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,