Re: [RFC][PATCH 4/4] RTC: SMBus support for the M41T80,

Jean Delvare
2008-05-08T07:46:20Z

Hi David,

On Wed, 7 May 2008 16:25:20 -0700, David Brownell wrote:
> On Wednesday 07 May 2008, Maciej W. Rozycki wrote:
> > Well, I have to admit what I know in detail about I2C and how it is
> > handled by Linux is what I gathered over the last weekend. The idea of
> > the change, given a change had to be done, was to make the driver a bit
> > more flexible. Of all the I2C RTC drivers this seems to be one of the two
> > only that require *both* I2C *and* SMBus functionality in the driving
> > controller at the same time. With this change in place only either of the
> > two is needed. Please correct me if I am wrong.
>
> It checks for "I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE_DATA" which is
> admittedly odd. Because if it can do I2C, it can assuredly do
> that minor subset of SMBus. (Modulo bugs in how drivers end up
> reporting their capabilities.)

Not totally correct, see my reply somewhere else in this thread.

> > (...)
> > I think a pair of functions called i2c_smbus_read_i2c_byte_data() and
> > i2c_smbus_write_i2c_byte_data() could be added to the core though.
>
> Too late. Those calls have been in the I2C core for a long
> time now. ;)

No, we don't have any function named that way. Not that I think that
these names would be appropriate, though. I'd rather have
i2c_smbus_read_i2c_block_emul() for example.

--
Jean Delvare

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