On Apr 8, 2009, at 1:27 PM, Wolfgang Grandegger wrote:
Grant Likely wrote:
On Wed, Apr 8, 2009 at 12:16 AM, Wolfgang Grandegger <wg@xxxxxxxxxxxxxx
> wrote:
Grant Likely wrote:
On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@xxxxxxxxxxxxxx
> wrote:
Preserve I2C clock settings for the Socrates MPC8544 board.
I had thought that the preserve-clocking property was intended for
older boards that don't currently have any method of getting the
clock
setting out of u-boot. Since Socrates is a new board, U-Boot
should
probably be made to fill in the real clock rate setting.
I'm not sure if I understand what you mean. If an old version of U-
Boot
on an old board sets the I2C clock, it can be used (inherited) by
Linux
using the property "preserve-clocking".
It is actually the customers choice to set the I2C clock in U-Boot
and
re-use it by Linux.
Setting it in the register != recording the value in the device tree.
I'm saying that since Socrates is a new board it should not use the
preserve-clocking dirty trick (and it is a dirty trick) because the
correct clocking data can be passed via the device tree.
Why should an old board then use it. "fsl, preserve-clocking" is a new
feature, like using "clock-frequency" and you have the choice to
explicitly set the clocking via device tree or inherit it from the
boot
loader. So far, a fixed FDR/DFRSS value (0x1031) was written to the
registers by Linux.
I think Grant's point is socrates is a new board with a new u-boot.
That u-boot should be able to set the clock-frequency property in
i2c. One assumes if you a clock-frequency property you wouldn't use
"fsl,preserve-clocking". (However -- its feasible they are mutually
exclusive).
- k
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