auxdisplay: hd44780: move cursor home after clear display command
authorHugo Villeneuve <hvilleneuve@dimonoff.com>
Sat, 22 Jul 2023 18:09:25 +0000 (14:09 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 8 Dec 2023 07:51:16 +0000 (08:51 +0100)
commita491c7be35ed8345270cb80c4a0ff154559bd79e
treeb50e760bcad16a3d352e180e16c3668221811c23
parent7f2116777541bd116c55188a8ce5729dd2a52444
auxdisplay: hd44780: move cursor home after clear display command

commit 35b464e32c8bccef435e415db955787ead4ab44c upstream.

The DISPLAY_CLEAR command on the NewHaven NHD-0220DZW-AG5 display
does NOT change the DDRAM address to 00h (home position) like the
standard Hitachi HD44780 controller. As a consequence, the starting
position of the initial string LCD_INIT_TEXT is not guaranteed to be
at 0,0 depending on where the cursor was before the DISPLAY_CLEAR
command.

Extract of DISPLAY_CLEAR command from datasheets of:

    Hitachi HD44780:
        ... It then sets DDRAM address 0 into the address counter...

    NewHaven NHD-0220DZW-AG5 datasheet:
... This instruction does not change the DDRAM Address

Move the cursor home after sending DISPLAY_CLEAR command to support
non-standard LCDs.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: David Reaver <me@davidreaver.com>
Link: https://lore.kernel.org/r/20230722180925.1408885-1-hugo@hugovil.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/auxdisplay/hd44780_common.c