[PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Saravana Kannan]

These patches are on top of driver-core-next.

Even if stdout-path isn't set in DT, this patch should take console
probe times back to how they were before the deferred_probe_timeout
clean up series[1].

v1->v2:
- Fixed the accidental change that Tobias pointed out.
- Added Tested-by tag

[1] - https://lore.kernel.org/lkml/20220601070707.3946847-1-saravanak@google.com/

-Saravana

cc: Rob Herring <robh@kernel.org>
cc: sascha hauer <sha@pengutronix.de>
cc: peng fan <peng.fan@nxp.com>
cc: kevin hilman <khilman@kernel.org>
cc: ulf hansson <ulf.hansson@linaro.org>
cc: len brown <len.brown@intel.com>
cc: pavel machek <pavel@ucw.cz>
cc: joerg roedel <joro@8bytes.org>
cc: will deacon <will@kernel.org>
cc: andrew lunn <andrew@lunn.ch>
cc: heiner kallweit <hkallweit1@gmail.com>
cc: russell king <linux@armlinux.org.uk>
cc: "david s. miller" <davem@davemloft.net>
cc: eric dumazet <edumazet@google.com>
cc: jakub kicinski <kuba@kernel.org>
cc: paolo abeni <pabeni@redhat.com>
cc: linus walleij <linus.walleij@linaro.org>
cc: hideaki yoshifuji <yoshfuji@linux-ipv6.org>
cc: david ahern <dsahern@kernel.org>
cc: kernel-team@android.com
cc: linux-kernel@vger.kernel.org
cc: linux-pm@vger.kernel.org
cc: iommu@lists.linux-foundation.org
cc: netdev@vger.kernel.org
cc: linux-gpio@vger.kernel.org
Cc: kernel@pengutronix.de

Saravana Kannan (2):
  driver core: Add probe_no_timeout flag for drivers
  serial: Set probe_no_timeout for all DT based drivers

