drm/amdgpu: make sure vertical front porch is at least 1
hw doesn't like a 0 value.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
index 1e0bba2..1cd6de5 100644
--- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
@@ -298,6 +298,10 @@
&& (mode->crtc_vsync_start < (mode->crtc_vdisplay + 2)))
adjusted_mode->crtc_vsync_start = adjusted_mode->crtc_vdisplay + 2;
+ /* vertical FP must be at least 1 */
+ if (mode->crtc_vsync_start == mode->crtc_vdisplay)
+ adjusted_mode->crtc_vsync_start++;
+
/* get the native mode for scaling */
if (amdgpu_encoder->active_device & (ATOM_DEVICE_LCD_SUPPORT))
amdgpu_panel_mode_fixup(encoder, adjusted_mode);