drm/amd/display: Check returns from drm_dp_dpcd_write

[WHAT & HOW]
drm_dp_dpcd_write() returns negative error on failure and thus returned
values need to be checked.

This fixes 3 UNUSED_VALUE issues reported by Coverity.

Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 6923184..8eaf292 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -643,6 +643,8 @@ static bool execute_synaptics_rc_command(struct drm_dp_aux *aux,
                // write rc data
                memmove(rc_data, data, length);
                ret = drm_dp_dpcd_write(aux, SYNAPTICS_RC_DATA, rc_data, sizeof(rc_data));
+               if (ret < 0)
+                       goto err;
        }
 
        // write rc offset
@@ -651,20 +653,21 @@ static bool execute_synaptics_rc_command(struct drm_dp_aux *aux,
        rc_offset[2] = (unsigned char) (offset >> 16) & 0xFF;
        rc_offset[3] = (unsigned char) (offset >> 24) & 0xFF;
        ret = drm_dp_dpcd_write(aux, SYNAPTICS_RC_OFFSET, rc_offset, sizeof(rc_offset));
+       if (ret < 0)
+               goto err;
 
        // write rc length
        rc_length[0] = (unsigned char) length & 0xFF;
        rc_length[1] = (unsigned char) (length >> 8) & 0xFF;
        ret = drm_dp_dpcd_write(aux, SYNAPTICS_RC_LENGTH, rc_length, sizeof(rc_length));
+       if (ret < 0)
+               goto err;
 
        // write rc cmd
        rc_cmd = cmd | 0x80;
        ret = drm_dp_dpcd_write(aux, SYNAPTICS_RC_COMMAND, &rc_cmd, sizeof(rc_cmd));
-
-       if (ret < 0) {
-               DRM_ERROR("%s: write cmd ..., err = %d\n",  __func__, ret);
-               return false;
-       }
+       if (ret < 0)
+               goto err;
 
        // poll until active is 0
        for (i = 0; i < 10; i++) {
@@ -687,6 +690,10 @@ static bool execute_synaptics_rc_command(struct drm_dp_aux *aux,
        drm_dbg_dp(aux->drm_dev, "success = %d\n", success);
 
        return success;
+
+err:
+       DRM_ERROR("%s: write cmd ..., err = %d\n",  __func__, ret);
+       return false;
 }
 
 static void apply_synaptics_fifo_reset_wa(struct drm_dp_aux *aux)