 drivers/base/base.h                         |  1 +
 drivers/base/core.c                         |  7 +++++++
 drivers/base/dd.c                           |  3 +++
 drivers/tty/ehv_bytechan.c                  |  1 +
 drivers/tty/goldfish.c                      |  1 +
 drivers/tty/hvc/hvc_opal.c                  |  1 +
 drivers/tty/serial/8250/8250_aspeed_vuart.c |  1 +
 drivers/tty/serial/8250/8250_bcm2835aux.c   |  1 +
 drivers/tty/serial/8250/8250_bcm7271.c      |  1 +
 drivers/tty/serial/8250/8250_dw.c           |  1 +
 drivers/tty/serial/8250/8250_em.c           |  1 +
 drivers/tty/serial/8250/8250_ingenic.c      |  1 +
 drivers/tty/serial/8250/8250_lpc18xx.c      |  1 +
 drivers/tty/serial/8250/8250_mtk.c          |  1 +
 drivers/tty/serial/8250/8250_of.c           |  1 +
 drivers/tty/serial/8250/8250_omap.c         |  1 +
 drivers/tty/serial/8250/8250_pxa.c          |  1 +
 drivers/tty/serial/8250/8250_tegra.c        |  1 +
 drivers/tty/serial/8250/8250_uniphier.c     |  1 +
 drivers/tty/serial/altera_jtaguart.c        |  1 +
 drivers/tty/serial/altera_uart.c            |  1 +
 drivers/tty/serial/amba-pl011.c             |  1 +
 drivers/tty/serial/apbuart.c                |  1 +
 drivers/tty/serial/ar933x_uart.c            |  1 +
 drivers/tty/serial/arc_uart.c               |  1 +
 drivers/tty/serial/atmel_serial.c           |  1 +
 drivers/tty/serial/bcm63xx_uart.c           |  1 +
 drivers/tty/serial/clps711x.c               |  1 +
 drivers/tty/serial/cpm_uart/cpm_uart_core.c |  1 +
 drivers/tty/serial/digicolor-usart.c        |  1 +
 drivers/tty/serial/fsl_linflexuart.c        |  1 +
 drivers/tty/serial/fsl_lpuart.c             |  1 +
 drivers/tty/serial/imx.c                    |  1 +
 drivers/tty/serial/lantiq.c                 |  1 +
 drivers/tty/serial/liteuart.c               |  1 +
 drivers/tty/serial/lpc32xx_hs.c             |  1 +
 drivers/tty/serial/max310x.c                |  1 +
 drivers/tty/serial/meson_uart.c             |  1 +
 drivers/tty/serial/milbeaut_usio.c          |  1 +
 drivers/tty/serial/mpc52xx_uart.c           |  1 +
 drivers/tty/serial/mps2-uart.c              |  1 +
 drivers/tty/serial/msm_serial.c             |  1 +
 drivers/tty/serial/mvebu-uart.c             |  1 +
 drivers/tty/serial/mxs-auart.c              |  1 +
 drivers/tty/serial/omap-serial.c            |  1 +
 drivers/tty/serial/owl-uart.c               |  1 +
 drivers/tty/serial/pic32_uart.c             |  1 +
 drivers/tty/serial/pmac_zilog.c             |  1 +
 drivers/tty/serial/pxa.c                    |  1 +
 drivers/tty/serial/qcom_geni_serial.c       |  1 +
 drivers/tty/serial/rda-uart.c               |  1 +
 drivers/tty/serial/samsung_tty.c            |  1 +
 drivers/tty/serial/sc16is7xx.c              |  1 +
 drivers/tty/serial/serial-tegra.c           |  1 +
 drivers/tty/serial/sh-sci.c                 |  1 +
 drivers/tty/serial/sifive.c                 |  1 +
 drivers/tty/serial/sprd_serial.c            |  1 +
 drivers/tty/serial/st-asc.c                 |  1 +
 drivers/tty/serial/stm32-usart.c            |  1 +
 drivers/tty/serial/sunhv.c                  |  1 +
 drivers/tty/serial/sunplus-uart.c           |  1 +
 drivers/tty/serial/sunsab.c                 |  1 +
 drivers/tty/serial/sunsu.c                  |  1 +
 drivers/tty/serial/sunzilog.c               |  1 +
 drivers/tty/serial/tegra-tcu.c              |  1 +
 drivers/tty/serial/uartlite.c               |  1 +
 drivers/tty/serial/ucc_uart.c               |  1 +
 drivers/tty/serial/vt8500_serial.c          |  1 +
 drivers/tty/serial/xilinx_uartps.c          |  1 +
 include/linux/device.h                      |  7 +++++++
 include/linux/device/driver.h               | 11 +++++++++++
 71 files changed, 95 insertions(+)

-- 
2.37.0.rc0.161.g10f37bed90-goog

[PATCH v2 1/2] driver core: Add probe_no_timeout flag for drivers

[Saravana Kannan]

This flag only needs to be set for drivers of devices that meet all the
following conditions:
- Need to probe successfully before userspace init in started
- Have optional suppliers
- Can't wait for deferred_probe_timeout to expire

fw_devlink=on uses this info, as needed, to ignore dependencies on supplier
devices that have not been added or supplier devices that don't have any
drivers.  It's still up to the driver to decide which of the missing
suppliers are optional or not.

Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
Reported-by: Sascha Hauer <sha@pengutronix.de>
Reported-by: Peng Fan <peng.fan@nxp.com>
Reported-by: Fabio Estevam <festevam@gmail.com>
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Tested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/base.h           |  1 +
 drivers/base/core.c           |  7 +++++++
 drivers/base/dd.c             |  3 +++
 include/linux/device.h        |  7 +++++++
 include/linux/device/driver.h | 11 +++++++++++
 5 files changed, 29 insertions(+)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index b3a43a164dcd..149822d2086f 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -193,6 +193,7 @@ extern void device_links_no_driver(struct device *dev);
 extern bool device_links_busy(struct device *dev);
 extern void device_links_unbind_consumers(struct device *dev);
 extern void fw_devlink_drivers_done(void);
+extern void fw_devlink_probe_no_timeout(void);
 
