Re: imx-serial: RX DMA startup latency

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Jul 12, 2017 at 07:05:06PM -0300, Fabio Estevam wrote:
> From: Peter Senna Tschudin <peter.senna@collabora.com>
> 
> commit 4dec2f119e86f9c91e60cdd8f0cc057452e331a9 upstream.
> 
> 18a4208 introduced a change to reduce the RX DMA latency on the first reception
> when the serial port was opened for reading. However it was claiming a hardirq
> unsafe lock after a hardirq safe lock which is not allowed and causes lockdep
> to complain verbosely.
> 
> This patch changes the code to always start RX DMA earlier, instead of
> relying on the flags used to open the serial port removing the code that
> was looking for the serial file flags.
> 
> Cc: <stable@vger.kernel.org> #4.12.x
> Signed-off-by: Peter Senna Tschudin <peter.senna@collabora.com>
> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> ---
>  drivers/tty/serial/imx.c | 26 +++++---------------------
>  1 file changed, 5 insertions(+), 21 deletions(-)

What are you asking for here, for this to be added to the 4.12-stable
tree?

Or something else?

Please always be explicit...

thanks,

greg k-h