From: Anton Vorontsov <avorontsov@mvista•com>
To: Tabi Timur-B04825 <B04825@freescale•com>
Cc: "a.zummo@towertech•it" <a.zummo@towertech•it>,
"rtc-linux@googlegroups•com" <rtc-linux@googlegroups•com>,
"p_gortmaker@yahoo•com" <p_gortmaker@yahoo•com>,
Jain Priyanka-B32167 <B32167@freescale•com>,
"akpm@linux-foundation•org" <akpm@linux-foundation•org>,
"linuxppc-dev@lists•ozlabs.org" <linuxppc-dev@lists•ozlabs.org>
Subject: Re: [rtc-linux] Re: [PATCH] Add support for pt7c4338 (rtc device) in rtc-ds1307 driver
Date: Mon, 30 May 2011 20:57:45 +0400 [thread overview]
Message-ID: <20110530165745.GA2758@oksana.dev.rtsoft.ru> (raw)
In-Reply-To: <BANLkTi=H2rHSjTvRK5+SPhW26qCNUBMxbA@mail.gmail.com>
On Mon, May 30, 2011 at 02:29:58PM +0000, Tabi Timur-B04825 wrote:
> On Mon, May 30, 2011 at 3:24 AM, Wolfram Sang <w.sang@pengutronix•de> wrote:
>
> > The first place where this should be mentioned is the datasheet of the
> > pt-chip, so you might ask the producer to add this information (don't
> > expect much to happen, though).
>
> It's true that the data sheet does not mention that it's identical to
> the DS1307, but that's still no excuse for not noticing it and writing
> a whole driver for it. :-(
>
> > IIRC I asked you explicitly for the differences between the chips. If
> > there are none, you can use the driver directly, right? :)
>
> Yes. The device tree node for the PT7C4338 device should just say
>
> /* The board has a PT7C4338, which is compatible with the DS1307 */
> compatible = "dallas,ds1307";
While it seems to be 100% compatible, there could be chip-specific
bugs or some interesting features that are hidden behind "reserved"
bits and registers.
So I think device tree should not lie about the chip model. Doing
'compatible = "pericom,pt7c4338", "dallas,ds1307"' is perfectly fine.
Note that today the several compatible entries approach gives you
almost nothing, as you will need to add pt7c4338 entry into the driver
anyway.
I tried to improve this, i.e. make linux do OF-matching on the most
generic compatible entry (the last one):
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg21196.html
It was received coldly though:
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg22041.html
http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg21273.html
--
Anton Vorontsov
Email: cbouatmailru@gmail•com
next prev parent reply other threads:[~2011-05-30 17:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-26 7:03 [PATCH] Add support for pt7c4338 (rtc device) in rtc-ds1307 driver Priyanka Jain
2011-05-26 9:10 ` Wolfram Sang
2011-05-30 4:47 ` Jain Priyanka-B32167
2011-05-30 8:24 ` Wolfram Sang
2011-05-30 14:29 ` [rtc-linux] " Tabi Timur-B04825
2011-05-30 14:50 ` Wolfram Sang
2011-05-30 16:57 ` Anton Vorontsov [this message]
2011-06-03 18:03 ` Grant Likely
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