RE: [rtc-linux] [PATCH] RTC driver(Linux) for PT7C4338 chip.

Hi Andrew Morton,

I have added the support for pt7c4338 in Dallas driver rtc-ds1307.c as sugg=
ested by Wolfram Sang
And send the patch "Add support for pt7c4338 (rtc device) in rtc-ds1307 dri=
ver" for the same which will supersede the previous patch.

Please let me know if anything else is required.

Thanks
Priyanka

-----Original Message-----
From: Andrew Morton [mailto:akpm@linux-foundation.org]
Sent: Thursday, May 26, 2011 5:26 AM
To: Jain Priyanka-B32167
Cc: Wolfram Sang; rtc-linux@googlegroups.com; linuxppc-
dev@lists.ozlabs.org; a.zummo@towertech.it; p_gortmaker@yahoo.com
Subject: Re: [rtc-linux] [PATCH] RTC driver(Linux) for PT7C4338 chip.
=20
On Thu, 10 Mar 2011 11:06:27 +0000
Jain Priyanka-B32167 [off-list ref] wrote:
=20

quoted

Hi Wolfram,

quoted

-----Original Message-----
From: Wolfram Sang [mailto:w.sang@pengutronix.de]
Sent: Thursday, March 10, 2011 2:24 PM
To: Jain Priyanka-B32167
Cc: rtc-linux@googlegroups.com; linuxppc-dev@lists.ozlabs.org;
a.zummo@towertech.it; p_gortmaker@yahoo.com;
akpm@linux-foundation.org
Subject: Re: [rtc-linux] [PATCH] RTC driver(Linux) for PT7C4338 chip.

Hi Priyanka,

quoted

Though register-set looks identical but features were different.

Can you tell what exactly is different?

I will check both the devices data sheets again in detail and will get

back on this.

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And also manufacturer is different.

That does not matter. If you look at ds_type, there are already
different manufacturers. They will be correctly distinguished by
i2c_device_id. The name of the driver itself is, well, just a name.

quoted

But still it might be possible that we can reuse ds1307.c with
some modification.

I agree. The driver already supports some variants. Adding one more
should not hurt. See 97f902b7be4dd6ba03c6aa8d3400783ed687ebd1 for an
example which added ds3231 support.

quoted

But if I look at the drivers present in drivers/rtc folder. Most
of them looks similar but still there are different drivers for
different chips.

Yes, it probably could be cleaned up if somebody had the

time/hardware.

quoted

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Please suggest which way is more preferred: modifying existing
drivers(of different manufacturer) or writing new driver.

Ususally avoiding code duplication is good, it reduces maintenance
burden. However, if adding the support turns out to make the
original code unreadable or hard to follow, a new driver might be
justified. This is why it is important to understand the differences
of the chip as a first step. (I have the feeling, that modifying is
the way to go here, though).

I will explore possibility of using ds1307 driver for this.

=20
Has there been any movement here?