On 01-03-21, 14:41, Jie Deng wrote:

quoted

+/**
+ * struct virtio_i2c_req - the virtio I2C request structure
+ * @out_hdr: the OUT header of the virtio I2C message
+ * @write_buf: contains one I2C segment being written to the device
+ * @read_buf: contains one I2C segment being read from the device
+ * @in_hdr: the IN header of the virtio I2C message
+ */
+struct virtio_i2c_req {
+	struct virtio_i2c_out_hdr out_hdr;
+	u8 *write_buf;
+	u8 *read_buf;
+	struct virtio_i2c_in_hdr in_hdr;
+};

I am not able to appreciate the use of write/read bufs here as we
aren't trying to read/write data in the same transaction. Why do we
have two bufs here as well as in specs ?

What about this on top of your patch ?

---
  drivers/i2c/busses/i2c-virtio.c | 31 +++++++++++--------------------
  include/uapi/linux/virtio_i2c.h |  3 +--
  2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
index 8c8bc9545418..e71ab1d2c83f 100644
--- a/drivers/i2c/busses/i2c-virtio.c
+++ b/drivers/i2c/busses/i2c-virtio.c

@@ -67,14 +67,13 @@ static int virtio_i2c_send_reqs(struct virtqueue *vq,
  		if (!buf)
  			break;
  
+		reqs[i].buf = buf;
+		sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
+
  		if (msgs[i].flags & I2C_M_RD) {
-			reqs[i].read_buf = buf;
-			sg_init_one(&msg_buf, reqs[i].read_buf, msgs[i].len);
  			sgs[outcnt + incnt++] = &msg_buf;
  		} else {
-			reqs[i].write_buf = buf;
-			memcpy(reqs[i].write_buf, msgs[i].buf, msgs[i].len);
-			sg_init_one(&msg_buf, reqs[i].write_buf, msgs[i].len);
+			memcpy(reqs[i].buf, msgs[i].buf, msgs[i].len);
  			sgs[outcnt++] = &msg_buf;
  		}
  

@@ -84,13 +83,8 @@ static int virtio_i2c_send_reqs(struct virtqueue *vq,
  		err = virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i], GFP_KERNEL);
  		if (err < 0) {
  			pr_err("failed to add msg[%d] to virtqueue.\n", i);
-			if (msgs[i].flags & I2C_M_RD) {
-				kfree(reqs[i].read_buf);
-				reqs[i].read_buf = NULL;
-			} else {
-				kfree(reqs[i].write_buf);
-				reqs[i].write_buf = NULL;
-			}
+			kfree(reqs[i].buf);
+			reqs[i].buf = NULL;
  			break;
  		}
  	}

@@ -118,14 +112,11 @@ static int virtio_i2c_complete_reqs(struct virtqueue *vq,
  			break;
  		}
  
-		if (msgs[i].flags & I2C_M_RD) {
-			memcpy(msgs[i].buf, req->read_buf, msgs[i].len);
-			kfree(req->read_buf);
-			req->read_buf = NULL;
-		} else {
-			kfree(req->write_buf);
-			req->write_buf = NULL;
-		}
+		if (msgs[i].flags & I2C_M_RD)
+			memcpy(msgs[i].buf, req->buf, msgs[i].len);
+
+		kfree(req->buf);
+		req->buf = NULL;
  	}
  
  	return i;

diff --git a/include/uapi/linux/virtio_i2c.h b/include/uapi/linux/virtio_i2c.h
index 92febf0c527e..61f0086ac75b 100644
--- a/include/uapi/linux/virtio_i2c.h
+++ b/include/uapi/linux/virtio_i2c.h

@@ -48,8 +48,7 @@ struct virtio_i2c_in_hdr {
   */
  struct virtio_i2c_req {
  	struct virtio_i2c_out_hdr out_hdr;
-	u8 *write_buf;
-	u8 *read_buf;
+	u8 *buf;
  	struct virtio_i2c_in_hdr in_hdr;
  };