On 28.05.21 08:11, Vignesh Raghavendra wrote: > Hi, > > On 5/28/21 11:09 AM, Tony Lindgren wrote: >> Hi Greg, Vignesh & Jan, >> >> * Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> [210513 14:17]: >>> On Tue, May 11, 2021 at 08:49:55PM +0530, Vignesh Raghavendra wrote: >>>> It is possible that RX TIMEOUT is signalled after RX FIFO has been >>>> drained, in which case a dummy read of RX FIFO is required to clear RX >>>> TIMEOUT condition. Otherwise, RX TIMEOUT condition is not cleared >>>> leading to an interrupt storm >>>> >>>> Cc: stable@xxxxxxxxxxxxxxx >>> >>> How far back does this need to go? What commit id does this fix? What >>> caused this to just show up now vs. previously? > > Sorry, I missed this reply. Issue was reported on AM65x SoC with custom > test case from Jan Kiszka that stressed UART with rapid baudrate changes > from 9600 to 4M along with data transfer. > > Based on the condition that led to interrupt storm, I inferred it to > affect all SoCs with 8250 OMAP UARTs. But that seems thats not the best > idea as seen from OMAP3 regression. > > Greg, > > Could you please drop the patch? Very sorry for the inconvenience.. > >> >> I just noticed this causes the following regression in Linux next when >> pressing a key on uart console after boot at least on omap3. This seems >> to happen on serial_port_in(port, UART_RX) in the quirk handling. >> >> Vignesh, it seems this quirk needs some soc specific flag added to >> it maybe? Or maybe UART_OMAP_RX_LVL register is not available for >> all the SoCs? >> > > Yes indeed :( > >> I think it's best to drop this patch until the issues are resolved, >> also there are some open comments above that might be answered by >> limiting this quirk to a specific range of SoCs :) >> > > Oops, I did test patch AM33xx assuming its equivalent to OMAP3, but UART > IP is quite different. I will respin the patch making sure, workaround > applies only to AM65x and K3 SoCs. > > Regards > Vignesh > What's the status here for AM65x? The issue remains present on that platform, and I was hoping to see a quick follow up that limit the fix to that target. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
