FAILED: patch "[PATCH] serial: sc16is7xx: remove useless enable of enhanced features" failed to apply to 6.1-stable tree

List overview All Threads
Download

newer

older

[PATCH 01/25] media: i2c: ov01a10:...

FAILED: patch "[PATCH] xhci: dbc:...

gregkh＠linuxfoundation.org

27 Oct 2025 27 Oct '25

7:25 a.m.

The patch below does not apply to the 6.1-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-6.1.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 '2025102739-fable-reroute-e6a6@gregkh' --subject-prefix 'PATCH 6.1.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,

Show replies by date

Sasha Levin

27 Oct 27 Oct

6:53 p.m.

New subject: [PATCH 6.1.y 1/4] serial: sc16is7xx: remove unused to_sc16is7xx_port macro

From: Hugo Villeneuve hvilleneuve@dimonoff.com

[ Upstream commit 22a048b0749346b6e3291892d06b95278d5ba84a ]

This macro is not used anywhere.

Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Link: https://lore.kernel.org/r/20230905181649.134720-1-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Stable-dep-of: 1c05bf6c0262 ("serial: sc16is7xx: remove useless enable of enhanced features") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/sc16is7xx.c | 1 - 1 file changed, 1 deletion(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 63573ef8b9142..a187ae217fc4c 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -358,7 +358,6 @@ static struct uart_driver sc16is7xx_uart = { static void sc16is7xx_ier_set(struct uart_port *port, u8 bit); static void sc16is7xx_stop_tx(struct uart_port *port);

-#define to_sc16is7xx_port(p,e) ((container_of((p), struct sc16is7xx_port, e))) #define to_sc16is7xx_one(p,e) ((container_of((p), struct sc16is7xx_one, e)))

static u8 sc16is7xx_port_read(struct uart_port *port, u8 reg)

-- 2.51.0

Sasha Levin

6:53 p.m.

New subject: [PATCH 6.1.y 2/4] serial: sc16is7xx: reorder code to remove prototype declarations

From: Hugo Villeneuve hvilleneuve@dimonoff.com

[ Upstream commit 2de8a1b46756b5a79d8447f99afdfe49e914225a ]

Move/reorder some functions to remove sc16is7xx_ier_set() and sc16is7xx_stop_tx() prototypes declarations.

No functional change.

sc16is7xx_ier_set() was introduced in commit cc4c1d05eb10 ("sc16is7xx: Properly resume TX after stop").

Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Link: https://lore.kernel.org/r/20231221231823.2327894-16-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Stable-dep-of: 1c05bf6c0262 ("serial: sc16is7xx: remove useless enable of enhanced features") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/sc16is7xx.c | 75 ++++++++++++++++------------------ 1 file changed, 36 insertions(+), 39 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index a187ae217fc4c..f87fcde9a3d49 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -355,9 +355,6 @@ static struct uart_driver sc16is7xx_uart = { .nr = SC16IS7XX_MAX_DEVS, };

-static void sc16is7xx_ier_set(struct uart_port *port, u8 bit); -static void sc16is7xx_stop_tx(struct uart_port *port); - #define to_sc16is7xx_one(p,e) ((container_of((p), struct sc16is7xx_one, e)))

static u8 sc16is7xx_port_read(struct uart_port *port, u8 reg) @@ -415,6 +412,42 @@ static void sc16is7xx_power(struct uart_port *port, int on) on ? 0 : SC16IS7XX_IER_SLEEP_BIT); }

+static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit) +{ + struct sc16is7xx_port *s = dev_get_drvdata(port->dev); + struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); + + lockdep_assert_held_once(&port->lock); + + one->config.flags |= SC16IS7XX_RECONF_IER; + one->config.ier_mask |= bit; + one->config.ier_val &= ~bit; + kthread_queue_work(&s->kworker, &one->reg_work); +} + +static void sc16is7xx_ier_set(struct uart_port *port, u8 bit) +{ + struct sc16is7xx_port *s = dev_get_drvdata(port->dev); + struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); + + lockdep_assert_held_once(&port->lock); + + one->config.flags |= SC16IS7XX_RECONF_IER; + one->config.ier_mask |= bit; + one->config.ier_val |= bit; + kthread_queue_work(&s->kworker, &one->reg_work); +} + +static void sc16is7xx_stop_tx(struct uart_port *port) +{ + sc16is7xx_ier_clear(port, SC16IS7XX_IER_THRI_BIT); +} + +static void sc16is7xx_stop_rx(struct uart_port *port) +{ + sc16is7xx_ier_clear(port, SC16IS7XX_IER_RDI_BIT); +} + static const struct sc16is7xx_devtype sc16is74x_devtype = { .name = "SC16IS74X", .nr_gpio = 0, @@ -891,42 +924,6 @@ static void sc16is7xx_reg_proc(struct kthread_work *ws) sc16is7xx_reconf_rs485(&one->port); }

