Re: Spurious serial console interrupts

2016-04-13 Thread Visa Hankala
On Wed, Apr 13, 2016 at 06:15:46AM +, Miod Vallat wrote: > > It should be latched, at least on modern 16550-like UARTs. From > > a PC16550D datasheet: > > Keep in mind that com(4) is intended to support 16450 chips, which have > no FIFO. I believe that the current ordering of the operations

Re: Spurious serial console interrupts

2016-04-13 Thread Miod Vallat
> It should be latched, at least on modern 16550-like UARTs. From > a PC16550D datasheet: Keep in mind that com(4) is intended to support 16450 chips, which have no FIFO. I believe that the current ordering of the operations is needed to correctly support them, so you might want to decide at

Re: Spurious serial console interrupts

2016-04-12 Thread Visa Hankala
On Tue, Apr 12, 2016 at 05:03:39PM +0200, Mark Kettenis wrote: > > On Fri, Apr 08, 2016 at 12:16:03PM +, Visa Hankala wrote: > > > Every now and then I see "spurious interrupt 34" messages on octeon > > > serial console. The root cause seems to be in comstart() which enables > > > the TX

Re: Spurious serial console interrupts

2016-04-12 Thread Mark Kettenis
> Date: Tue, 12 Apr 2016 13:12:42 + > From: Visa Hankala > > On Fri, Apr 08, 2016 at 12:16:03PM +, Visa Hankala wrote: > > Every now and then I see "spurious interrupt 34" messages on octeon > > serial console. The root cause seems to be in comstart() which enables > >

Re: Spurious serial console interrupts

2016-04-12 Thread Martin Pieuchot
On 12/04/16(Tue) 15:31, Mike Belopuhov wrote: > On 12 April 2016 at 15:12, Visa Hankala wrote: > > On Fri, Apr 08, 2016 at 12:16:03PM +, Visa Hankala wrote: > >> Every now and then I see "spurious interrupt 34" messages on octeon > >> serial console. The root cause seems to

Re: Spurious serial console interrupts

2016-04-12 Thread Mike Belopuhov
On 12 April 2016 at 15:12, Visa Hankala wrote: > On Fri, Apr 08, 2016 at 12:16:03PM +, Visa Hankala wrote: >> Every now and then I see "spurious interrupt 34" messages on octeon >> serial console. The root cause seems to be in comstart() which enables >> the TX holding

Re: Spurious serial console interrupts

2016-04-12 Thread Visa Hankala
On Fri, Apr 08, 2016 at 12:16:03PM +, Visa Hankala wrote: > Every now and then I see "spurious interrupt 34" messages on octeon > serial console. The root cause seems to be in comstart() which enables > the TX holding register empty interrupt before writing data to the TX > register. If the

Spurious serial console interrupts

2016-04-08 Thread Visa Hankala
Every now and then I see "spurious interrupt 34" messages on octeon serial console. The root cause seems to be in comstart() which enables the TX holding register empty interrupt before writing data to the TX register. If the register is empty initially, the early enabling can trigger a premature