Stefan Roese <s...@denx.de> wrote: > On Tuesday 01 September 2009 10:57:52 Haavard Skinnemoen wrote: > > > Well, usually we run with IC on and with DC off, usually because > > > quite a number of drivers and other code do not use proper I/O > > > accessors yet, and/or because it's easier and nobody really cares. > > > For example on PowerPC, adding support for the data cache usually > > > gives only a minimal performance boost. This may be different on > > > other architectures. > > > > Ok, so the code is broken and nobody else cares? > > I wouldn't put it like this. The CFI driver assumes that the FLASH mapping is > not cached. This makes perfect sense in my point of view.
Yes, and it can do that safely because it specifically asks for an uncached address from map_physmem(). That part didn't actually change with the patch in question -- the problem is that the address returned by map_physmem() is now exposed through external interfaces -- it's not just an internal implementation detail anymore. > > I suppose I could disable the DC (which is a bit complicated, but > > possible), but that would just add to the already high cost (in terms > > of both code size and performance) of using common code (i.e. the CFI > > driver), so I'm leaning towards a custom flash driver instead. > > On some 440 platforms we configure the FLASH cached upon powerup, and disable > the caching after relocating to SDRAM. So when the CFI driver is started, the > FLASH is not cached any more, but we have the cache speedup upon relocation. That's what I want to do as well! And I can actually do that as long as the flash subsystem uses map_physmem() consistently. Haavard _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
