Re: [PATCH] i2c-qoriq: modified compatibility for correct prescaler

On Tue, Dec 23, 2014 at 02:23:01PM +0100, Valentin Longchamp wrote:

Wolfgang, Scott,

Wolfram, please.

quoted

What is then the agreement here ? Add a clock-div to the device trees ? Or do
something similar to  mpc_i2c_get_sec_cfg_8xxx() ?

I think the clock-div property is better according to Freescale's AN 2919
section 3.1 Source clock. All the source clocks are fixed (with a clock-div of 2
in case of mpc8536/43/45/47/48/67/68/72, plus p2020) except for the mpc8533/44
where it can be 2 or 3, and that's what mpc_i2c_get_sec_cfg_8xxx() determines.

So mpc_i2c_get_sec_cfg_8xxx() should remain the exception and the other
prescaler values should be derived from an additional clock-div that must be
added in the respective device trees (at least for the qoriq devices, because
for instance mpc8543 already has the correct prescaler thanks to
mpc_i2c_data_8543 from i2c-mpc.c).

Do you have an opinion on the above ?

I don't mind. I'll leave it to PowerPC experts to judge if a new binding
is apropriate or reading SVR is the way to go. If it is going to be a
new binding, then please look around before if there is already
something similar around...

On Tue, 2014-12-23 at 14:49 +0100, Wolfram Sang wrote:

On Tue, Dec 23, 2014 at 02:23:01PM +0100, Valentin Longchamp wrote:

quoted

Wolfgang, Scott,

Wolfram, please.

quoted

quoted

What is then the agreement here ? Add a clock-div to the device trees ? Or do
something similar to  mpc_i2c_get_sec_cfg_8xxx() ?

I think the clock-div property is better according to Freescale's AN 2919
section 3.1 Source clock. All the source clocks are fixed (with a clock-div of 2
in case of mpc8536/43/45/47/48/67/68/72, plus p2020) except for the mpc8533/44
where it can be 2 or 3, and that's what mpc_i2c_get_sec_cfg_8xxx() determines.

So mpc_i2c_get_sec_cfg_8xxx() should remain the exception and the other
prescaler values should be derived from an additional clock-div that must be
added in the respective device trees (at least for the qoriq devices, because
for instance mpc8543 already has the correct prescaler thanks to
mpc_i2c_data_8543 from i2c-mpc.c).

Do you have an opinion on the above ?

I don't mind. I'll leave it to PowerPC experts to judge if a new binding
is apropriate or reading SVR is the way to go. If it is going to be a
new binding, then please look around before if there is already
something similar around...

I'd rather use SVR so things work with existing device trees.

-Scott