2020-11-03 10:01:44

by Lars Poeschel

[permalink] [raw]
Subject: [PATCH v6 19/25] auxdisplay: hd44780_common: Reduce clear_display timeout

From: Lars Poeschel <[email protected]>

Digging in the hd44780 datasheet revealed that the timeout needed after
clearing the whole display is only 1,64ms not 15ms. So we can reduce
that timeout.

Link: https://lore.kernel.org/lkml/[email protected]/
Link: https://www.crystalfontz.com/controllers/Hitachi/HD44780/433/

Signed-off-by: Lars Poeschel <[email protected]>
---
Changes in v3:
- This patch is new in v3
---
drivers/auxdisplay/hd44780_common.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/auxdisplay/hd44780_common.c b/drivers/auxdisplay/hd44780_common.c
index c528fb8e8808..bd93a4d3367e 100644
--- a/drivers/auxdisplay/hd44780_common.c
+++ b/drivers/auxdisplay/hd44780_common.c
@@ -83,8 +83,8 @@ int hd44780_common_clear_display(struct charlcd *lcd)
struct hd44780_common *hdc = lcd->drvdata;

hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CLEAR);
- /* we must wait a few milliseconds (15) */
- long_sleep(15);
+ /* datasheet says to wait 1,64 milliseconds */
+ long_sleep(2);
return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_clear_display);
--
2.28.0