integrate general improvements from Ossc Pro

* OSD timing optimizations and cursor color selection
* flash robustness fixes

scripts/qsys.patch

@@ -0,0 +1,13 @@
+--- sys/synthesis/submodules/sys_master_0.v	2025-07-25 10:15:46.708247405 +0300
++++ sys/synthesis/submodules/sys_master_0.v	2025-07-25 10:15:54.937804924 +0300
+@@ -156,9 +156,9 @@
+ 
+ 	altera_avalon_sc_fifo #(
+ 		.SYMBOLS_PER_BEAT    (1),
+ 		.BITS_PER_SYMBOL     (8),
+-		.FIFO_DEPTH          (64),
++		.FIFO_DEPTH          (1024),
+ 		.CHANNEL_WIDTH       (0),
+ 		.ERROR_WIDTH         (0),
+ 		.USE_PACKETS         (0),
+ 		.USE_FILL_LEVEL      (0),

scripts/rv-reprogram.tcl

@@ -64,21 +64,24 @@ for {set i 0} {$i<$num_sectors} {incr i} {
 }
 
 puts "Writing flash"
-# writes garbage and occasionally hangs (bug in generic serial flash IF?)
+# JTAG to Avalon master does not support sink backpressure
 #master_write_from_file $claim_path mem_init/flash.bin $flash_imem_base
 
-# work around the issue by writing into small chunks so that FIFO does not fill up
+# work around lack of backpressure support by writing chunks of master FIFO size
 set chunks [llength [glob mem_init/chunks/*]]
 puts "Programming $chunks chunks"
 set addr $flash_imem_base
 for {set i 0} {$i<$chunks} {incr i} {
     set file [format "flash.%04d" $i]
     master_write_from_file $claim_path mem_init/chunks/$file $addr
-    set addr [expr $addr + 64]
+    set addr [expr $addr + 1024]
 }
 #master_read_to_file $claim_path mem_init/flash_readback.bin $flash_imem_base $bin_size
 #master_read_to_file $claim_path mem_init/ram_readback.bin 0x010000 65536
 
+# flush flashctrl cmd fifo to ensure writes have finished
+master_read_32 $claim_path $flash_base 1
+
 puts "Resetting system"
 master_write_32 $claim_path 0x40 0x00000003
 after 1
@@ -86,4 +89,4 @@ master_write_32 $claim_path 0x40 0x00000001
 master_write_32 $claim_path 0x40 0x00000000
 
 close_service master $claim_path
-puts "Done"
+puts "Done"