dmaengine: omap: Add support for pause/resume in cyclic dma mode

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>
Acked-by: Vinod Koul <vinod.koul@linux.intel.com>
Tested-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index b77a40d..71d7869 100644 (file)
--- 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,