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

From: Wolfram Sang <[email-masked]>
Date: Thu, 10 Mar 2011 09:54:14 +0100

Hi Priyanka,

> Though register-set looks identical but features were different.

Can you tell what exactly is different?

> 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.

> 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.

> 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.

> 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).

Regards,

   Wolfram

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