Optimize lcd-ssd1303 driver (clip series)

Saves 100+ bytes (50 of it in iram), saves a bit of power

Internal LCD clock decreased but with added efficiency of drawing routines
loses only around 2 Hz on the scanrate (~75Hz) while fps is slightly increased

Column offsets are now calculated outside the loops saving a few instructions

Passing a LCD_NOP command after lcd_update turns off Data/Cmd# gpio
saving a bit more power

Added a function lcd_write_cmd_triple() that allows 3 commands to be sent at once
when enabled with LCD_USE_FIFO_FOR_COMMANDS it sends them back to back without
checking FIFO status in between or sending to thhe D/C# Gpio.
Makes an assumption about the FIFO being large enough to
accept 3 commands after being emptied which should be the case on the
clipv1, clipv2, clipplus. I have only enabled it for the clip plus
as thats the only device I have to test it on.

On clip+ the SSP clock is now turned off when screen is off

Change-Id: Ib5fd24697bfe4ac8b8ee017361e789e4a7910d21

1 files changed, 10 insertions, 0 deletions

diff --git a/firmware/target/arm/as3525/lcd-clip.h b/firmware/target/arm/as3525/lcd-clip.h
index eb76401bc0..3bde92430c 100644
--- a/firmware/target/arm/as3525/lcd-clip.h
+++ b/firmware/target/arm/as3525/lcd-clip.h
@@ -18,12 +18,22 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
+#ifndef __LCDCLIP_H__
+#define __LCDCLIP_H__
 
 #include "config.h"
 
+#if !defined(BOOTLOADER) && defined(SANSA_CLIPPLUS) /* only tested for clipplus */
+/* Ensure empty FIFO for lcd commands is at least 3 deep */
+#define LCD_USE_FIFO_FOR_COMMANDS
+#endif
+
+void lcd_write_cmd_triplet(int cmd1, int cmd2, int cmd3);
+
 /* return variant number: 0 = clipv1, clipv2, old clip+, 1 = newer clip+ */
 int lcd_hw_init(void) INIT_ATTR;
 
 /* target-specific power enable */
 void lcd_enable_power(bool onoff);
 
+#endif /*__LCDCLIP_H__*/