[PATCH 2/2] i2c: imx: return -ENXIO at once when a DMA write is not acknowledged

[Mehmet Fide <mehmet.fide@gmail.com>]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

When the address of a DMA write is not acknowledged the controller
raises its interrupt and no DMA request, so i2c_imx_dma_write() blocks
for DMA_TIMEOUT (1 s) and returns -ETIMEDOUT, where the interrupt driven
write returns -ENXIO.

Let the interrupt handler end the wait when it sees a missing
acknowledge during a DMA write, and return -ENXIO. No interrupt arrives
while the bytes of a DMA write are acknowledged, so that path does not
change.

Fixes: ce1a78840ff7 ("i2c: imx: add DMA support for freescale i2c driver")
Cc: stable@vger.kernel.org
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
 drivers/i2c/busses/i2c-imx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 1987a0fd8132..09934f3b13ef 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1108,6 +1108,9 @@ static irqreturn_t i2c_imx_master_isr(struct imx_i2c_struct *i2c_imx, unsigned i
 	switch (i2c_imx->state) {
 	case IMX_I2C_STATE_DMA:
 		i2c_imx->i2csr = status;
+		if ((status & I2SR_RXAK) &&
+		    i2c_imx->dma->dma_transfer_dir == DMA_MEM_TO_DEV)
+			complete(&i2c_imx->dma->cmd_complete);
 		wake_up(&i2c_imx->queue);
 		break;
 
@@ -1225,6 +1228,11 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
 		return -ETIMEDOUT;
 	}
 
+	if (i2c_imx->i2csr & I2SR_RXAK) {
+		dmaengine_terminate_sync(dma->chan_using);
+		return -ENXIO;
+	}
+
 	/* Waiting for transfer complete. */
 	while (1) {
 		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
-- 
2.56.0