The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

7090abd6ad06 ("serial: 8250_lpss: Use 16B DMA burst with Elkhart Lake") 2cb3315107b5 ("serial: 8250_lpss: Enable PSE UART Auto Flow Control")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7090abd6ad0610a144523ce4ffcb8560909bf2a8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= ilpo.jarvinen@linux.intel.com Date: Tue, 8 Nov 2022 14:19:51 +0200 Subject: [PATCH] serial: 8250_lpss: Use 16B DMA burst with Elkhart Lake MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Configure DMA to use 16B burst size with Elkhart Lake. This makes the bus use more efficient and works around an issue which occurs with the previously used 1B.

The fix was initially developed by Srikanth Thokala and Aman Kumar. This together with the previous config change is the cleaned up version of the original fix.

Fixes: 0a9410b981e9 ("serial: 8250_lpss: Enable DMA on Intel Elkhart Lake") Cc: stable@vger.kernel.org # serial: 8250_lpss: Configure DMA also w/o DMA filter Reported-by: Wentong Wu wentong.wu@intel.com Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Link: https://lore.kernel.org/r/20221108121952.5497-4-ilpo.jarvinen@linux.intel.co... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c index 7d9cddbfef40..0e43bdfb7459 100644 --- a/drivers/tty/serial/8250/8250_lpss.c +++ b/drivers/tty/serial/8250/8250_lpss.c @@ -174,6 +174,8 @@ static int ehl_serial_setup(struct lpss8250 *lpss, struct uart_port *port) */ up->dma = dma;

+ lpss->dma_maxburst = 16; + port->set_termios = dw8250_do_set_termios;

return 0;