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Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error

From Oliver Neukum <oneukum@suse.com>
Newsgroups linux.kernel
Subject Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error
Date 2016-08-02 16:10 +0200
Message-ID <s1Iyn-5ut-79@gated-at.bofh.it> (permalink)
References <rZYed-1tJ-15@gated-at.bofh.it> <s1Iym-5ut-47@gated-at.bofh.it> <s1Iym-5ut-45@gated-at.bofh.it>
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On Tue, 2016-08-02 at 09:54 -0400, Robert Foss wrote:
> 
> On 2016-08-02 08:23 AM, Oliver Neukum wrote:
> > On Thu, 2016-07-28 at 14:19 -0400, robert.foss@collabora.com wrote:
> >> From: Prathmesh Prabhu <pprabhu@chromium.org>
> >>
> >> Implemented queued response handling. This queue is processed every
> >> time the
> >> WDM_READ flag is cleared.
> >>
> >> In case of a read error, userspace may not actually read the data,
> >> since the
> >> driver returns an error through wdm_poll. After this, the underlying
> >> device may
> >> attempt to send us more data, but the queue is not processed. While
> >> userspace is
> >> also blocked, because the read error is never cleared.
> >
> > Could you explain why user space cannot just read more data?
> > That will clear the error.
> 
> Userspace certainly could read more data, but for the case when 
> userspace doesn't read and clear a potential an error, we still would 
> like to not be stuck if the device sends more data.
> 
> I hope that answers your question, if not I'll try to be more elaborate.

Clear, but why does that require the suppression of an error condition?
errors should always be delivered.

	Regards
		Oliver

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Thread

[PACTH v1] cdc-wdm: Clear read pipeline in case of error robert.foss@collabora.com - 2016-07-28 20:30 +0200
  Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Robert Foss <robert.foss@collabora.com> - 2016-08-02 16:10 +0200
    Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Oliver Neukum <oneukum@suse.com> - 2016-08-02 16:10 +0200
      Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Robert Foss <robert.foss@collabora.com> - 2016-08-02 16:40 +0200
        Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Oliver Neukum <oneukum@suse.com> - 2016-08-03 12:50 +0200
          Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Robert Foss <robert.foss@collabora.com> - 2016-08-04 19:50 +0200
            Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Oliver Neukum <oneukum@suse.com> - 2016-08-07 11:10 +0200
              Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Robert Foss <robert.foss@collabora.com> - 2016-08-08 16:40 +0200
  Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error Oliver Neukum <oneukum@suse.com> - 2016-08-02 16:50 +0200

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