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From: Aleksandar Markovic <aleksandar.m.mail@gmail.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Rajath Shashidhara <rajaths@cs.utexas.edu>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: Looking for issues/features for my first contribution
Date: Sat, 9 Nov 2019 22:08:36 +0100
Message-ID: <CAL1e-=jONDYiF+W6cEvrDFN_RkGSS3FVmaaj2-YE0RpO=GOb7w@mail.gmail.com> (raw)
In-Reply-To: <CAFEAcA-tNBNGE75+MZ3+r_9iLA-_3+meoseVxhgzJZ5PvDofuA@mail.gmail.com>

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On Saturday, November 9, 2019, Peter Maydell <peter.maydell@linaro.org>
wrote:

> On Fri, 8 Nov 2019 at 19:32, Aleksandar Markovic
> <aleksandar.m.mail@gmail.com> wrote:
> >
> > > [a] Is there any particular reason that you picked DS3231 ? Linux
> kernel
> > > has drivers for DS3232/34 only [1]. I did read the datasheets of both
> > > 3232 & 3231 and found that they are quite similar except for the 236
> > > bytes of SRAM support found only in 3232.
> > >
> >
> > Yes, DS3231 is a part of a board we want to support in future.
>
> We should probably prefer to go with a device that's a
> missing part of a board we already support -- generally
> the project prefers not to take device models that don't
> have a use, ie they go in with the board model rather
> than before. This also means we have some way of testing
> the code :-)
>
>
All agreed, Peter.

However, there is an additional interesting aspect here:

DS3231 is a fairly common module for RasPi. (and, is common for some other
systems with non-arm cpus too)

I hoped that setting up RasPi emulation with newly created RTC device would
be a peace of cake, but it might be that I was wrong. I see certain
inconsistency between our command line switches "-rtc" and "-watchdog".
Using "-watchdog", a watchdog timer model can be specified, but for "-rtc",
it looks, there is no such posibility.

Given modularity of RasPi, wouldn't it be nice for end users to be able to
specify an RTC via command line?

If usage of command line is ruled out, what would be an alternative way to
integrate particular RTC support in RasPi (for any QEMU-supported RTC, not
only (for now, just envisioned) DS3231)?

Sory if I missed something big here.

Yours,
Aleksandar



> thanks
> -- PMM
>

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<br><br>On Saturday, November 9, 2019, Peter Maydell &lt;<a href="mailto:peter.maydell@linaro.org">peter.maydell@linaro.org</a>&gt; wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Fri, 8 Nov 2019 at 19:32, Aleksandar Markovic<br>
&lt;<a href="mailto:aleksandar.m.mail@gmail.com">aleksandar.m.mail@gmail.com</a>&gt; wrote:<br>
&gt;<br>
&gt; &gt; [a] Is there any particular reason that you picked DS3231 ? Linux kernel<br>
&gt; &gt; has drivers for DS3232/34 only [1]. I did read the datasheets of both<br>
&gt; &gt; 3232 &amp; 3231 and found that they are quite similar except for the 236<br>
&gt; &gt; bytes of SRAM support found only in 3232.<br>
&gt; &gt;<br>
&gt;<br>
&gt; Yes, DS3231 is a part of a board we want to support in future.<br>
<br>
We should probably prefer to go with a device that&#39;s a<br>
missing part of a board we already support -- generally<br>
the project prefers not to take device models that don&#39;t<br>
have a use, ie they go in with the board model rather<br>
than before. This also means we have some way of testing<br>
the code :-)<br>
<br></blockquote><div><br></div><div>All agreed, Peter.</div><div><br></div><div>However, there is an additional interesting aspect here:</div><div><br></div><div>DS3231 is a fairly common module for RasPi. (and, is common for some other systems with non-arm cpus too)</div><div><br></div><div>I hoped that setting up RasPi emulation with newly created RTC device would be a peace of cake, but it might be that I was wrong. I see certain inconsistency between our command line switches &quot;-rtc&quot; and &quot;-watchdog&quot;. Using &quot;-watchdog&quot;, a watchdog timer model can be specified, but for &quot;-rtc&quot;, it looks, there is no such posibility.</div><div><br></div><div>Given modularity of RasPi, wouldn&#39;t it be nice for end users to be able to specify an RTC via command line?</div><div><br></div><div>If usage of command line is ruled out, what would be an alternative way to integrate particular RTC support in RasPi (for any QEMU-supported RTC, not only (for now, just envisioned) DS3231)?</div><div><br></div><div>Sory if I missed something big here.</div><div><br></div><div>Yours,</div><div>Aleksandar</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
thanks<br>
-- PMM<br>
</blockquote>

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 23:50 Rajath Shashidhara
2019-11-07 10:37 ` Aleksandar Markovic
2019-11-07 13:33   ` Aleksandar Markovic
2019-11-07 18:49     ` Rajath Shashidhara
2019-11-08  2:39     ` Rajath Shashidhara
2019-11-08  9:08       ` Alex Bennée
2019-11-08 13:05         ` Richard Henderson
2019-11-08 19:31       ` Aleksandar Markovic
2019-11-09 16:01         ` Peter Maydell
2019-11-09 21:08           ` Aleksandar Markovic [this message]
2019-11-10 14:33             ` Peter Maydell
2019-11-08 19:36       ` Aleksandar Markovic
2019-11-08 21:54         ` BALATON Zoltan
2019-11-09 19:46       ` Aleksandar Markovic
2019-11-09 21:33         ` Rajath Shashidhara
2019-11-09 23:55           ` Aleksandar Markovic
2019-11-07 11:18 ` Alex Bennée
2019-11-07 13:54 ` Stefan Hajnoczi
2019-11-07 18:51   ` Rajath Shashidhara

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