-static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit) -{ - struct sc16is7xx_port *s = dev_get_drvdata(port->dev); - struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); - - lockdep_assert_held_once(&port->lock); - - one->config.flags |= SC16IS7XX_RECONF_IER; - one->config.ier_mask |= bit; - one->config.ier_val &= ~bit; - kthread_queue_work(&s->kworker, &one->reg_work); -} - -static void sc16is7xx_ier_set(struct uart_port *port, u8 bit) -{ - struct sc16is7xx_port *s = dev_get_drvdata(port->dev); - struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); - - lockdep_assert_held_once(&port->lock); - - one->config.flags |= SC16IS7XX_RECONF_IER; - one->config.ier_mask |= bit; - one->config.ier_val |= bit; - kthread_queue_work(&s->kworker, &one->reg_work); -} - -static void sc16is7xx_stop_tx(struct uart_port *port) -{ - sc16is7xx_ier_clear(port, SC16IS7XX_IER_THRI_BIT); -} - -static void sc16is7xx_stop_rx(struct uart_port *port) -{ - sc16is7xx_ier_clear(port, SC16IS7XX_IER_RDI_BIT); -} - static void sc16is7xx_ms_proc(struct kthread_work *ws) { struct sc16is7xx_one *one = to_sc16is7xx_one(ws, ms_work.work);

-- 2.51.0

Sasha Levin

6:53 p.m.

New subject: [PATCH 6.1.y 3/4] serial: sc16is7xx: refactor EFR lock

From: Hugo Villeneuve hvilleneuve@dimonoff.com

[ Upstream commit 0c84bea0cabc4e2b98a3de88eeb4ff798931f056 ]

Move common code for EFR lock/unlock of mutex into functions for code reuse and clarity.

With the addition of old_lcr, move irda_mode within struct sc16is7xx_one to reduce memory usage: Before: /* size: 752, cachelines: 12, members: 10 */ After: /* size: 744, cachelines: 12, members: 10 */

Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Link: https://lore.kernel.org/r/20231221231823.2327894-17-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Stable-dep-of: 1c05bf6c0262 ("serial: sc16is7xx: remove useless enable of enhanced features") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/sc16is7xx.c | 106 ++++++++++++++++++--------------- 1 file changed, 57 insertions(+), 49 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index f87fcde9a3d49..c0c2c1450e88d 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -329,8 +329,9 @@ struct sc16is7xx_one { struct kthread_work reg_work; struct kthread_delayed_work ms_work; struct sc16is7xx_one_config config; - bool irda_mode; unsigned int old_mctrl; + u8 old_lcr; /* Value before EFR access. */ + bool irda_mode; };

struct sc16is7xx_port { @@ -412,6 +413,49 @@ static void sc16is7xx_power(struct uart_port *port, int on) on ? 0 : SC16IS7XX_IER_SLEEP_BIT); }

+/* + * In an amazing feat of design, the Enhanced Features Register (EFR) + * shares the address of the Interrupt Identification Register (IIR). + * Access to EFR is switched on by writing a magic value (0xbf) to the + * Line Control Register (LCR). Any interrupt firing during this time will + * see the EFR where it expects the IIR to be, leading to + * "Unexpected interrupt" messages. + * + * Prevent this possibility by claiming a mutex while accessing the EFR, + * and claiming the same mutex from within the interrupt handler. This is + * similar to disabling the interrupt, but that doesn't work because the + * bulk of the interrupt processing is run as a workqueue job in thread + * context. + */ +static void sc16is7xx_efr_lock(struct uart_port *port) +{ + struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); + + mutex_lock(&one->efr_lock); + + /* Backup content of LCR. */ + one->old_lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG); + + /* Enable access to Enhanced register set */ + sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_CONF_MODE_B); + + /* Disable cache updates when writing to EFR registers */ + regcache_cache_bypass(one->regmap, true); +} + +static void sc16is7xx_efr_unlock(struct uart_port *port) +{ + struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); + + /* Re-enable cache updates when writing to normal registers */ + regcache_cache_bypass(one->regmap, false); + + /* Restore original content of LCR */ + sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, one->old_lcr); + + mutex_unlock(&one->efr_lock); +} + static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit) { struct sc16is7xx_port *s = dev_get_drvdata(port->dev); @@ -538,39 +582,12 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud) div /= prescaler; }

