drm/tegra: Split DC_CMD_STATE_CONTROL register write

The Tegra TRM says that the ACT_REQ and UPDATE fields cannot be
programmed at the same time so they are updated in two consecutive
writes instead.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index c5d825f..2086400 100644 (file)
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -689,9 +689,10 @@ static void tegra_crtc_commit(struct drm_crtc *crtc)
        struct tegra_dc *dc = to_tegra_dc(crtc);
        unsigned long value;
 
-       value = GENERAL_ACT_REQ | WIN_A_ACT_REQ |
-               GENERAL_UPDATE | WIN_A_UPDATE;
+       value = GENERAL_UPDATE | WIN_A_UPDATE;
+       tegra_dc_writel(dc, value, DC_CMD_STATE_CONTROL);
 
+       value = GENERAL_ACT_REQ | WIN_A_ACT_REQ;
        tegra_dc_writel(dc, value, DC_CMD_STATE_CONTROL);
 
        drm_vblank_post_modeset(crtc->dev, dc->pipe);