drm/tilcdc: Clear bits of register we're going to set.

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / tilcdc / tilcdc_crtc.c

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 43120fa3b6e9eba3e474bcda3b75f515c1a1a570..7418dcd986d3f50f48f33d56b703cf8dc82c4be9 100644 (file)
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -299,6 +299,8 @@ static int tilcdc_crtc_mode_set(struct drm_crtc *crtc,
         * a value of 0 as 1
         */
        if (priv->rev == 2) {
+               /* clear bits we're going to set */
+               reg &= ~0x78000033;
                reg |= ((hfp-1) & 0x300) >> 8;
                reg |= ((hbp-1) & 0x300) >> 4;
                reg |= ((hsw-1) & 0x3c0) << 21;