On 07/18/2018 12:05 PM, Mikko Perttunen wrote: > On 18.07.2018 14:33, Dmitry Osipenko wrote: >> On Friday, 13 July 2018 14:32:42 MSK David R. Piegdon wrote: >>> Hi, >>> a while back I sent a few mails regarding spurious interrupts in the >>> UARTA (hsuart) block of the Tegra2 SoC, when using the 8250 driver for >>> it instead of the hsuart driver. After going down a pretty deep >>> debugging/testing hole, I think I found a patch that fixes the issue. So >>> far testing in a reboot-cycle suggests that the error frequency dropped >>> from >3% of all reboots to at least <0.05% of all reboots. Tests >>> continue to run over the weekend. >>> >>> The patch below already is a second iteration; the first did not reset >>> the MCR or contain the lines below '// clear interrupts'. This resulted >>> in no more spurious interrupts, but in a few % of spurious interrupts >>> that were recovered the UART block did not receive any characters any >>> more. So further resetting was required to fully reacquire operational >>> state of the UART block. >>> >>> I'd love any comments/suggestions on this! >>> >> >> I'm wondering whether later Tegra's have that issue as well, maybe Mikko >> knows? > > My understanding is that the issue is on all generations. > Hi, its great to get some feedback here! Disclaimer: So far I only know that my specific hardware- and software-combination sees this issue. But I do see it across multiple devices. Also I only have Tegra2 hardware, so I am completely unsure if other Tegra CPUs are affected. *I am still waiting for confirmation from anyone else, if this is a real issue*. For all that I know, it could be that we muxed some lines wrongly which results in some core power rails being screwed, or anything like this. So if you actually see this issue, please let me know! >> >> Instead of #ifdef-ing T20 in the code, there probably should be some >> kind of a >> port flag. Please send a proper patch and follow suggestions from tty/ >> maintainers.> > Yep - if possible to do in a tegra-specific callback, that would be > nice, but I'm not sure if that's possible. Due to above reasons, this was just an initial request for comments. I will implement your suggestions over the next few days. Thanks! David -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
