[PATCH 3/3] drm/msm/dsi: fix signedness bug in msm_dsi_host_cmd_rx()

[Dan Carpenter]

The "msg->tx_len" variable is type size_t so if dsi_cmds2buf_tx()
returns a negative error code that it type promoted to a high positive
value and treat as a success.  The second problem with this code is
that it can return meaningless positive values on error.

Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index c86b5090fae6..42073a562072 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -2133,8 +2133,10 @@ int msm_dsi_host_cmd_rx(struct mipi_dsi_host *host,
 		}
 
 		ret = dsi_cmds2buf_tx(msm_host, msg);
-		if (ret < msg->tx_len) {
+		if (ret < 0 || ret < msg->tx_len) {
 			pr_err("%s: Read cmd Tx failed, %d\n", __func__, ret);
+			if (ret >= 0)
+				ret = -EIO;
 			return ret;
 		}
 
-- 
2.20.1