dma/amba-pl08x.c
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Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,6 @@ struct pl08x_sg {
* @tx: async tx descriptor
* @node: node for txd list for channels
* @dsg_list: list of children sg's
* @direction: direction of transfer
* @llis_bus: DMA memory address (physical) start for the LLIs
* @llis_va: virtual memory address start for the LLIs
* @cctl: control reg values for current txd
Expand All @@ -178,7 +177,6 @@ struct pl08x_txd {
struct dma_async_tx_descriptor tx;
struct list_head node;
struct list_head dsg_list;
enum dma_transfer_direction direction;
dma_addr_t llis_bus;
struct pl08x_lli *llis_va;
/* Default cctl value for LLIs */
Expand Down Expand Up @@ -997,6 +995,7 @@ static void pl08x_free_txd_list(struct pl08x_driver_data *pl08x,
if (!list_empty(&plchan->pend_list)) {
list_for_each_entry_safe(txdi,
next, &plchan->pend_list, node) {
pl08x_release_mux(plchan);
list_del(&txdi->node);
pl08x_free_txd(pl08x, txdi);
}
Expand All @@ -1018,12 +1017,10 @@ static void pl08x_free_chan_resources(struct dma_chan *chan)
/*
* This should be called with the channel plchan->lock held
*/
static int prep_phy_channel(struct pl08x_dma_chan *plchan,
struct pl08x_txd *txd)
static int prep_phy_channel(struct pl08x_dma_chan *plchan)
{
struct pl08x_driver_data *pl08x = plchan->host;
struct pl08x_phy_chan *ch;
int ret;

/* Check if we already have a channel */
if (plchan->phychan) {
Expand All @@ -1038,36 +1035,11 @@ static int prep_phy_channel(struct pl08x_dma_chan *plchan,
return -EBUSY;
}

/*
* OK we have a physical channel: for memcpy() this is all we
* need, but for slaves the physical signals may be muxed!
* Can the platform allow us to use this channel?
*/
if (plchan->slave) {
ret = pl08x_request_mux(plchan);
if (ret < 0) {
dev_dbg(&pl08x->adev->dev,
"unable to use physical channel %d for transfer on %s due to platform restrictions\n",
ch->id, plchan->name);
/* Release physical channel & return */
pl08x_put_phy_channel(pl08x, ch);
return -EBUSY;
}
}

plchan->phychan = ch;
dev_dbg(&pl08x->adev->dev, "allocated physical channel %d and signal %d for xfer on %s\n",
ch->id,
plchan->signal,
plchan->name);
dev_dbg(&pl08x->adev->dev, "allocated physical channel %d for xfer on %s\n",
ch->id, plchan->name);

got_channel:
/* Assign the flow control signal to this channel */
if (txd->direction == DMA_MEM_TO_DEV)
txd->ccfg |= plchan->signal << PL080_CONFIG_DST_SEL_SHIFT;
else if (txd->direction == DMA_DEV_TO_MEM)
txd->ccfg |= plchan->signal << PL080_CONFIG_SRC_SEL_SHIFT;

plchan->phychan_hold++;

return 0;
Expand All @@ -1077,7 +1049,6 @@ static void release_phy_channel(struct pl08x_dma_chan *plchan)
{
struct pl08x_driver_data *pl08x = plchan->host;

pl08x_release_mux(plchan);
pl08x_put_phy_channel(pl08x, plchan->phychan);
plchan->phychan = NULL;
}
Expand Down Expand Up @@ -1340,19 +1311,12 @@ static int pl08x_prep_channel_resources(struct pl08x_dma_chan *plchan,
* See if we already have a physical channel allocated,
* else this is the time to try to get one.
*/
ret = prep_phy_channel(plchan, txd);
ret = prep_phy_channel(plchan);
if (ret) {
/*
* No physical channel was available.
*
* memcpy transfers can be sorted out at submission time.
*
* Slave transfers may have been denied due to platform
* channel muxing restrictions. Since there is no guarantee
* that this will ever be resolved, and the signal must be
* acquired AFTER acquiring the physical channel, we will let
* them be NACK:ed with -EBUSY here. The drivers can retry
* the prep() call if they are eager on doing this using DMA.
*/
if (plchan->slave) {
pl08x_free_txd_list(pl08x, plchan);
Expand Down Expand Up @@ -1423,7 +1387,6 @@ static struct dma_async_tx_descriptor *pl08x_prep_dma_memcpy(
}
list_add_tail(&dsg->node, &txd->dsg_list);

