Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Received-SPF: pass (mxf98a: connection is authenticated)
Subject: Re: [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands
To:     Willy Tarreau <w@1wt.eu>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
References: <9ec3c54c-f8fe-22d7-783e-8cf9862405bb@robertabel.eu>
 <20180225235432.31209-1-rabel@robertabel.eu>
 <20180225235432.31209-2-rabel@robertabel.eu>
 <20180225235432.31209-3-rabel@robertabel.eu>
 <20180225235432.31209-4-rabel@robertabel.eu>
 <CANiq72mu2NkDx4XqXzcO39N8AZg50h+BxrONJ3eCc7LjJ0rJKg@mail.gmail.com>
 <50a2fd51-8bdb-d2b7-c2b3-7df638fdedde@robertabel.eu>
 <20180227051905.GA26781@1wt.eu>
From:   Robert Abel <rabel@robertabel.eu>
Message-ID: <911beeb5-529f-09bb-0e5a-c5b626adba60@robertabel.eu>
Date:   Wed, 28 Feb 2018 00:29:38 +0100
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <20180227051905.GA26781@1wt.eu>
Content-Type: text/plain; charset=utf-8
Content-Language: de-DE
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Willy,

On 27 Feb 2018 06:19, Willy Tarreau wrote:
> Well actually I don't see a problem there at all. The principle is simply
> to accept any sequence assigning x or y or both. If you write x4y2x6, it
> simply means that you changed your mind regarding x and that the last
> value (6) is the one you want. Just as if you wrote "^[[Lx4;^[[y2;^[[x6;".
> The while loop doesn't even try to do anything clever, it simply parses
> everything matching x and y followed by digits. I think the only reason
> for having both x and y processed in the same loop was to call
> charlcd_gotoxy() only once for both axes.

I didn't say it is a problem. It is however an edge case that incurs a
lot of code for little to no functionality.
I'd much prefer if we broke backwards compatibility here and actually
only parse the format that is indicated in the comment:

>         case 'x':       /* gotoxy : LxXXX[yYYY]; */
>         case 'y':       /* gotoxy : LyYYY[xXXX]; */
>  

Exactly one x command followed exactly by zero or one y command or
vice-versa.

If somebody changes their mind during the escape sequence, they can just
issue a new one instead of appending to the current one.

I'll post an example patch.

Regards,

Robert