[PATCH 4.9 047/167] drm/msm/dsi: fix error checks and return values for DSI xmit functions

Greg Kroah-Hartman
2022-06-13T10:19:28Z

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

[ Upstream commit f0e7e9ed379c012c4d6b09a09b868accc426223c ]

As noticed by Dan ([1] an the followup thread) there are multiple issues
with the return values for MSM DSI command transmission callback. In
the error case it can easily return a positive value when it should
have returned a proper error code.

This commits attempts to fix these issues both in TX and in RX paths.

[1]: https://lore.kernel.org/linux-arm-msm/20211001123617.GH2283@kili/

Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/480501/
Link: https://lore.kernel.org/r/20220401231104.967193-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/msm/dsi/dsi_host.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 246336a9f47d..bea4969900ab 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -1240,10 +1240,10 @@ static int dsi_cmds2buf_tx(struct msm_dsi_host *msm_host,
dsi_get_bpp(msm_host->format) / 8;

len = dsi_cmd_dma_add(msm_host, msg);
- if (!len) {
+ if (len < 0) {
pr_err("%s: failed to add cmd type = 0x%x\n",
__func__, msg->type);
- return -EINVAL;
+ return len;
}

/* for video mode, do not send cmds more than
@@ -1262,10 +1262,14 @@ static int dsi_cmds2buf_tx(struct msm_dsi_host *msm_host,
}

ret = dsi_cmd_dma_tx(msm_host, len);
- if (ret < len) {
- pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, len=%d\n",
- __func__, msg->type, (*(u8 *)(msg->tx_buf)), len);
- return -ECOMM;
+ if (ret < 0) {
+ pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, len=%d, ret=%d\n",
+ __func__, msg->type, (*(u8 *)(msg->tx_buf)), len, ret);
+ return ret;
+ } else if (ret < len) {
+ pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, ret=%d len=%d\n",
+ __func__, msg->type, (*(u8 *)(msg->tx_buf)), ret, len);
+ return -EIO;
}

return len;
@@ -1979,9 +1983,12 @@ 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) {
pr_err("%s: Read cmd Tx failed, %d\n", __func__, ret);
return ret;
+ } else if (ret < msg->tx_len) {
+ pr_err("%s: Read cmd Tx failed, too short: %d\n", __func__, ret);
+ return -ECOMM;
}

/*
--
2.35.1