On Mon, Sep 8, 2014 at 2:20 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Monday 08 September 2014 13:38:04 Linus Walleij wrote: >> + of_property_read_u32(np, "cache-size", &size); >> + of_property_read_u32(np, "cache-sets", &sets); >> + >> + if (!size || !sets) >> + return; >> + >> + way_size = size / sets; > > Going back to this one: Isn't (size / sets) the set-size rather > than the way-size? > > After we discussed this on IRC, I had expected a calculation like > > set_size = size / sets; > ways = set_size / line_size; > way_size = size / ways; First: in this PB1176 case: set_size = 128K/8 = 16K ways = 16K/32 = 512 bytes way_size = 128K/512 = 128 bytes Well maybe it's the ARM reference manual internal lingo that is actually causing the confusion here. It will say something like: [19:17] Way-size 3’b000 = Reserved, internally mapped to 16KB 3’b001 = 16KB, this is the default value 3’b010 = 32KB 3’b011 = 64KB 3’b100 = 128KB 3’b101 = 256KB 3’b110 to 3’b111 = Reserved, internally mapped to 256 KB OK way-size ... is in the 16 thru 256KB range, which fits nicely with set size incidentally. And also corresponds to current comments in the code such as this from arch/arm/mach-realview/realview_pb1176.c: #ifdef CONFIG_CACHE_L2X0 /* * The PL220 needs to be manually configured as the hardware * doesn't report the correct sizes. * 128kB (16kB/way), 8-way associativity, event monitor and * parity enabled, ignore share bit, no force write allocate * Bits: .... ...0 0111 0011 0000 .... .... .... */ l2x0_init(__io_address(REALVIEW_PB1176_L220_BASE), 0x00730000, 0xfe000fff); #endif I can add a comment explaining that ARMs terminology does not match the academic terminology or something, and say that the thing we poke into "way-size" is actually "set size", if we agree that is what we're seeing here. Florian: what was your interpretation? Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html