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* Serial: bug in 8250.c when handling PCI or other level triggers
@ 2005-12-14 15:23 Alan Cox
  2005-12-14 16:07 ` Meelis Roos
  2005-12-14 16:55 ` Russell King
  0 siblings, 2 replies; 24+ messages in thread
From: Alan Cox @ 2005-12-14 15:23 UTC (permalink / raw)
  To: rmk, linux-kernel

The receive_chars function is designed to handle the case where the port
is jammed full on by aborting after 256 characters in one IRQ.
Unfortunately the author of this code forgot that some systems are level
triggered. On these systems the IRQ simply gets invoked again and the
count loop just makes the problem take longer to clear.

In the non level case it appears that a jam could leave the IRQ jammed
forever and ignored - the remaining bytes never appearing.

As far as I can see the code would actually need to clear the interrupt
enable and then restore it on a timer event or similar in order to get
the intended effect.

Alan


^ permalink raw reply	[flat|nested] 24+ messages in thread

end of thread, other threads:[~2006-01-09  8:54 UTC | newest]

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-12-14 15:23 Serial: bug in 8250.c when handling PCI or other level triggers Alan Cox
2005-12-14 16:07 ` Meelis Roos
2005-12-14 17:24   ` Russell King
2005-12-14 18:43     ` Meelis Roos
2005-12-21 15:24       ` Russell King
2005-12-21 20:33     ` Meelis Roos
2005-12-21 22:15       ` Russell King
2005-12-22 10:35         ` Meelis Roos
2005-12-22 13:07           ` Russell King
2005-12-22 13:19             ` Meelis Roos
2005-12-23  9:20             ` Meelis Roos
2005-12-23  9:33               ` Russell King
2005-12-23 10:05                 ` Meelis Roos
2005-12-23 10:41                   ` Russell King
2005-12-27 13:54                     ` Meelis Roos
2005-12-28 19:55                       ` Russell King
2005-12-29  8:11                         ` Meelis Roos
2006-01-08 23:24                           ` Antonio Vargas
2006-01-09  8:54                             ` Russell King
2005-12-14 22:29   ` Alan Cox
2005-12-15 19:00     ` Stuart MacDonald
2005-12-14 16:55 ` Russell King
2005-12-14 19:08   ` Alan Cox
2005-12-14 19:55     ` Russell King

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