soc: qcom: rpmh-rsc: Kill cmd_cache and find_match() with fire
The "cmd_cache" in RPMH wasn't terribly sensible. Specifically:
- The current code doesn't really detect "conflicts" properly any case
where the sequence being checked has more than one entry. One
simple way to see this in the current code is that if cmd[0].addr
isn't found then cmd[1].addr is never checked.
- The code attempted to use the "cmd_cache" to update an existing
message in a sleep/wake TCS with new data. The goal appeared to be
to update part of a TCS while leaving the rest of the TCS alone. We
never actually do this. We always fully invalidate and re-write
everything.
- If/when we try to optimize things to not fully invalidate / re-write
every time we update the TCSes we'll need to think it through very
carefully. Specifically requirement of find_match() that the new
sequence of addrs must match exactly the old sequence of addrs seems
inflexible. It's also not documented in rpmh_write() and
rpmh_write_batch(). In any case, if we do decide to require updates
to keep the exact same sequence and length then presumably the API
and data structures should be updated to understand groups more
properly. The current algorithm doesn't really keep track of the
length of the old sequence and there are several boundary-condition
bugs because of that. Said another way: if we decide to do
something like this in the future we should start from scratch and
thus find_match() isn't useful to keep around.
This patch isn't quite a no-op. Specifically:
- It should be a slight performance boost of not searching through so
many arrays.
- The old code would have done something useful in one case: it would
allow someone calling rpmh_write() to override the data that came
from rpmh_write_batch(). I don't believe that actually happens in
reality.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Maulik Shah <mkshah@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Tested-by: Maulik Shah <mkshah@codeaurora.org>
Link: https://lore.kernel.org/r/20200413100321.v4.5.I6d3d0a3ec810dc72ff1df3cbf97deefdcdeb8eef@changeid
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>