From: Lars Poeschel <poeschel@lemonage.de>
To: Willy Tarreau <w@1wt.eu>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 31/32] auxdisplay: charlcd: Do not print chars at end of line
Date: Tue, 22 Sep 2020 11:44:22 +0200 [thread overview]
Message-ID: <20200922094422.ucj24ohtervhcetv@lem-wkst-02.lemonage> (raw)
In-Reply-To: <20200922052701.GB16386@1wt.eu>
On Tue, Sep 22, 2020 at 07:27:01AM +0200, Willy Tarreau wrote:
> On Mon, Sep 21, 2020 at 04:46:43PM +0200, poeschel@lemonage.de wrote:
> > From: Lars Poeschel <poeschel@lemonage.de>
> >
> > Skip printing characters at the end of a display line. This fits to the
> > behaviour we already had, that the cursor is nailed to last position of
> > a line.
>
> Just very old memories, but wasn't this used with the ability to shift
> the display ? IIRC the HD44780 has a 2x64 chars buffer and you can make
> the buffered characters appear when you shift the display. That's akin
> to seeing the display as an adjustable window over the buffer. I don't
> remember having used that feature, so if it didn't previously work, please
> disregard my comment, I just want to be sure we don't break a feature
> others might be relying on.
Yes, indeed. But this is a point, where this was inconsistent. The
feature you described worked only for displays with 2 lines or less. On
displays with 4 lines there simply is no buffer that is not visible and
in this case it sticks to the end of the line already.
To make this work for all displays this would require a whole lot of
work. We would need a fallback implementation that emulates this in
software and then redraws the whole display from that software
(linux-side) buffer when shifting.
Currently my patchset cuts this feature for displays with one or two
lines. I don't see clean an easy way to leave that in. Any ideas ?
Regards,
Lars
next prev parent reply other threads:[~2020-09-22 9:44 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 8:24 [PATCH 1/3] auxdisplay: Make charlcd.[ch] more general Lars Poeschel
2019-10-16 8:26 ` [PATCH 2/3] auxdisplay: lcd2s DT binding doc Lars Poeschel
2019-10-29 1:24 ` Rob Herring
2019-10-16 8:27 ` [PATCH 3/3] auxdisplay: add a driver for lcd2s character display Lars Poeschel
2019-10-16 16:53 ` [PATCH 1/3] auxdisplay: Make charlcd.[ch] more general Miguel Ojeda
2019-10-17 8:07 ` Lars Poeschel
2019-10-17 11:26 ` Andy Shevchenko
2019-10-18 15:08 ` Miguel Ojeda
2019-10-18 15:33 ` Joe Perches
2019-10-18 21:55 ` Andi Kleen
2020-09-21 14:46 ` [PATCH v2 00/33] Make charlcd device independent poeschel
2020-09-21 14:46 ` [PATCH v2 01/32] auxdisplay: Use an enum for charlcd backlight on/off ops poeschel
2020-09-21 14:46 ` [PATCH v2 02/32] auxdisplay: Introduce hd44780_common.[ch] poeschel
2020-09-21 15:30 ` Randy Dunlap
2020-09-21 14:46 ` [PATCH v2 03/32] auxdisplay: Move hwidth and bwidth to struct hd44780_common poeschel
2020-09-21 14:46 ` [PATCH v2 04/32] auxdisplay: Move ifwidth " poeschel
2020-09-21 14:46 ` [PATCH v2 05/32] auxdisplay: Move write_data pointer to hd44780_common poeschel
2020-09-21 14:46 ` [PATCH v2 06/32] auxdisplay: Move write_cmd pointers to hd44780 drivers poeschel
