On Sun, 24 Jul 2016, Robert P. J. Day wrote:

working with MPC83xx at the moment, i'm used to seeing "CONFIG_QE" all over the place, but what means "CONFIG_U_QE"? it seems like some sort of freescale special feature, but i can't figure it out.

just to follow up my earlier question, i can see this in drivers/Makefile:

obj-$(CONFIG_QE) += qe/ obj-$(CONFIG_U_QE) += qe/

and, further, i can see this in drivers/qe/Makefile:

obj-$(CONFIG_QE) += qe.o uccf.o uec.o uec_phy.o obj-$(CONFIG_U_QE) += qe.o obj-$(CONFIG_OF_LIBFDT) += fdt.o

so, clearly, setting CONFIG_U_QE represents *not* compiling in a number of files, but i'm still unclear on the fundamental, underlying difference in architecture or design between QE and U_QE.

oh, and i also notice that while fdt.c is selected, the entire contents of that source file are wrapped in:

#include <common.h> #include <libfdt.h> #include <fdt_support.h> #include <fsl_qe.h>

#ifdef CONFIG_QE

... massive snip ...

#endif

so, obviously(?), device trees are not relevant for whatever U_QE represents?

rday