Felix Radensky wrote: > Hi, Wolfgang > > Wolfgang Grandegger wrote: >> Felix Radensky wrote: >> >>> Hi, >>> >>> Almost all MPC85XX based systems have the compatible=:"fsl-i2c" in >>> respective >>> i2c device tree nodes. This causes FSL i2c driver to use the following >>> "backward >>> compatible" values: FSR=0x31 DFSR=0x10. This is regardless of CCB clock >>> frequency and i2c clock prescaler. >>> >>> On my custom MPC8536 based board with 432MHz CCB clock this results in >>> 65KHz i2c clock frequency (checked with scope). U-Boot correctly >>> configures >>> the clock to 400KHz. >>> >>> I've fixed the problem by modifying device tree to use different >>> compatible value, >>> similar to what socrates board does. Is this the right approach ? >>> >> >> Are you aware of the properties described in >> "Documentation/powerpc/dts-bindings/fsl/i2c.txt": >> >> http://lxr.linux.no/#linux+v2.6.32/Documentation/powerpc/dts-bindings/fsl/i2c.txt >> >> >> Wolfgang. >> >> > Sure, I'm aware of these properties. I've used > > compatible = "fsl,mpc8543-i2c", "fsl-i2c"; > clock-frequency = <400000>; > > for my custom board. > > I think, however, that device trees for FSL reference designs should use > them as well, to avoid setting i2c > clock to some strange values. I may be wrong, but I think most custom
The FSR=0x31 DFSR=0x10 are not strange values. They have been used in mainline kernels (< 2.6.30) for a long time. > board developers borrow from > reference device trees, so having a sane starting point would help. The trees provided by Freescale are usually based on older kernel version. Borrow from such trees is OK, but the project developers should use a recent kernel version for development. Wolfgang. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
