Intel FB: force even line count in interlaced mode

Intel FB: the chip adds two halflines automatically in interlaced mode,
force even line count for the right timings.

Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: <sylvain.meyer@worldonline.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/video/intelfb/intelfbhw.c b/drivers/video/intelfb/intelfbhw.c
index 270f6552603c..a02ee24f3668 100644
--- a/drivers/video/intelfb/intelfbhw.c
+++ b/drivers/video/intelfb/intelfbhw.c
@@ -317,6 +317,14 @@ int intelfbhw_validate_mode(struct intelfb_info *dinfo,
                         var->yres, VACTIVE_MASK + 1);
                 return 1;
         }
+        if (var->xres < 4) {
+                WRN_MSG("X resolution too small (%d vs 4).\n", var->xres);
+                return 1;
+        }
+        if (var->yres < 4) {
+                WRN_MSG("Y resolution too small (%d vs 4).\n", var->yres);
+                return 1;
+        }
 
         /* Check for doublescan modes. */
         if (var->vmode & FB_VMODE_DOUBLE) {
@@ -324,6 +332,11 @@ int intelfbhw_validate_mode(struct intelfb_info *dinfo,
                 return 1;
         }
 
+        if ((var->vmode & FB_VMODE_INTERLACED) && (var->yres & 1)) {
+                WRN_MSG("Odd number of lines in interlaced mode\n");
+                return 1;
+        }
+
         /* Check if clock is OK. */
         tmp = 1000000000 / var->pixclock;
         if (tmp < MIN_CLOCK) {
@@ -1127,6 +1140,8 @@ int intelfbhw_mode_to_hw(struct intelfb_info *dinfo,
                 hblank_end);
 
         vactive = var->yres;
+        if (var->vmode & FB_VMODE_INTERLACED)
+                vactive--; /* the chip adds 2 halflines automatically */
         vsync_start = vactive + var->lower_margin;
         vsync_end = vsync_start + var->vsync_len;
         vtotal = vsync_end + var->upper_margin;