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SubjectRE: [PATCH v9 15/18] input: cyapa: add gen3 trackpad device read firmware image function support
Date


> -----Original Message-----
> From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
> Sent: 2014年12月5日 1:47
> To: Dudley Du
> Cc: Dudley Du; rydberg@euromail.se; bleung@google.com;
> linux-input@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v9 15/18] input: cyapa: add gen3 trackpad device read
> firmware image function support
>
> On Mon, Nov 10, 2014 at 11:05:39AM +0000, Dudley Du wrote:
> > Thanks, Dmitry
> >
> > > -----Original Message-----
> > > From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
> > > Sent: 2014?11?10? 16:40
> > > To: Dudley Du
> > > Cc: rydberg@euromail.se; Dudley Du; bleung@google.com;
> > > linux-input@vger.kernel.org; linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v9 15/18] input: cyapa: add gen3 trackpad device read
> > > firmware image function support
> > >
> > > On Mon, Nov 03, 2014 at 04:33:07PM +0800, Dudley Du wrote:
> > > > Add read firmware image function supported for gen3 trackpad device,
> > > > it can be used through debugfs read_fw interface.
> > >
> > > Why do we need this? Can we do the same via usespace program accessing
> > > the i2c device through /dev/i2c-N?
> >
> > This interface is used to test and debug only. It's defined and required by the
> chromium projects.
> >
> > And in the driver side, becase the firmware image read process is done based on
> interrupt signal,
> > if do this in userspace through /dev/i2c-N, there will be two issues:
> > 1) for gen5, after each command, an interrupt will be asserted, so if throug
> /dev/i2c-N,
> > userspace program cannot get the interrupt signal.
> > 2) and when the interrupt signal assert, driver won't know it’s a command signal
> for image read,
> > so it will try to process it as data report.
> > To avoid this, additional interface must be added to mark the image read status
> and
> > block interrupt signal to be process as data report.
>
> I believe that while userspace acc4esses the device through /dev/i2c-N
> you should unbind the cyapa driver from the device (via sysfs driver
> core bind/unbind attribute) so that it doe snot get in the way. Once
> diagnostics is done you can bind the driver back to device, restoring
> normal operation.
>
> That is how we are planning to handle other devices at factory as
> well.

Thanks, I will remove the debugfs interfaces from the patach series.

>
> Thanks.
>
> --
> Dmitry

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