On Mon, Mar 18, 2019 at 3:04 PM Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx> wrote: > On Mon, Mar 18, 2019 at 09:30:53AM +0100, Linus Walleij wrote: > > This adds support for setting the flag bit "write allocate > > override" to the L210 variant. > > > > The "write allocate override" bit is used on the Nomadik STn8815 > > and is necessary to properly make use of the L210 cache on that > > machine without sporadic crashes. > > > > After this the platform can boot and run without any out-of-tree > > patches. > > This is not something that should be done by the kernel but by the > firmware - needing this bit set is a basic requirement of having > the caches enabled, and if (eg) the boot loader enables the caches > it too will suffer this problem. I see your point. This U-Boot port does not enable the cache, I guess because it was a bit unusual for ARM926EJ-S machines to have L2 cache at the time, and I remember U-Boot was not using L2CC for a long time (maybe still not?). The Nomadik was unstable for years and then I looked at the outoftree vendor kernel and saw that it sets this bit and since I did that it has been rock solid. I can of course try to recompile and reflash the U-Boot for this board but it is stored in NAND flash and if I break it, ugh, I have toasted this board and I only have one. So I'm scared about that. I have been carrying this as an out-of-tree patch for years and I can of course continue to do so, I just felt it was a bit sad so I tried to diet down the previous patch to the single bit the Nomadik needs to set up for it's L2CC to work. Yours, Linus Walleij
