Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 25 Feb 2022 08:42:56 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Sergey Senozhatsky <senozhatsky@chromium.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Petr Mladek <pmladek@suse.com>,
        John Ogness <john.ogness@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Wander Lairson Costa <wander@redhat.com>,
        Willy Tarreau <w@1wt.eu>,
        David Laight <David.Laight@aculab.com>
Subject: Re: Strange output on the console
Message-ID: <20220225084256.071dcf82@gandalf.local.home>
In-Reply-To: <20220225083209.24bafe2c@gandalf.local.home>
References: <20220224230035.36547137@gandalf.local.home>
        <Yhhh730RX1HpdXp2@google.com>
        <Yhhj9MLZTrhjSWUE@google.com>
        <20220225083209.24bafe2c@gandalf.local.home>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Fri, 25 Feb 2022 08:32:09 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Fri, 25 Feb 2022 14:07:00 +0900
> Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
> 
> > > Steven, did you notice this recently?
> > > May I perhaps suggest git bisect? (sorry)    
> > 
> > On the off chance - do you have this revert in your kernel?
> > 
> > commit 6a7b9f002eca6788d346c16a6ff0c218b41f8d1d
> > Author: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Date:   Wed Jan 26 14:33:58 2022 +0100
> > 
> >     Revert "tty: serial: Use fifo in 8250 console driver"
> > 
> >     This reverts commit 5021d709b31b8a14317998a33cbc78be0de9ab30.
> > 
> >     The patch is still a bit buggy, and this breaks some other hardware
> >     types.  It needs to be resubmitted in a non-buggy way, and make sure the
> >     other hardware types also continue to work properly.  
> 
> My tree does not have this.
> 
> I just applied it and I'm building now. I'll let you know if this fixes the
> issue or not.

Mystery solved. Thanks Sergey!

After applying the above revert patch the funky characters go away.
Removing the revert (putting back the problem commit) the problem reappears.

Greg,

I have the hardware that the code breaks. I will be willing to test the new
changes to make sure it's done in a "non-buggy" way. At least for my
hardware (two boxes that had the issue, but slightly different).


-- Steve