i2c: at91: enable probe deferring on dma channel request

If dma controller is not probed, defer i2c probe.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 14 insertions, 11 deletions

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 8790f2332458..87e2f142ae6c 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -650,17 +650,17 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
         slave_config.dst_maxburst = 1;
         slave_config.device_fc = false;
 
-        dma->chan_tx = dma_request_slave_channel(dev->dev, "tx");
-        if (!dma->chan_tx) {
-                dev_err(dev->dev, "can't get a DMA channel for tx\n");
-                ret = -EBUSY;
+        dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx");
+        if (IS_ERR(dma->chan_tx)) {
+                ret = PTR_ERR(dma->chan_tx);
+                dma->chan_tx = NULL;
                 goto error;
         }
 
-        dma->chan_rx = dma_request_slave_channel(dev->dev, "rx");
-        if (!dma->chan_rx) {
-                dev_err(dev->dev, "can't get a DMA channel for rx\n");
-                ret = -EBUSY;
+        dma->chan_rx = dma_request_slave_channel_reason(dev->dev, "rx");
+        if (IS_ERR(dma->chan_rx)) {
+                ret = PTR_ERR(dma->chan_rx);
+                dma->chan_rx = NULL;
                 goto error;
         }
 
@@ -681,6 +681,7 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
         sg_init_table(&dma->sg, 1);
         dma->buf_mapped = false;
         dma->xfer_in_progress = false;
+        dev->use_dma = true;
 
         dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n",
                  dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
@@ -688,7 +689,8 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
         return ret;
 
 error:
-        dev_info(dev->dev, "can't use DMA\n");
+        if (ret != -EPROBE_DEFER)
+                dev_info(dev->dev, "can't use DMA, error %d\n", ret);
         if (dma->chan_rx)
                 dma_release_channel(dma->chan_rx);
         if (dma->chan_tx)
@@ -757,8 +759,9 @@ static int at91_twi_probe(struct platform_device *pdev)
         clk_prepare_enable(dev->clk);
 
         if (dev->dev->of_node) {
-                if (at91_twi_configure_dma(dev, phy_addr) == 0)
-                        dev->use_dma = true;
+                rc = at91_twi_configure_dma(dev, phy_addr);
+                if (rc == -EPROBE_DEFER)
+                        return rc;
         }
 
         rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",