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.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1c05bf6c0262f946571a37678250193e46b1ff0f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025102740-stiffly-recolor-e335@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 1c05bf6c0262f946571a37678250193e46b1ff0f Mon Sep 17 00:00:00 2001 From: Hugo Villeneuve hvilleneuve@dimonoff.com Date: Mon, 6 Oct 2025 10:20:02 -0400 Subject: [PATCH] serial: sc16is7xx: remove useless enable of enhanced features

Commit 43c51bb573aa ("sc16is7xx: make sure device is in suspend once probed") permanently enabled access to the enhanced features in sc16is7xx_probe(), and it is never disabled after that.

Therefore, remove re-enable of enhanced features in sc16is7xx_set_baud(). This eliminates a potential useless read + write cycle each time the baud rate is reconfigured.

Fixes: 43c51bb573aa ("sc16is7xx: make sure device is in suspend once probed") Cc: stable stable@kernel.org Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Link: https://patch.msgid.link/20251006142002.177475-1-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 1a2c4c14f6aa..c7435595dce1 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -588,13 +588,6 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud) div /= prescaler; }

- /* Enable enhanced features */ - sc16is7xx_efr_lock(port); - sc16is7xx_port_update(port, SC16IS7XX_EFR_REG, - SC16IS7XX_EFR_ENABLE_BIT, - SC16IS7XX_EFR_ENABLE_BIT); - sc16is7xx_efr_unlock(port); - /* If bit MCR_CLKSEL is set, the divide by 4 prescaler is activated. */ sc16is7xx_port_update(port, SC16IS7XX_MCR_REG, SC16IS7XX_MCR_CLKSEL_BIT,