vsync length.
+----------+---------------------------------------------+----------+-------+
- | | ^ | | |
+ | | ↑ | | |
| | |upper_margin | | |
- | | ¥ | | |
+ | | ↓ | | |
+----------###############################################----------+-------+
- | # ^ # | |
+ | # ↑ # | |
| # | # | |
| # | # | |
| # | # | |
| # | # | |
| # | # | |
| # | # | |
- | # ¥ # | |
+ | # ↓ # | |
+----------###############################################----------+-------+
- | | ^ | | |
+ | | ↑ | | |
| | |lower_margin | | |
- | | ¥ | | |
+ | | ↓ | | |
+----------+---------------------------------------------+----------+-------+
- | | ^ | | |
+ | | ↑ | | |
| | |vsync_len | | |
- | | ¥ | | |
+ | | ↓ | | |
+----------+---------------------------------------------+----------+-------+
The frame buffer device expects all horizontal timings in number of dotclocks