From mboxrd@z Thu Jan 1 00:00:00 1970 From: peter.ujfalusi@ti.com (Peter Ujfalusi) Date: Fri, 14 Sep 2012 15:05:45 +0300 Subject: [PATCH v3 02/15] dmaengine: omap: Add support for pause/resume in cyclic dma mode In-Reply-To: <1347624358-25582-1-git-send-email-peter.ujfalusi@ti.com> References: <1347624358-25582-1-git-send-email-peter.ujfalusi@ti.com> Message-ID: <1347624358-25582-3-git-send-email-peter.ujfalusi@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 CC: Russell King --- 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