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

On Fri, May 28, 2021 at 11:41:36AM +0530, Vignesh Raghavendra wrote:

Hi,

On 5/28/21 11:09 AM, Tony Lindgren wrote:

quoted

Hi Greg, Vignesh & Jan,

* Greg Kroah-Hartman [off-list ref] [210513 14:17]:

quoted

On Tue, May 11, 2021 at 08:49:55PM +0530, Vignesh Raghavendra wrote:

quoted

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@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