Kumar Gala wrote: > > 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). OK, now it makes more sense to me even if I never thought that way. My intention was to allow Linux to use a *different* frequency as the bootloader by specifying the "clock-frequency" property. This would not be possible with a fixup by the bootloader. Wolfgang. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
