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Subject: Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag
 for struct serial_rs485
To: Andy Shevchenko <andy.shevchenko@gmail.com>
References: <1447338836-8785-1-git-send-email-matwey@sai.msu.ru>
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 <CAHp75Vdv-ycJfgA2xkjS2SrvL8N2vvrBMS-2d4ibBg-yvZying@mail.gmail.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        "Matwey V. Kornilov" <matwey@sai.msu.ru>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>, jslaby@suse.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>
From: Peter Hurley <peter@hurleysoftware.com>
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Date: Thu, 12 Nov 2015 20:11:16 -0500
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On 11/12/2015 07:41 PM, Andy Shevchenko wrote:
> On Thu, Nov 12, 2015 at 10:22 PM, Peter Hurley <peter@hurleysoftware.com> wrote:
>> On 11/12/2015 02:57 PM, One Thousand Gnomes wrote:
> 
>> An illustrative (kernel-space) example is the mess that is dmaengine_pause().
>> Some DMA implementations provide the means to stop and restart DMA without
>> losing data and some DMA implementations do not. Unfortunately, some
>> advertise they support dmaengine_pause() but only for lossy uses like audio.
>> Because the api hides this, the query interface for pause support is
>> useless.
> 
> The DMA pause() call means only pause with possibility to resume.
> There is a resume() call as well. Any driver which treats pause() as a
> complete stop is buggy driver and should be fixed.

How about pause _without_ the possibility to resume?

https://groups.google.com/d/msg/linux.kernel/Abe0hfGcgsw/H0se55wC558J