gma500: Prevent endless loop in panel power up sequence

Some devices don't have a panel connected to LVDS and thus will never power up.
This patch checks the power sequence progress bits in PP_STATUS to prevent an
endless loop on such devices.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/gpu/drm/gma500/psb_lid.c b/drivers/gpu/drm/gma500/psb_lid.c
index 7ff8bb2bdc23..1d2ebb5e530f 100644
--- a/drivers/gpu/drm/gma500/psb_lid.c
+++ b/drivers/gpu/drm/gma500/psb_lid.c
@@ -40,10 +40,16 @@ static void psb_lid_timer_func(unsigned long data)
                 REG_WRITE(PP_CONTROL, REG_READ(PP_CONTROL) | POWER_TARGET_ON);
                 do {
                         pp_status = REG_READ(PP_STATUS);
-                } while ((pp_status & PP_ON) == 0);
+                } while ((pp_status & PP_ON) == 0 &&
+                         (pp_status & PP_SEQUENCE_MASK) != 0);
 
-                /*FIXME: should be backlight level before*/
-                psb_intel_lvds_set_brightness(dev, 100);
+                if (REG_READ(PP_STATUS) & PP_ON) {
+                        /*FIXME: should be backlight level before*/
+                        psb_intel_lvds_set_brightness(dev, 100);
+                } else {
+                        DRM_DEBUG("LVDS panel never powered up");
+                        return;
+                }
         } else {
                 psb_intel_lvds_set_brightness(dev, 0);