drm/radeon: make sure vertical front porch is at least 1

[ Upstream commit 3104b8128d4d646a574ed9d5b17c7d10752cd70b ]

hw doesn't like a 0 value.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index 01701105653d2a613eb6b49c3e7b1f723e8907cd..07dd3523425aeea9ed40e48c080eb8eb19df4a25 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -308,6 +308,10 @@ static bool radeon_atom_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 (radeon_encoder->active_device & (ATOM_DEVICE_LCD_SUPPORT)) {
                radeon_panel_mode_fixup(encoder, adjusted_mode);