stable-1.9: cherry-pick "Revert trace enable commits, fix DEBUG_TRACE_PTR() macro so it can be used early #4760" #4788
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As reported in thesofproject#4759, thesofproject#4636 and a few others linked from there. Signed-off-by: Marc Herbert <marc.herbert@intel.com> (cherry picked from commit 3ff1dc0)
This reverts commit 7df3674. This restores the ability to use CONFIG_TRACEM (copy everything to mailbox) without crashing, in other words it fixes thesofproject#4699 This also fixes the other DSP panic thesofproject#4676 and removes the need for logical changes in thesofproject#4678, which can be reverted too. commit 7df3674 ("trace: enable trace after it is ready") was meant to fix a crash when tr_xxx() was used early. However I've used very early tracing for months and it never caused any crash (see thesofproject#4334) I tried adding a tr_err() statement immediately after trace_init(sof) in primary_core_init() and it works just fine. primary_core_init() runs extremely early so I don't think it's too demanding not to use an tr_XXX() before the trace even exists. The reverted commits confused initializing and enabling. Reproduction thesofproject#4683 did not seem to demonstrate anything obvious, there's not even a link to a failed test run. I don't understand how playing with spin locks is relevant to this. Later, reproduction thesofproject#4759 finally demonstrated the real issue: through DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal debug circumstances specific to the original author) before the trace is initialized. The previous commit in this series fixes that by simply guarding it with if(trace_get()) -------- I am _not_ pretending that these reverts make the tracing code bug-free and perfect again, absolutely not and very far from it. I'm merely saying that: - The first reverted commit caused at least two regressions: thesofproject#4676 and thesofproject#4699 - These two commits added yet another variable (time) in an already complex situation with an already existing combinatorial "explosion": compile-time Kconfigs, run-time settings, platform-specific bugs (thesofproject#4333, thesofproject#4573, ...), various races, mbox + DMA, different DMA engines, Zephyr vs XTOS, etc. - Last but not least, we don't want to invest in making the exist trace implementation better. We want to switch to the Zephyr implementation instead So let's go back to a previous known good state, I mean _relatively_ good and stay there if we can. Signed-off-by: Marc Herbert <marc.herbert@intel.com> (cherry picked from commit f2c13f5)
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https://sof-ci.01.org/sofpr/PR4788/build10400/devicetest is all green. |
keyonjie
approved these changes
Nov 2, 2021
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100% clean cherry-pick of #4760