 /* device pm support */
 void device_pm_move_to_tail(struct device *dev);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ccdd5b4295de..8e18904a1584 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -54,6 +54,7 @@ static unsigned int defer_sync_state_count = 1;
 static DEFINE_MUTEX(fwnode_link_lock);
 static bool fw_devlink_is_permissive(void);
 static bool fw_devlink_drv_reg_done;
+static bool fw_devlink_no_timeout;
 static bool fw_devlink_best_effort;
 
 /**
@@ -969,6 +970,7 @@ static void device_links_missing_supplier(struct device *dev)
 static bool dev_is_best_effort(struct device *dev)
 {
 	return (fw_devlink_best_effort && dev->can_match) ||
+		(fw_devlink_no_timeout && dev->probe_no_timeout) ||
 		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
 }
 
@@ -1688,6 +1690,11 @@ void fw_devlink_drivers_done(void)
 	device_links_write_unlock();
 }
 
+void fw_devlink_probe_no_timeout(void)
+{
+	fw_devlink_no_timeout = true;
+}
+
 /**
  * wait_for_init_devices_probe - Try to probe any device needed for init
  *
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 70f79fc71539..943b0363aaab 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -324,6 +324,8 @@ static int deferred_probe_initcall(void)
 
 	if (!IS_ENABLED(CONFIG_MODULES))
 		fw_devlink_drivers_done();
+	else
+		fw_devlink_probe_no_timeout();
 
 	/*
 	 * Trigger deferred probe again, this time we won't defer anything
@@ -734,6 +736,7 @@ static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 		return -EBUSY;
 
 	dev->can_match = true;
+	dev->probe_no_timeout = drv->probe_no_timeout;
 	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 		 drv->bus->name, __func__, dev_name(dev), drv->name);
 
diff --git a/include/linux/device.h b/include/linux/device.h
index 424b55df0272..e6246b6cf6cf 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -536,6 +536,12 @@ struct device_physical_location {
  * @can_match:	The device has matched with a driver at least once or it is in
  *		a bus (like AMBA) which can't check for matching drivers until
  *		other devices probe successfully.
+ * @probe_no_timeout: Set by driver core to indicate that this device's probe
+ *		can't wait till driver_probe_timeout expires. This information
+ *		is used by fw_devlink=on to avoid deferring the probe of this
+ *		device to wait on supplier devices that haven't been added or
+ *		probed successfully.
+ *		See also: probe_no_timeout in struct driver.
  * @dma_coherent: this particular device is dma coherent, even if the
  *		architecture supports non-coherent devices.
  * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
@@ -642,6 +648,7 @@ struct device {
 	bool			of_node_reused:1;
 	bool			state_synced:1;
 	bool			can_match:1;
+	bool			probe_no_timeout:1;
 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h
index 7acaabde5396..2ce60e511504 100644
--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h
@@ -55,6 +55,15 @@ enum probe_type {
  * @owner:	The module owner.
  * @mod_name:	Used for built-in modules.
  * @suppress_bind_attrs: Disables bind/unbind via sysfs.
+ * @probe_no_timeout: Set to true by drivers that bind to devices that meet all
+ *		these conditions:
+ *		- Need to probe successfully before userspace init in started
+ *		- Have optional suppliers
+ *		- Can't wait for deferred_probe_timeout to expire
+ *		fw_devlink=on uses this info, as needed, to ignore dependencies
+ *		on supplier devices that have not been added or supplier devices
+ *		that don't have any drivers. It's still up to the driver to
+ *		decide which of the missing suppliers are optional or not.
  * @probe_type:	Type of the probe (synchronous or asynchronous) to use.
  * @of_match_table: The open firmware table.
  * @acpi_match_table: The ACPI match table.
@@ -101,6 +110,8 @@ struct device_driver {
 	const char		*mod_name;	/* used for built-in modules */
 
 	bool suppress_bind_attrs;	/* disables bind/unbind via sysfs */
+	bool probe_no_timeout;
+
 	enum probe_type probe_type;
 
 	const struct of_device_id	*of_match_table;
-- 
2.37.0.rc0.161.g10f37bed90-goog

[PATCH v2 2/2] serial: Set probe_no_timeout for all DT based drivers

[Saravana Kannan]

With commit 71066545b48e ("driver core: Set fw_devlink.strict=1 by
default") the probing of TTY consoles could get delayed if they have
optional suppliers that are listed in DT, but those suppliers don't
probe by the time kernel boot finishes. The console devices will probe
eventually after driver_probe_timeout expires.

