driver: video: dc: Add check_ref_to_sync() in dc.

[linux-2.6.git] / drivers / video / tegra / dc / dc.c

diff --git a/drivers/video/tegra/dc/dc.c b/drivers/video/tegra/dc/dc.c
index 95d7ac19159a8a9010290125a10d979756f43289..f6488ad7699ee7e37ae58cf8b97d2e38c85e737e 100644 (file)
--- a/drivers/video/tegra/dc/dc.c
+++ b/drivers/video/tegra/dc/dc.c
@@ -1255,6 +1255,42 @@ static int calc_ref_to_sync(struct tegra_dc_mode *mode)
        return 0;
 }
 
+static bool check_ref_to_sync(struct tegra_dc_mode *mode)
+{
+       /* Constraint 1: H_REF_TO_SYNC + H_SYNC_WIDTH + H_BACK_PORCH > 11. */
+       if (mode->h_ref_to_sync + mode->h_sync_width + mode->h_back_porch <= 11)
+               return false;
+
+       /* Constraint 2: V_REF_TO_SYNC + V_SYNC_WIDTH + V_BACK_PORCH > 1. */
+       if (mode->v_ref_to_sync + mode->v_sync_width + mode->v_back_porch <= 1)
+               return false;
+
+       /* Constraint 3: V_FRONT_PORCH + V_SYNC_WIDTH + V_BACK_PORCH > 1
+        * (vertical blank). */
+       if (mode->v_front_porch + mode->v_sync_width + mode->v_back_porch <= 1)
+               return false;
+
+       /* Constraint 4: V_SYNC_WIDTH >= 1; H_SYNC_WIDTH >= 1. */
+       if (mode->v_sync_width < 1 || mode->h_sync_width < 1)
+               return false;
+
+       /* Constraint 5: V_REF_TO_SYNC >= 1; H_REF_TO_SYNC >= 0. */
+       if (mode->v_ref_to_sync < 1 || mode->h_ref_to_sync < 0)
+               return false;
+
+       /* Constraint 6: V_FRONT_PORT >= (V_REF_TO_SYNC + 1);
+        * H_FRONT_PORT >= (H_REF_TO_SYNC + 1). */
+       if (mode->v_front_porch < mode->v_ref_to_sync + 1 ||
+               mode->h_front_porch < mode->h_ref_to_sync + 1)
+               return false;
+
+       /* Constraint 7: H_DISP_ACTIVE >= 16; V_DISP_ACTIVE >= 16. */
+       if (mode->h_active < 16 || mode->v_active < 16)
+               return false;
+
+       return true;
+}
+
 #ifdef DEBUG
 /* return in 1000ths of a Hertz */
 static int calc_refresh(struct tegra_dc *dc, const struct tegra_dc_mode *m)
@@ -1417,6 +1453,11 @@ int tegra_dc_set_fb_mode(struct tegra_dc *dc,
                mode.h_ref_to_sync = 11;
                mode.v_ref_to_sync = 1;
        }
+       if (!check_ref_to_sync(&mode)) {
+               dev_err(&dc->ndev->dev,
+                               "Display timing doesn't meet restrictions.\n");
+               return -EINVAL;
+       }
        dev_info(&dc->ndev->dev, "Using mode %dx%d pclk=%d href=%d vref=%d\n",
                mode.h_active, mode.v_active, mode.pclk,
                mode.h_ref_to_sync, mode.v_ref_to_sync