txd->direction = DMA_MEM_TO_MEM;
dsg->src_addr = src;
dsg->dst_addr = dest;
dsg->len = len;
Expand Down Expand Up @@ -1477,8 +1440,6 @@ static struct dma_async_tx_descriptor *pl08x_prep_slave_sg(
* will take precedence since this may configure the
* channel target address dynamically at runtime.
*/
txd->direction = direction;

if (direction == DMA_MEM_TO_DEV) {
cctl = PL080_CONTROL_SRC_INCR;
slave_addr = plchan->cfg.dst_addr;
Expand Down Expand Up @@ -1519,9 +1480,28 @@ static struct dma_async_tx_descriptor *pl08x_prep_slave_sg(

txd->ccfg |= tmp << PL080_CONFIG_FLOW_CONTROL_SHIFT;

ret = pl08x_request_mux(plchan);
if (ret < 0) {
pl08x_free_txd(pl08x, txd);
dev_dbg(&pl08x->adev->dev,
"unable to mux for transfer on %s due to platform restrictions\n",
plchan->name);
return NULL;
}

dev_dbg(&pl08x->adev->dev, "allocated DMA request signal %d for xfer on %s\n",
plchan->signal, plchan->name);

/* Assign the flow control signal to this channel */
if (direction == DMA_MEM_TO_DEV)
txd->ccfg |= plchan->signal << PL080_CONFIG_DST_SEL_SHIFT;
else
txd->ccfg |= plchan->signal << PL080_CONFIG_SRC_SEL_SHIFT;

for_each_sg(sgl, sg, sg_len, tmp) {
dsg = kzalloc(sizeof(struct pl08x_sg), GFP_NOWAIT);
if (!dsg) {
pl08x_release_mux(plchan);
pl08x_free_txd(pl08x, txd);
dev_err(&pl08x->adev->dev, "%s no mem for pl080 sg\n",
__func__);
Expand Down Expand Up @@ -1586,6 +1566,8 @@ static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
}
/* Dequeue jobs and free LLIs */
if (plchan->at) {
/* Killing this one off, release its mux */
pl08x_release_mux(plchan);
pl08x_free_txd(pl08x, plchan->at);
plchan->at = NULL;
}
Expand Down Expand Up @@ -1702,7 +1684,6 @@ static void pl08x_tasklet(unsigned long data)

/*
* No more jobs, so free up the physical channel
* Free any allocated signal on slave transfers too
*/
release_phy_channel(plchan);
plchan->state = PL08X_CHAN_IDLE;
Expand All @@ -1720,8 +1701,7 @@ static void pl08x_tasklet(unsigned long data)
int ret;

/* This should REALLY not fail now */
ret = prep_phy_channel(waiting,
waiting->waiting);
ret = prep_phy_channel(waiting);
BUG_ON(ret);
waiting->phychan_hold--;
waiting->state = PL08X_CHAN_RUNNING;
Expand Down Expand Up @@ -1794,6 +1774,11 @@ static irqreturn_t pl08x_irq(int irq, void *dev)
tx = plchan->at;
if (tx) {
plchan->at = NULL;
/*
* This descriptor is done, release its mux
* reservation.
*/
pl08x_release_mux(plchan);
dma_cookie_complete(&tx->tx);
list_add_tail(&tx->node, &plchan->done_list);
}
Expand Down

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