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

Hi Wolfram,=20

-----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.
=20
Hi Priyanka,
=20

quoted

Though register-set looks identical but features were different.

=20
Can you tell what exactly is different?

I will check both the devices data sheets again in detail and will get back=
 on this.

=20

quoted

And also manufacturer is different.

=20
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.
=20

quoted

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

=20
I agree. The driver already supports some variants. Adding one more
should not hurt. See 97f902b7be4dd6ba03c6aa8d3400783ed687ebd1 for an
example which added ds3231 support.
=20

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.

=20
Yes, it probably could be cleaned up if somebody had the time/hardware.
=20

quoted

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

=20
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).
=20

I will explore possibility of using ds1307 driver for this.


Thanks
Priyanka