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This would lead me to believe that cpuidle is entered while > irq_work from a directly preceeding printk (from outside cpuidle) was > pending and caused a problem. > > Does this hack really work reliably, without using keep_bootcon or any > other patches? I went back and started again on top of next-20260825. Vanilla next-20260825 is failing on Tegra20 about 19 boots out of 20. With hack 1 and hack 2 it is also pretty much 100% failure with 20 boots. However, with the latest hack it is passing 100% (20 out of 20 boots). So yes I say that this works reliably. > Also, although this hack will avoid queuing irq_work from within > cpuidle, it does not prevent the 8250 console driver from queuing > irq_work for MSR handling during atomic printing. There is no generic > console callback to deal with that (other than suspending the console). > > I suspect it is a general irq_work problem on tegra regarding > suspend/cpuidle. Really the problem should be fixed there. But I would > need hardware to investigate the issue. I am seeing this on Tegra20 and Tegra30 boards, which are the oldest we test and so difficult to get hardware for these. So there is the following code in the cpuidle-tegra.c driver ... if (tegra_pending_sgi()) { /* * CPU got local interrupt that will be lost after GIC's * shutdown because GIC driver doesn't save/restore the * pending SGI state across CPU cluster PM. Abort and retry * next time. */ atomic_set(&tegra_abort_flag, 1); } So may be interrupts are getting lost? > As for this 8250 "switch to nbcon" series, I am uncertain how to > proceed. Is it really printk's job (and, by extension, the console > driver's job) to decipher when it is allowed to queue irq_work? Yes understand. I am not sure if it is possible to opt out of this switch for old legacy platforms like this? Jon -- nvpublic