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 1e0bba29e16796f97c8eee38fc9d3100c405f6bc..1cd6de575305aa3f657fa1a7f5a70232b272d739 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
@@ -298,6 +298,10 @@ bool amdgpu_atombios_encoder_mode_fixup(struct drm_encoder *encoder,
            && (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);