Openmoko Bug #2180: stable-tracking: 'rxserr' UART messages

Openmoko Public Trac bugs at
Thu Jan 29 11:22:07 CET 2009

#2180: stable-tracking: 'rxserr' UART messages
 Reporter:  laforge          |          Owner:  openmoko-kernel         
     Type:  defect           |         Status:  new                     
 Priority:  high             |      Milestone:  FSO                     
Component:  System Software  |        Version:                          
 Severity:  major            |       Keywords:  gps s3x24xx_serial rxerr
 Haspatch:  0                |      Blockedby:                          
Estimated:                   |    Patchreview:                          
 Blocking:                   |   Reproducible:                          

Comment(by andy):

 I was thinking about this on and off the last days.

 Harald, what drivers do you have up on your non-GTAxx device?  I guess we
 can rule out Glamo for a start, so Glamo MMC.  What else can we know that
 it isn't then?  We can also rule out SDIO and AR6000 WLAN?  You probably
 don't have FIQ / HDQ up?  USB / Ethernet over USB is up?

 I had two ideas about mapping latency, first was to set all IRQs as FIQ,
 log the request time immediately, and if necessary do some magic about
 also having the IRQ dealt with as normal IRQ.  In the normal IRQ, we add
 code to also log the time it was finally serviced.  This would give 100%
 view of genuine latencies incorporating priority blocking relationship.

 Since that's a whole project in itself, I had another idea to make some
 macros and apply them to ISR entry and exit, maybe at platform, to simply
 log IRQ duration without capturing the relationship between that and other

 But neither are simple as the ARM920T does not have a CPU cycle counter
 register, so we need to study timers and debug that, etc.

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