i2c: qcom-geni: Fix GPI DMA buffer sync-back

Fix i2c transfers using GPI DMA mode for all message types that do not set
the I2C_M_DMA_SAFE flag (e.g. SMBus "read byte").

In this case a bounce buffer is returned by i2c_get_dma_safe_msg_buf(),
and it has to synced back to the message after the transfer is done.

Add missing assignment of dma buffer in geni_i2c_gpi().

Set xferred in i2c_put_dma_safe_msg_buf() to true in case of no error to
ensure the sync-back of this dma buffer to the message.

Fixes: d8703554 ("i2c: qcom-geni: Add support for GPI DMA")
Signed-off-by: Robin Reckmann <robin.reckmann@gmail.com>
Tested-by: Luca Weiss <luca.weiss@fairphone.com>
Tested-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-qcom-geni.c

@@ -494,12 +494,12 @@ static void geni_i2c_gpi_unmap(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 {
 	if (tx_buf) {
 		dma_unmap_single(gi2c->se.dev->parent, tx_addr, msg->len, DMA_TO_DEVICE);
-		i2c_put_dma_safe_msg_buf(tx_buf, msg, false);
+		i2c_put_dma_safe_msg_buf(tx_buf, msg, !gi2c->err);
 	}
 
 	if (rx_buf) {
 		dma_unmap_single(gi2c->se.dev->parent, rx_addr, msg->len, DMA_FROM_DEVICE);
-		i2c_put_dma_safe_msg_buf(rx_buf, msg, false);
+		i2c_put_dma_safe_msg_buf(rx_buf, msg, !gi2c->err);
 	}
 }
 
@@ -563,6 +563,7 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 	desc->callback_param = gi2c;
 
 	dmaengine_submit(desc);
+	*buf = dma_buf;
 	*dma_addr_p = addr;
 
 	return 0;