Allocate only one DMA channel for I2C and share it for both Tx and Rx.
Since I2C supports only half duplex, there is no impact on perf with
this.
Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
---
v1->v2: Remove WARN_ON for DMA channel mismatch. There is only one
channel in use with this change.
drivers/i2c/busses/i2c-tegra.c | 54 ++++++++++------------------------
1 file changed, 15 insertions(+), 39 deletions(-)
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6aab84c8d22b..f52b835f1700 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -248,8 +248,7 @@ struct tegra_i2c_hw_feature {
* @msg_read: indicates that the transfer is a read access
* @timings: i2c timings information like bus frequency
* @multimaster_mode: indicates that I2C controller is in multi-master mode
- * @tx_dma_chan: DMA transmit channel
- * @rx_dma_chan: DMA receive channel
+ * @dma_chan: DMA channel
* @dma_phys: handle to DMA resources
* @dma_buf: pointer to allocated DMA buffer
* @dma_buf_size: DMA buffer size
@@ -281,8 +280,7 @@ struct tegra_i2c_dev {
u8 *msg_buf;
struct completion dma_complete;
- struct dma_chan *tx_dma_chan;
- struct dma_chan *rx_dma_chan;
+ struct dma_chan *dma_chan;
unsigned int dma_buf_size;
struct device *dma_dev;
dma_addr_t dma_phys;
@@ -398,7 +396,7 @@ static int tegra_i2c_dma_submit(struct tegra_i2c_dev *i2c_dev, size_t len)
reinit_completion(&i2c_dev->dma_complete);
dir = i2c_dev->msg_read ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV;
- chan = i2c_dev->msg_read ? i2c_dev->rx_dma_chan : i2c_dev->tx_dma_chan;
+ chan = i2c_dev->dma_chan;
dma_desc = dmaengine_prep_slave_single(chan, i2c_dev->dma_phys,
len, dir, DMA_PREP_INTERRUPT |
@@ -426,14 +424,9 @@ static void tegra_i2c_release_dma(struct tegra_i2c_dev *i2c_dev)
i2c_dev->dma_buf = NULL;
}
- if (i2c_dev->tx_dma_chan) {
- dma_release_channel(i2c_dev->tx_dma_chan);
- i2c_dev->tx_dma_chan = NULL;
- }
-
- if (i2c_dev->rx_dma_chan) {
- dma_release_channel(i2c_dev->rx_dma_chan);
- i2c_dev->rx_dma_chan = NULL;
+ if (i2c_dev->dma_chan) {
+ dma_release_channel(i2c_dev->dma_chan);
+ i2c_dev->dma_chan = NULL;
}
}
@@ -457,25 +450,18 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
return 0;
}
- chan = dma_request_chan(i2c_dev->dev, "rx");
- if (IS_ERR(chan)) {
- err = PTR_ERR(chan);
- goto err_out;
- }
-
- i2c_dev->rx_dma_chan = chan;
-
+ /* The same channel will be used for both Rx and Tx.
+ * Keeping the name as tx for backward compatibility with
+ * existing devicetrees.
+ */
chan = dma_request_chan(i2c_dev->dev, "tx");
if (IS_ERR(chan)) {
err = PTR_ERR(chan);
goto err_out;
}
- i2c_dev->tx_dma_chan = chan;
-
- WARN_ON(i2c_dev->tx_dma_chan->device != i2c_dev->rx_dma_chan->device);
+ i2c_dev->dma_chan = chan;
i2c_dev->dma_dev = chan->device->dev;
-
i2c_dev->dma_buf_size = i2c_dev->hw->quirks->max_write_len +
I2C_PACKET_HEADER_SIZE;
@@ -974,11 +960,7 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);
if (i2c_dev->dma_mode) {
- if (i2c_dev->msg_read)
- dmaengine_terminate_async(i2c_dev->rx_dma_chan);
- else
- dmaengine_terminate_async(i2c_dev->tx_dma_chan);
-
+ dmaengine_terminate_async(i2c_dev->dma_chan);
complete(&i2c_dev->dma_complete);
}
@@ -1008,8 +990,8 @@ static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
else
dma_burst = 8;
+ chan = i2c_dev->dma_chan;
if (i2c_dev->msg_read) {
- chan = i2c_dev->rx_dma_chan;
reg_offset = tegra_i2c_reg_addr(i2c_dev, I2C_RX_FIFO);
slv_config.src_addr = i2c_dev->base_phys + reg_offset;
@@ -1021,7 +1003,6 @@ static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
else
val = I2C_FIFO_CONTROL_RX_TRIG(dma_burst);
} else {
- chan = i2c_dev->tx_dma_chan;
reg_offset = tegra_i2c_reg_addr(i2c_dev, I2C_TX_FIFO);
slv_config.dst_addr = i2c_dev->base_phys + reg_offset;
@@ -1333,13 +1314,8 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
* performs synchronization after the transfer's termination
* and we want to get a completion if transfer succeeded.
*/
- dmaengine_synchronize(i2c_dev->msg_read ?
- i2c_dev->rx_dma_chan :
- i2c_dev->tx_dma_chan);
-
- dmaengine_terminate_sync(i2c_dev->msg_read ?
- i2c_dev->rx_dma_chan :
- i2c_dev->tx_dma_chan);
+ dmaengine_synchronize(i2c_dev->dma_chan);
+ dmaengine_terminate_sync(i2c_dev->dma_chan);
if (!time_left && !completion_done(&i2c_dev->dma_complete)) {
dev_err(i2c_dev->dev, "DMA transfer timed out\n");
--
2.17.1
