[PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm

[Greg Kroah-Hartman]

On Fri, May 28, 2021 at 11:41:36AM +0530, Vignesh Raghavendra wrote:
> Hi,
> 
> On 5/28/21 11:09 AM, Tony Lindgren wrote:
> > Hi Greg, Vignesh & Jan,
> > 
> > * Greg Kroah-Hartman <gregkh at linuxfoundation.org> [210513 14:17]:
> >> On Tue, May 11, 2021 at 08:49:55PM +0530, Vignesh Raghavendra wrote:
> >>> It is possible that RX TIMEOUT is signalled after RX FIFO has been
> >>> drained, in which case a dummy read of RX FIFO is required to clear RX
> >>> TIMEOUT condition. Otherwise, RX TIMEOUT condition is not cleared
> >>> leading to an interrupt storm
> >>>
> >>> Cc: stable at vger.kernel.org
> >>
> >> How far back does this need to go?  What commit id does this fix?  What
> >> caused this to just show up now vs. previously?
> 
> Sorry, I missed this reply. Issue was reported on AM65x SoC with custom
> test case from Jan Kiszka that stressed UART with rapid baudrate changes
> from 9600 to 4M along with data transfer.
> 
> Based on the condition that led to interrupt storm, I inferred it to
> affect all SoCs with 8250 OMAP UARTs. But that seems thats not the best
> idea as seen from OMAP3 regression.
> 
> Greg,
> 
> Could you please drop the patch? Very sorry for the inconvenience..

Now reverted, thanks.

greg k-h