[PATCH 3/4] i2c: stm32f7: stop dma transfer in case of NACK

[Alain Volmat]

In case of receiving a NACK, the dma transfer should be stopped
to avoid feeding data into the FIFO.
Also ensure to properly return the proper error code and avoid
waiting for the end of the dma completion in case of
error happening during the transmission.

Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")

Signed-off-by: Alain Volmat <alain.volmat at foss.st.com>
---
 drivers/i2c/busses/i2c-stm32f7.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index ad3459a3bc5e..50d5ae81d227 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1493,6 +1493,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 {
 	struct stm32f7_i2c_dev *i2c_dev = data;
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	void __iomem *base = i2c_dev->base;
 	u32 status, mask;
 	int ret = IRQ_HANDLED;
@@ -1518,6 +1519,10 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		dev_dbg(i2c_dev->dev, "<%s>: Receive NACK (addr %x)\n",
 			__func__, f7_msg->addr);
 		writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
+		if (i2c_dev->use_dma) {
+			stm32f7_i2c_disable_dma_req(i2c_dev);
+			dmaengine_terminate_all(dma->chan_using);
+		}
 		f7_msg->result = -ENXIO;
 	}
 
@@ -1533,7 +1538,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		/* Clear STOP flag */
 		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
 
-		if (i2c_dev->use_dma) {
+		if (i2c_dev->use_dma && !f7_msg->result) {
 			ret = IRQ_WAKE_THREAD;
 		} else {
 			i2c_dev->master_mode = false;
@@ -1546,7 +1551,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		if (f7_msg->stop) {
 			mask = STM32F7_I2C_CR2_STOP;
 			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
-		} else if (i2c_dev->use_dma) {
+		} else if (i2c_dev->use_dma && !f7_msg->result) {
 			ret = IRQ_WAKE_THREAD;
 		} else if (f7_msg->smbus) {
 			stm32f7_i2c_smbus_rep_start(i2c_dev);
-- 
2.25.1