Am Di., 11. Sep. 2018 um 16:30 Uhr schrieb Stefan Roese sr@denx.de:
On 11.09.2018 16:12, Daniel Schwierzeck wrote:
Am Mo., 10. Sep. 2018 um 07:34 Uhr schrieb Stefan Roese sr@denx.de:
Hi Daniel,
On 07.09.2018 19:02, Daniel Schwierzeck wrote:
Those functions are not needed during cache init and can be implemented in C. Only support the safe disabling of caches when this is required for booting an OS. Reenabling caches is much harder to implement if an optional coherency manager must be supported. As there is no real use-case anyway, dcache_enable is implemented with an error message.
Signed-off-by: Daniel Schwierzeck daniel.schwierzeck@gmail.com
Many thanks for working on this. I'll be doing some more test later this week using this series. One comment though directly:
A few weeks ago I wanted to enable the "cache" cmd (CMD_CACHE) on my MT7688 MIPS platform. Unfortunately some I-Cache functions are missing for this:
building ... cmd/built-in.o: In function `do_icache': cmd/cache.c:(.text.do_icache+0x48): undefined reference to `icache_disable' cmd/cache.c:(.text.do_icache+0x68): undefined reference to `icache_enable' cmd/cache.c:(.text.do_icache+0x88): undefined reference to `icache_status' Makefile:1350: recipe for target 'u-boot' failed
Would it be possible to add those functions as well to this series (or some follow-up patch)? Using the cache cmd can be quite helpful while testing / debugging.
The problem is that you can't independently disable I-Cache and D-Cache on MIPS.
Why is this the case? Can't the I-Cache be disabled at all? Or is it just not possible (or complex) while running with I-Cache enabled?
you can only configure the "Cache Coherency Algorithm" in Coprocessor 0 Config register. This setting affects I-Cache and D-Cache at once.
Maybe a workaround for icache_[en|dis]able could be to shift the instruction pointer from KSEG0 to KSEG1. This is the same principle you had with ddr_calibrate() in your first iteration of MT76xx patch series.
I could add them as dummy functions or with the same implementation as dcache_*
That's perhaps a pragmatic work-around - if the I-Cache can't be disabled at all.
Thanks, Stefan
-- - Daniel