- /* In an amazing feat of design, the Enhanced Features Register shares - * the address of the Interrupt Identification Register, and is - * switched in by writing a magic value (0xbf) to the Line Control - * Register. Any interrupt firing during this time will see the EFR - * where it expects the IIR to be, leading to "Unexpected interrupt" - * messages. - * - * Prevent this possibility by claiming a mutex while accessing the - * EFR, and claiming the same mutex from within the interrupt handler. - * This is similar to disabling the interrupt, but that doesn't work - * because the bulk of the interrupt processing is run as a workqueue - * job in thread context. - */ - mutex_lock(&one->efr_lock); - - lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG); - - /* Open the LCR divisors for configuration */ - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, - SC16IS7XX_LCR_CONF_MODE_B); - /* Enable enhanced features */ - regcache_cache_bypass(one->regmap, true); + sc16is7xx_efr_lock(port); sc16is7xx_port_update(port, SC16IS7XX_EFR_REG, SC16IS7XX_EFR_ENABLE_BIT, SC16IS7XX_EFR_ENABLE_BIT); - - regcache_cache_bypass(one->regmap, false); - - /* Put LCR back to the normal mode */ - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr); - - mutex_unlock(&one->efr_lock); + sc16is7xx_efr_unlock(port);

/* If bit MCR_CLKSEL is set, the divide by 4 prescaler is activated. */ sc16is7xx_port_update(port, SC16IS7XX_MCR_REG, @@ -580,7 +597,8 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)

mutex_lock(&one->efr_lock);

- /* Open the LCR divisors for configuration */ + /* Backup LCR and access special register set (DLL/DLH) */ + lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG); sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_CONF_MODE_A);

@@ -590,7 +608,7 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud) sc16is7xx_port_write(port, SC16IS7XX_DLL_REG, div % 256); regcache_cache_bypass(one->regmap, false);

- /* Put LCR back to the normal mode */ + /* Restore LCR and access to general register set */ sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);

mutex_unlock(&one->efr_lock); @@ -1073,17 +1091,7 @@ static void sc16is7xx_set_termios(struct uart_port *port, if (!(termios->c_cflag & CREAD)) port->ignore_status_mask |= SC16IS7XX_LSR_BRK_ERROR_MASK;

- /* As above, claim the mutex while accessing the EFR. */ - mutex_lock(&one->efr_lock); - - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, - SC16IS7XX_LCR_CONF_MODE_B); - /* Configure flow control */ - regcache_cache_bypass(one->regmap, true); - sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]); - sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]); - port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS); if (termios->c_cflag & CRTSCTS) { flow |= SC16IS7XX_EFR_AUTOCTS_BIT | @@ -1095,16 +1103,16 @@ static void sc16is7xx_set_termios(struct uart_port *port, if (termios->c_iflag & IXOFF) flow |= SC16IS7XX_EFR_SWFLOW1_BIT;

- sc16is7xx_port_update(port, - SC16IS7XX_EFR_REG, - SC16IS7XX_EFR_FLOWCTRL_BITS, - flow); - regcache_cache_bypass(one->regmap, false); - /* Update LCR register */ sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);

- mutex_unlock(&one->efr_lock); + /* Update EFR registers */ + sc16is7xx_efr_lock(port); + sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]); + sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]); + sc16is7xx_port_update(port, SC16IS7XX_EFR_REG, + SC16IS7XX_EFR_FLOWCTRL_BITS, flow); + sc16is7xx_efr_unlock(port);

/* Get baud rate generator configuration */ baud = uart_get_baud_rate(port, termios, old,

-- 2.51.0

Sasha Levin

6:53 p.m.

New subject: [PATCH 6.1.y 4/4] serial: sc16is7xx: remove useless enable of enhanced features

From: Hugo Villeneuve hvilleneuve@dimonoff.com

[ Upstream commit 1c05bf6c0262f946571a37678250193e46b1ff0f ]

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.

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index c0c2c1450e88d..458bf16543724 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -582,13 +582,6 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud) div /= prescaler; }

-- 2.51.0

days inactive

days old

linux-stable-mirror@lists.linaro.org

4 comments

participants

tags (0)

participants (2)

gregkh＠linuxfoundation.org
Sasha Levin