On 04/13/2016 04:11 AM, Sekhar Nori wrote: > On Wednesday 13 April 2016 05:30 AM, Peter Hurley wrote: > >>>> - generates spurious uart interrupt for every rx dma transaction >>>> (ie., necessitates acking every UART interrupt, even UART_IIR_NO_INT) >>>> _Even with this workaround_, it still generates spurious interrupt >>>> warning >>>> which shuts off interrupts for several ms while logging the error >>>> message to the console, virtually guaranteeing lost data. >>> >>> as I wrote in my other email I think RDI should be disabled with DMA >> >> >> I'll test to see if disabling RDI eliminates the UART_IIR_NO_INT spurious >> interrupts.
Ok; disabling UART_IER_RDI eliminates the UART_IIR_NO_INT spurious interrupts. However, disabling RDI disables RX timeout as well, so data just sits in the RX fifo with no way to get it out. AFAICT that's a showstopper. >>> according the Intel manual and I *think* someone here reported that >>> they see the same problem. >> >> Let's confirm with the Intel folks that this is true, which would argue >> for using the omap-style rx dma flow. > > Andy Shevchenko pointed this out here: https://lkml.org/lkml/2016/2/23/588 which Andy noted as well: On 02/23/2016 08:56 AM, Andy Shevchenko wrote: > The problem is that we have no separate bit to control timeout > interrupts from UART.
