Re: [RFC] suggested fix for 83xx/85xx PowerPC UART break bug

[Kumar Gala]

On Jul 31, 2008, at 10:26 AM, Paul Gortmaker wrote:

> This is something I'd tripped over earlier, and wanted to follow up on
> to get an acceptable fix in for everyone's benefit before it falls  
> through
> the cracks again.
>
> There seems to be an issue with recent 83xx/85xx SOC UARTs, in which  
> a break
> triggers a short lived IRQ storm (hence killing any hope of using  
> SysRQ).
> The only fix I found to work was to just ignore the bogus events that
> had the associated signature bit set.
>
> This fix is what I was using against earlier kernels, but I hate to  
> add more
> board/arch specific ifdefs to files like 8250.c, so I'm wondering if
> anyone has any other suggestions before I simply end up cleaning up  
> the
> boardlist (now ppc is dead) and respinning the patch much as it is now
> and resending.

How did you test this or generate it?  I was thinking about this the  
other day and figured we need to try and track this down with the HW  
guys.  If we can generate a simple test I can try and run it through  
the various boards/parts we have and see which ones show the issue and  
which dont.

- k
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