Messages in this thread | | | Date | Wed, 16 Nov 2005 09:30:04 -0800 | From | George Anzinger <> | Subject | Re: [PATCH] backup timer for UARTs that lose interrupts (take 2) |
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Could you _please_ not put inline patches after the signature mark ("-- "). In my mailer (mozilla) this causes the patch to be greyed out and, more importantly, NOT included in a reply. This, in turn, makes it hard to comment on details in the patch.
Thanks George --
Alex Williamson wrote: > Hi Russell, > > I've revised the patch for this backup timer idea based on your > comments. Hopefully the restoring of the timer function to the default > serial8250_timeout is more obvious now. I also re-ordered some of the > conditions around the bug test to add further clarity. Please let me > know if you see any further issues with this patch. Patch below is > against 2.6.14-mm2. Here's the original patch description message: > > The patch below works around a minor bug found in the UART of the > remote management card used in many HP ia64 and parisc servers (aka the > Diva UARTs). The problem is that the UART does not reassert the THRE > interrupt if it has been previously cleared and the IIR THRI bit is > re-enabled. This can produce a very annoying failure mode when used as > a serial console, allowing a boot/reboot to hang indefinitely until an > RX interrupt kicks it into working again (ie. an unattended reboot could > stall). Paul Bame submitted a complete workaround for 2.4 kernels a few > years ago - http://lkml.org/lkml/2003/5/6/203. The problem has not been > as prevalent on the 2.6 serial driver, thus the solution below is > simplified to only insert a backup timeout to kick the UART when it gets > into trouble. This runs alongside the normal interrupt driven UART code > and has a longer period that the standard polling driver to reduce CPU > overhead. The detection test should be safe for all UARTs and the > backup timer can easily be extended to include other UARTs with similar > disorders. > > Please apply. Thanks, > > Alex >
-- George Anzinger george@mvista.com HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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