[U-Boot] [PATCH v7 15/16] lcd: Add CONFIG_CONSOLE_SCROLL_LINES option to speed console

[Simon Glass]

When the cursor position gets to the end of the LCD console we normally
scroll by one line. This adds an option to increase that value.

Console scrolling is often slow, and if a large amount of output is
being sent, increasing this option to 10 or so will speed things up
considerably.

Signed-off-by: Simon Glass <sjg at chromium.org>
---
Changes in v5:
- Fix CONFIG_CONSOLE_SCROLL_LINES commit title
- Fix misleading comments in common/lcd.c

Changes in v4:
- Use CONFIG_CONSOLE_SCROLL_LINES instead of CONSOLE_SCROLL_LINES
- Put default CONFIG_CONSOLE_SCROLL_LINES at top of file

Changes in v3:
- Fix tiny bug in mult-line lcd scrolling

 README       |    6 ++++++
 common/lcd.c |   22 +++++++++++++++++-----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/README b/README
index 0ffe7b8..78fc1a2 100644
--- a/README
+++ b/README
@@ -1456,6 +1456,12 @@ The following options need to be configured:
 		here, since it is cheaper to change data cache settings on
 		a per-section basis.
 
+		CONFIG_CONSOLE_SCROLL_LINES
+
+		When the console need to be scrolled, this is the number of
+		lines to scroll by. It defaults to 1. Increasing this makes
+		the console jump but can help speed up operation when scrolling
+		is slow.
 
 - Splash Screen Support: CONFIG_SPLASH_SCREEN
 
diff --git a/common/lcd.c b/common/lcd.c
index 74fa3f9..3d53651 100644
--- a/common/lcd.c
+++ b/common/lcd.c
@@ -76,6 +76,11 @@
 #define CONFIG_LCD_ALIGNMENT PAGE_SIZE
 #endif
 
+/* By default we scroll by a single line */
+#ifndef CONFIG_CONSOLE_SCROLL_LINES
+#define CONFIG_CONSOLE_SCROLL_LINES 1
+#endif
+
 DECLARE_GLOBAL_DATA_PTR;
 
 ulong lcd_setmem (ulong addr);
@@ -131,12 +136,20 @@ void lcd_set_flush_dcache(int flush)
 
 static void console_scrollup(void)
 {
-	/* Copy up rows ignoring the first one */
-	memcpy(CONSOLE_ROW_FIRST, CONSOLE_ROW_SECOND, CONSOLE_SCROLL_SIZE);
+	const int rows = CONFIG_CONSOLE_SCROLL_LINES;
+
+	/* Copy up rows ignoring those that will be overwritten */
+	memcpy(CONSOLE_ROW_FIRST,
+	       lcd_console_address + CONSOLE_ROW_SIZE * rows,
+	       CONSOLE_SIZE - CONSOLE_ROW_SIZE * rows);
+
+	/* Clear the last rows */
+	memset(lcd_console_address + CONSOLE_SIZE - CONSOLE_ROW_SIZE * rows,
+		COLOR_MASK(lcd_color_bg),
+	       CONSOLE_ROW_SIZE * rows);
 
-	/* Clear the last one */
-	memset(CONSOLE_ROW_LAST, COLOR_MASK(lcd_color_bg), CONSOLE_ROW_SIZE);
 	lcd_sync();
+	console_row -= rows;
 }
 
 /*----------------------------------------------------------------------*/
@@ -165,7 +178,6 @@ static inline void console_newline(void)
 	if (console_row >= CONSOLE_ROWS) {
 		/* Scroll everything up */
 		console_scrollup();
-		--console_row;
 	} else {
 		lcd_sync();
 	}
-- 
1.7.7.3