dmaengine i.MX SDMA: reserve channel 0 by not registering it
We need channel 0 of the sdma engine for internal purposes. We
accomplished this by calling dma_request_channel() in the probe
function. This does not work when multiple dma engines are
present which is the case when IPU support for i.MX31/35 is
compiled in. So instead of registering channel 0 and reserving
it afterwards simply do not register it in the first place.
With this the dmaengine channel counting does not match sdma
channel counting anymore, so we have to use sdma channel counting
in the driver.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index eb25068..1eb3f00 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -230,7 +230,7 @@
* struct sdma_channel - housekeeping for a SDMA channel
*
* @sdma pointer to the SDMA engine for this channel
- * @channel the channel number, matches dmaengine chan_id
+ * @channel the channel number, matches dmaengine chan_id + 1
* @direction transfer type. Needed for setting SDMA script
* @peripheral_type Peripheral type. Needed for setting SDMA script
* @event_id0 aka dma request line
@@ -799,7 +799,7 @@
cookie = sdma_assign_cookie(sdmac);
- sdma_enable_channel(sdma, tx->chan->chan_id);
+ sdma_enable_channel(sdma, sdmac->channel);
spin_unlock_irq(&sdmac->lock);
@@ -812,10 +812,6 @@
struct imx_dma_data *data = chan->private;
int prio, ret;
- /* No need to execute this for internal channel 0 */
- if (chan->chan_id == 0)
- return 0;
-
if (!data)
return -EINVAL;
@@ -880,7 +876,7 @@
struct sdma_channel *sdmac = to_sdma_chan(chan);
struct sdma_engine *sdma = sdmac->sdma;
int ret, i, count;
- int channel = chan->chan_id;
+ int channel = sdmac->channel;
struct scatterlist *sg;
if (sdmac->status == DMA_IN_PROGRESS)
@@ -978,7 +974,7 @@
struct sdma_channel *sdmac = to_sdma_chan(chan);
struct sdma_engine *sdma = sdmac->sdma;
int num_periods = buf_len / period_len;
- int channel = chan->chan_id;
+ int channel = sdmac->channel;
int ret, i = 0, buf = 0;
dev_dbg(sdma->dev, "%s channel: %d\n", __func__, channel);
@@ -1252,7 +1248,6 @@
struct resource *iores;
struct sdma_platform_data *pdata = pdev->dev.platform_data;
int i;
- dma_cap_mask_t mask;
struct sdma_engine *sdma;
sdma = kzalloc(sizeof(*sdma), GFP_KERNEL);
@@ -1309,8 +1304,14 @@
sdmac->chan.device = &sdma->dma_device;
sdmac->channel = i;
- /* Add the channel to the DMAC list */
- list_add_tail(&sdmac->chan.device_node, &sdma->dma_device.channels);
+ /*
+ * Add the channel to the DMAC list. Do not add channel 0 though
+ * because we need it internally in the SDMA driver. This also means
+ * that channel 0 in dmaengine counting matches sdma channel 1.
+ */
+ if (i)
+ list_add_tail(&sdmac->chan.device_node,
+ &sdma->dma_device.channels);
}
ret = sdma_init(sdma);
@@ -1340,13 +1341,6 @@
goto err_init;
}
- /* request channel 0. This is an internal control channel
- * to the SDMA engine and not available to clients.
- */
- dma_cap_zero(mask);
- dma_cap_set(DMA_SLAVE, mask);
- dma_request_channel(mask, NULL, NULL);
-
dev_info(sdma->dev, "initialized\n");
return 0;