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Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag for struct serial_rs485

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On Fri, Nov 13, 2015 at 3:11 AM, Peter Hurley <peter@hurleysoftware.com> wrote:
> 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

Briefly what I got from the thread that Russel shows similar view on
the API, so that's why he was objecting to add pause/resume calls for
a specific hardware.

-- 
With Best Regards,
Andy Shevchenko
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[PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag for struct serial_rs485 "Matwey V. Kornilov" <matwey@sai.msu.ru> - 2015-11-12 15:40 +0100
  Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 Peter Hurley <peter@hurleysoftware.com> - 2015-11-12 21:30 +0100
    Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 Andy Shevchenko <andy.shevchenko@gmail.com> - 2015-11-13 01:50 +0100
      Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 Peter Hurley <peter@hurleysoftware.com> - 2015-11-13 02:20 +0100
        Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 Andy Shevchenko <andy.shevchenko@gmail.com> - 2015-11-13 02:30 +0100
          Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 Peter Hurley <peter@hurleysoftware.com> - 2015-11-13 03:00 +0100
    Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2015-11-14 16:30 +0100
  Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2015-11-12 21:50 +0100
    Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag  for struct serial_rs485 "Matwey V. Kornilov" <matwey@sai.msu.ru> - 2015-11-13 21:10 +0100

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