2020-09-21 14:46 ` [PATCH v2 07/32] auxdisplay: Move addr out of charlcd_priv poeschel
2020-09-21 14:46 ` [PATCH v2 08/32] auxdisplay: hd44780_common_print poeschel
2020-09-21 14:46 ` [PATCH v2 09/32] auxdisplay: provide hd44780_common_gotoxy poeschel
2020-09-21 14:46 ` [PATCH v2 10/32] auxdisplay: add home to charlcd_ops poeschel
2020-09-21 14:46 ` [PATCH v2 11/32] auxdisplay: Move clear_display to hd44780_common poeschel
2020-09-21 14:46 ` [PATCH v2 12/32] auxdisplay: make charlcd_backlight visible " poeschel
2020-09-21 14:46 ` [PATCH v2 13/32] auxdisplay: Make use of enum for backlight on / off poeschel
2020-09-21 14:46 ` [PATCH v2 14/32] auxdisplay: Move init_display to hd44780_common poeschel
2020-09-21 14:46 ` [PATCH v2 15/32] auxdisplay: implement hd44780_common_shift_cursor poeschel
2020-09-21 14:46 ` [PATCH v2 16/32] auxdisplay: Implement hd44780_common_display_shift poeschel
2020-09-21 14:46 ` [PATCH v2 17/32] auxdisplay: Implement a hd44780_common_display poeschel
2020-09-21 14:46 ` [PATCH v2 18/32] auxdisplay: Implement hd44780_common_cursor poeschel
2020-09-21 14:46 ` [PATCH v2 19/32] auxdisplay: Implement hd44780_common_blink poeschel
2020-09-21 14:46 ` [PATCH v2 20/32] auxdisplay: cleanup unnecessary hd44780 code in charlcd poeschel
2020-09-21 14:46 ` [PATCH v2 21/32] auxdisplay: Implement hd44780_common_fontsize poeschel
2020-09-21 14:46 ` [PATCH v2 22/32] auxdisplay: Implement hd44780_common_lines poeschel
2020-09-21 14:46 ` [PATCH v2 23/32] auxdisplay: Remove unnecessary hd44780 from charlcd poeschel
2020-09-21 14:46 ` [PATCH v2 24/32] auxdisplay: Move char redefine code to hd44780_common poeschel
2020-09-21 14:46 ` [PATCH v2 25/32] auxdisplay: Call charlcd_backlight in place poeschel
2020-09-21 14:46 ` [PATCH v2 26/32] auxdisplay: Move clear_fast to hd44780 poeschel
2020-09-21 14:46 ` [PATCH v2 27/32] auxdisplay: remove naive display clear impl poeschel
2020-09-21 14:46 ` [PATCH v2 28/32] auxdisplay: hd44780: Remove clear_fast poeschel
2020-09-22 5:22 ` Willy Tarreau
2020-09-22 8:49 ` Lars Poeschel
2020-09-22 9:21 ` Willy Tarreau
2020-09-22 11:51 ` Lars Poeschel
2020-09-21 14:46 ` [PATCH v2 29/32] auxdisplay: charlcd: replace last device specific stuff poeschel
2020-09-21 14:46 ` [PATCH v2 30/32] auxdisplay: Change gotoxy calling interface poeschel
2020-09-21 14:46 ` [PATCH v2 31/32] auxdisplay: charlcd: Do not print chars at end of line poeschel
2020-09-22 5:27 ` Willy Tarreau
2020-09-22 9:44 ` Lars Poeschel [this message]
2020-09-22 10:04 ` Willy Tarreau
2020-09-22 10:20 ` Miguel Ojeda
2020-09-22 11:51 ` Lars Poeschel
2020-09-21 14:46 ` [PATCH v2 32/32] auxdisplay: lcd2s DT binding doc poeschel
2020-09-22 15:58 ` Rob Herring
2020-10-02 13:45 ` Lars Poeschel
2020-09-21 14:46 ` [PATCH v2 33/33] auxdisplay: add a driver for lcd2s character display poeschel
2020-09-21 15:33 ` Randy Dunlap
2020-10-02 12:42 ` Pavel Machek
2020-10-02 13:15 ` Lars Poeschel
2020-09-22 5:31 ` [PATCH v2 00/33] Make charlcd device independent Willy Tarreau
2020-09-22 10:23 ` Miguel Ojeda
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