From: Johan Hovold <johan@kernel.org>
To: Andreas Kemnade <andreas@kemnade.info>
Cc: Johan Hovold <johan@kernel.org>,
robh+dt@kernel.org, mark.rutland@arm.com,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Discussions about the Letux Kernel
<letux-kernel@openphoenux.org>
Subject: Re: [PATCH v2 2/5] gnss: sirf: power on logic for devices without wakeup signal
Date: Tue, 15 Jan 2019 10:08:25 +0100 [thread overview]
Message-ID: <20190115090825.GM3691@localhost> (raw)
In-Reply-To: <20190114225802.4dcd8cd2@aktux>
On Mon, Jan 14, 2019 at 10:58:02PM +0100, Andreas Kemnade wrote:
> On Mon, 14 Jan 2019 11:51:29 +0100
> Johan Hovold <johan@kernel.org> wrote:
>
> here is a second part of a reply.
I'm not sure I received the first part if you're saying you replied to
my mail in two parts?
> [...]
> > > > In pseudo code we have:
> > > >
> > > > activate:
> > > > - toggle on-off
> > > > - wait(data-received, ACTIVATE_TIMEOUT + REPORT_CYCLE)
> > > > - reception: success
> > >
> > > Note: we can also get the goodbye/shutdown message from the chip here
> > > so there are chances of a false success, but since we initially power down,
> > > we will rule out wrong state here.
> >
> > Good point. Unless we know the current state, we'd need to sleep for
> > HIBERNATE_TIMEOUT before waiting for data reception.
>
> And probably this also magically (together with my
> runtime_get/put()-pair) in _probe()) worked around the
> problems fixed by the.
> gnss: sirf: fix activation retry handling
The retry-handling fix would only avoid a successful last retry attempt
incorrectly being reported as a failure, so I don't think that would
change much here.
> Well, with the last patchset and short report cycle we can detect state
> changes to off state reliably but state changes to on state
> only unreliably (which was, as said, not the intention). If the GPS chip
> behaves well enough, we will not see trouble.
>
> Now with long report cycles: Off state detection will always return
> success. On state detection (in its current wonky form) will see the
> state change messages and will also always return success. If initial
> state is correct, this works at least in a wonky way.
>
> I do not like these wonky things too much. So I would rather see
> well-defined behavior with well-known limitations.
>
> State change failures are probably not only a theoretical thing,
> so it is a good idea to track that.
Good, sounds like we're on the same page then.
Thanks,
Johan
next prev parent reply other threads:[~2019-01-15 9:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-09 19:51 [PATCH v2 0/5] gnss: sirf: add support for w2sg0004 + lna Andreas Kemnade
2018-12-09 19:51 ` [PATCH v2 1/5] gnss: sirf: write data to gnss only when the gnss device is open Andreas Kemnade
2019-01-10 12:02 ` Johan Hovold
2019-01-13 20:50 ` Andreas Kemnade
2019-01-14 12:00 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 2/5] gnss: sirf: power on logic for devices without wakeup signal Andreas Kemnade
2019-01-10 12:10 ` Johan Hovold
2019-01-10 22:02 ` Andreas Kemnade
2019-01-14 10:51 ` Johan Hovold
2019-01-14 12:13 ` Andreas Kemnade
2019-01-22 8:38 ` Johan Hovold
2019-01-14 21:58 ` Andreas Kemnade
2019-01-15 9:08 ` Johan Hovold [this message]
2018-12-09 19:51 ` [PATCH v2 3/5] dt-bindings: gnss: add w2sg0004 compatible string Andreas Kemnade
2019-01-10 12:12 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 4/5] gnss: sirf: add a separate supply for a lna Andreas Kemnade
2018-12-10 7:42 ` [Letux-kernel] " H. Nikolaus Schaller
2019-01-10 12:25 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 5/5] dt-bindings: gnss: add lna-supply property Andreas Kemnade
2019-01-10 12:27 ` Johan Hovold
2019-01-10 17:07 ` Andreas Kemnade
2019-01-14 9:15 ` Johan Hovold
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