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Subject[PATCH v3 02/15] dmaengine: omap: Add support for pause/resume in cyclic dma mode
Date
The audio stack used omap_stop_dma/omap_start_dma to pause/resume the DMA.
This method has been used for years on OMAP based products.
We only allow pause/resume when the DMA has been configured in cyclic mode
which is used by the audio stack.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
CC: Russell King <rmk+kernel@arm.linux.org.uk>
---
drivers/dma/omap-dma.c | 30 +++++++++++++++++++++++++-----
1 file changed, 25 insertions(+), 5 deletions(-)
diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index b77a40d..71d7869 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c
@@ -34,6 +34,7 @@ struct omap_chan {
struct dma_slave_config cfg;
unsigned dma_sig;
bool cyclic;
+ bool paused;

int dma_ch;
struct omap_desc *desc;
@@ -470,11 +471,14 @@ static int omap_dma_terminate_all(struct omap_chan *c)
*/
if (c->desc) {
c->desc = NULL;
- omap_stop_dma(c->dma_ch);
+ /* Avoid stopping the dma twice */
+ if (!c->paused)
+ omap_stop_dma(c->dma_ch);
}

if (c->cyclic) {
c->cyclic = false;
+ c->paused = false;
omap_dma_unlink_lch(c->dma_ch, c->dma_ch);
}

@@ -487,14 +491,30 @@ static int omap_dma_terminate_all(struct omap_chan *c)

static int omap_dma_pause(struct omap_chan *c)
{
- /* FIXME: not supported by platform private API */
- return -EINVAL;
+ /* Pause/Resume only allowed with cyclic mode */
+ if (!c->cyclic)
+ return -EINVAL;
+
+ if (!c->paused) {
+ omap_stop_dma(c->dma_ch);
+ c->paused = true;
+ }
+
+ return 0;
}

static int omap_dma_resume(struct omap_chan *c)
{
- /* FIXME: not supported by platform private API */
- return -EINVAL;
+ /* Pause/Resume only allowed with cyclic mode */
+ if (!c->cyclic)
+ return -EINVAL;
+
+ if (c->paused) {
+ omap_start_dma(c->dma_ch);
+ c->paused = false;
+ }
+
+ return 0;
}

static int omap_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
--
1.7.12


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