OMAPDSS: DISPC: fix div by zero issue in overlay scaling

omapdrm doesn't always configure the overlays correctly, causing the
overlay setup functions to be called with zero timings. This leads to
division by zero error.

This happens, for example, when a HDMI cable is not connected, but a
user tries to setup a plane with scaling.

Fixing omapdrm is a big job, so for now let's check for the bad timings
in DISPC and return an error.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

diff --git a/drivers/video/fbdev/omap2/dss/dispc.c b/drivers/video/fbdev/omap2/dss/dispc.c
index 8805266a52f411b7a27f431ca7c97b26b897a8ef..1123111d394023f58c3b1e29d876f4d45d5aed77 100644 (file)
--- a/drivers/video/fbdev/omap2/dss/dispc.c
+++ b/drivers/video/fbdev/omap2/dss/dispc.c
@@ -2322,6 +2322,11 @@ static int dispc_ovl_calc_scaling(unsigned long pclk, unsigned long lclk,
        if (width == out_width && height == out_height)
                return 0;
 
+       if (pclk == 0 || mgr_timings->pixelclock == 0) {
+               DSSERR("cannot calculate scaling settings: pclk is zero\n");
+               return -EINVAL;
+       }
+
        if ((caps & OMAP_DSS_OVL_CAP_SCALE) == 0)
                return -EINVAL;