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>

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>
Sascha Hauer
1 parent 7214a8b14f
Showing 1 changed file with 12 additions and 18 deletions Side-by-side Diff
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);
@@ -1339,13 +1340,6 @@
 		dev_err(&pdev->dev, "unable to register\n");
 		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");
...	...	@@ -230,7 +230,7 @@
230	230	* struct sdma_channel - housekeeping for a SDMA channel
231	231	*
232	232	* @sdma pointer to the SDMA engine for this channel
233		- * @channel the channel number, matches dmaengine chan_id
	233	+ * @channel the channel number, matches dmaengine chan_id + 1
234	234	* @direction transfer type. Needed for setting SDMA script
235	235	* @peripheral_type Peripheral type. Needed for setting SDMA script
236	236	* @event_id0 aka dma request line
...	...	@@ -799,7 +799,7 @@
799	799
800	800	cookie = sdma_assign_cookie(sdmac);
801	801
802		- sdma_enable_channel(sdma, tx->chan->chan_id);
	802	+ sdma_enable_channel(sdma, sdmac->channel);
803	803
804	804	spin_unlock_irq(&sdmac->lock);
805	805
...	...	@@ -812,10 +812,6 @@
812	812	struct imx_dma_data *data = chan->private;
813	813	int prio, ret;
814	814
815		- /* No need to execute this for internal channel 0 */
816		- if (chan->chan_id == 0)
817		- return 0;
818		-
819	815	if (!data)
820	816	return -EINVAL;
821	817
...	...	@@ -880,7 +876,7 @@
880	876	struct sdma_channel *sdmac = to_sdma_chan(chan);
881	877	struct sdma_engine *sdma = sdmac->sdma;
882	878	int ret, i, count;
883		- int channel = chan->chan_id;
	879	+ int channel = sdmac->channel;
884	880	struct scatterlist *sg;
885	881
886	882	if (sdmac->status == DMA_IN_PROGRESS)
...	...	@@ -978,7 +974,7 @@
978	974	struct sdma_channel *sdmac = to_sdma_chan(chan);
979	975	struct sdma_engine *sdma = sdmac->sdma;
980	976	int num_periods = buf_len / period_len;
981		- int channel = chan->chan_id;
	977	+ int channel = sdmac->channel;
982	978	int ret, i = 0, buf = 0;
983	979
984	980	dev_dbg(sdma->dev, "%s channel: %d\n", __func__, channel);
...	...	@@ -1252,7 +1248,6 @@
1252	1248	struct resource *iores;
1253	1249	struct sdma_platform_data *pdata = pdev->dev.platform_data;
1254	1250	int i;
1255		- dma_cap_mask_t mask;
1256	1251	struct sdma_engine *sdma;
1257	1252
1258	1253	sdma = kzalloc(sizeof(*sdma), GFP_KERNEL);
...	...	@@ -1309,8 +1304,14 @@
1309	1304	sdmac->chan.device = &sdma->dma_device;
1310	1305	sdmac->channel = i;
1311	1306
1312		- /* Add the channel to the DMAC list */
1313		- list_add_tail(&sdmac->chan.device_node, &sdma->dma_device.channels);
	1307	+ /*
	1308	+ * Add the channel to the DMAC list. Do not add channel 0 though
	1309	+ * because we need it internally in the SDMA driver. This also means
	1310	+ * that channel 0 in dmaengine counting matches sdma channel 1.
	1311	+ */
	1312	+ if (i)
	1313	+ list_add_tail(&sdmac->chan.device_node,
	1314	+ &sdma->dma_device.channels);
1314	1315	}
1315	1316
1316	1317	ret = sdma_init(sdma);
...	...	@@ -1339,13 +1340,6 @@
1339	1340	dev_err(&pdev->dev, "unable to register\n");
1340	1341	goto err_init;
1341	1342	}
1342		-
1343		- /* request channel 0. This is an internal control channel
1344		- * to the SDMA engine and not available to clients.
1345		- */
1346		- dma_cap_zero(mask);
1347		- dma_cap_set(DMA_SLAVE, mask);
1348		- dma_request_channel(mask, NULL, NULL);
1349	1343
1350	1344	dev_info(sdma->dev, "initialized\n");
1351	1345