linux-kernel - Re: [PATCH v2] auxdisplay: hd44780: move cursor home after clear display command

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Message-ID: <CANiq72=MsytTivumoe-F7sr_00om8tjvV_54mEXQf52YCiM5wQ@mail.gmail.com>
Date:   Sat, 19 Aug 2023 21:58:19 +0200
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Hugo Villeneuve <hugo@...ovil.com>
Cc:     Miguel Ojeda <ojeda@...nel.org>,
        Hugo Villeneuve <hvilleneuve@...onoff.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] auxdisplay: hd44780: move cursor home after clear
 display command

On Sat, Jul 22, 2023 at 8:09 PM Hugo Villeneuve <hugo@...ovil.com> wrote:
>
> From: Hugo Villeneuve <hvilleneuve@...onoff.com>
>
> 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@...onoff.com>

Applied to `auxdisplay` -- thanks everyone!

Cheers,
Miguel