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Date:   Thu, 19 Jul 2018 12:07:05 +0100
From:   Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To:     Ludovic Desroches <ludovic.desroches@microchip.com>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        <linux-serial@vger.kernel.org>, <linux-arch@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <jslaby@suse.com>,
        <arnd@arndb.de>, <richard.genoud@gmail.com>,
        <nicolas.ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] tty/serial_core: add ISO7816 infrastructure
Message-ID: <20180719120705.4a2fde04@alans-desktop>
In-Reply-To: <20180713080129.2ifw7crjksvaxxpq@M43218.corp.atmel.com>
References: <20180711131638.12622-1-ludovic.desroches@microchip.com>
        <20180711131638.12622-2-ludovic.desroches@microchip.com>
        <20180712145808.GA22502@kroah.com>
        <20180713080129.2ifw7crjksvaxxpq@M43218.corp.atmel.com>
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> >   
> > > +	if (!port->iso7816_config)
> > > +		return -ENOIOCTLCMD;  
> > 
> > Why this error value?
> >   
> 
> It was a mimic of RS485.

Which is what you want - it means the upper tty layer knows to offer the
ioctl to other places and then return appropriately.

Alan