summaryrefslogtreecommitdiffstats
path: root/drivers/dma
diff options
context:
space:
mode:
authorRussell King <rmk+kernel@arm.linux.org.uk>2012-05-25 11:32:45 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-07-01 14:15:50 +0100
commit5e2479bd0e0dc41f2b9f6b4345bc5d4557837056 (patch)
tree4822ee508024f5470cebfda8a1312e82ee05415b /drivers/dma
parentad0de2ac3218d372149d89d9d5c5058aca6aa29b (diff)
downloadlinux-5e2479bd0e0dc41f2b9f6b4345bc5d4557837056.tar.bz2
dmaengine: PL08x: track mux usage on a per-channel basis.
Keep track of the number of descriptors currently using a MUX setting on a per-channel basis. This allows us to know when we have descriptors queued somewhere which have been assigned a DMA request signal. 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>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/amba-pl08x.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index c203d2f22bca..ac9fdccb2c19 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -227,6 +227,7 @@ enum pl08x_dma_chan_state {
* @waiting: a TX descriptor on this channel which is waiting for a physical
* channel to become available
* @signal: the physical DMA request signal which this channel is using
+ * @mux_use: count of descriptors using this DMA request signal setting
*/
struct pl08x_dma_chan {
struct dma_chan chan;
@@ -244,6 +245,7 @@ struct pl08x_dma_chan {
bool slave;
struct pl08x_txd *waiting;
int signal;
+ unsigned mux_use;
};
/**
@@ -310,10 +312,12 @@ static int pl08x_request_mux(struct pl08x_dma_chan *plchan)
const struct pl08x_platform_data *pd = plchan->host->pd;
int ret;
- if (pd->get_signal) {
+ if (plchan->mux_use++ == 0 && pd->get_signal) {
ret = pd->get_signal(plchan->cd);
- if (ret < 0)
+ if (ret < 0) {
+ plchan->mux_use = 0;
return ret;
+ }
plchan->signal = ret;
}
@@ -324,9 +328,13 @@ static void pl08x_release_mux(struct pl08x_dma_chan *plchan)
{
const struct pl08x_platform_data *pd = plchan->host->pd;
- if (plchan->signal >= 0 && pd->put_signal) {
- pd->put_signal(plchan->cd, plchan->signal);
- plchan->signal = -1;
+ if (plchan->signal >= 0) {
+ WARN_ON(plchan->mux_use == 0);
+
+ if (--plchan->mux_use == 0 && pd->put_signal) {
+ pd->put_signal(plchan->cd, plchan->signal);
+ plchan->signal = -1;
+ }
}
}