On Mon, Jan 22, 2018 at 01:07:19PM +0000, James Hogan wrote:

Hi stable maintainers,

On Sun, Oct 29, 2017 at 04:27:21PM +0100, Jonas Gorski wrote:

...

Since commit aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers"), the port's default FCR value isn't used in serial8250_do_set_termios anymore, but copied over once in serial8250_config_port and then modified as needed.

Unfortunately, serial8250_config_port will never be called if the port is shared between kernel and userspace, and the port's flag doesn't have UPF_BOOT_AUTOCONF, which would trigger a serial8250_config_port as well.

This causes garbled output from userspace:

[ 5.220000] random: procd urandom read with 49 bits of entropy available ers [kee

Fix this by forcing it to be configured on boot, resulting in the expected output:

[ 5.250000] random: procd urandom read with 50 bits of entropy available Press the [f] key and hit [enter] to enter failsafe mode Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level

Fixes: aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers") Signed-off-by: Jonas Gorski jonas.gorski@gmail.com

Please can this patch be applied to stable branches 3.17+. It is now merged into mainline as commit 0a5191efe06b ("MIPS: AR7: ensure the port type's FCR value is used").

Commit b084116f8587 ("MIPS: AR7: Ensure that serial ports are properly set up") is a prerequisite for it to apply cleanly, but is already tagged for stable.

Now snuck into this round of stable -rc review :)

thanks,

greg k-h