However, since consoles are often used for debugging kernel issues, it
does not make sense to delay their probe. So, set the newly added
probe_no_timeout flag for all serial drivers that at DT based. This way,
fw_devlink will know not to delay the probing of the consoles past
kernel boot.

Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
Reported-by: Sascha Hauer <sha@pengutronix.de>
Reported-by: Peng Fan <peng.fan@nxp.com>
Reported-by: Fabio Estevam <festevam@gmail.com>
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Tested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/tty/ehv_bytechan.c                  | 1 +
 drivers/tty/goldfish.c                      | 1 +
 drivers/tty/hvc/hvc_opal.c                  | 1 +
 drivers/tty/serial/8250/8250_aspeed_vuart.c | 1 +
 drivers/tty/serial/8250/8250_bcm2835aux.c   | 1 +
 drivers/tty/serial/8250/8250_bcm7271.c      | 1 +
 drivers/tty/serial/8250/8250_dw.c           | 1 +
 drivers/tty/serial/8250/8250_em.c           | 1 +
 drivers/tty/serial/8250/8250_ingenic.c      | 1 +
 drivers/tty/serial/8250/8250_lpc18xx.c      | 1 +
 drivers/tty/serial/8250/8250_mtk.c          | 1 +
 drivers/tty/serial/8250/8250_of.c           | 1 +
 drivers/tty/serial/8250/8250_omap.c         | 1 +
 drivers/tty/serial/8250/8250_pxa.c          | 1 +
 drivers/tty/serial/8250/8250_tegra.c        | 1 +
 drivers/tty/serial/8250/8250_uniphier.c     | 1 +
 drivers/tty/serial/altera_jtaguart.c        | 1 +
 drivers/tty/serial/altera_uart.c            | 1 +
 drivers/tty/serial/amba-pl011.c             | 1 +
 drivers/tty/serial/apbuart.c                | 1 +
 drivers/tty/serial/ar933x_uart.c            | 1 +
 drivers/tty/serial/arc_uart.c               | 1 +
 drivers/tty/serial/atmel_serial.c           | 1 +
 drivers/tty/serial/bcm63xx_uart.c           | 1 +
 drivers/tty/serial/clps711x.c               | 1 +
 drivers/tty/serial/cpm_uart/cpm_uart_core.c | 1 +
 drivers/tty/serial/digicolor-usart.c        | 1 +
 drivers/tty/serial/fsl_linflexuart.c        | 1 +
 drivers/tty/serial/fsl_lpuart.c             | 1 +
 drivers/tty/serial/imx.c                    | 1 +
 drivers/tty/serial/lantiq.c                 | 1 +
 drivers/tty/serial/liteuart.c               | 1 +
 drivers/tty/serial/lpc32xx_hs.c             | 1 +
 drivers/tty/serial/max310x.c                | 1 +
 drivers/tty/serial/meson_uart.c             | 1 +
 drivers/tty/serial/milbeaut_usio.c          | 1 +
 drivers/tty/serial/mpc52xx_uart.c           | 1 +
 drivers/tty/serial/mps2-uart.c              | 1 +
 drivers/tty/serial/msm_serial.c             | 1 +
 drivers/tty/serial/mvebu-uart.c             | 1 +
 drivers/tty/serial/mxs-auart.c              | 1 +
 drivers/tty/serial/omap-serial.c            | 1 +
 drivers/tty/serial/owl-uart.c               | 1 +
 drivers/tty/serial/pic32_uart.c             | 1 +
 drivers/tty/serial/pmac_zilog.c             | 1 +
 drivers/tty/serial/pxa.c                    | 1 +
 drivers/tty/serial/qcom_geni_serial.c       | 1 +
 drivers/tty/serial/rda-uart.c               | 1 +
 drivers/tty/serial/samsung_tty.c            | 1 +
 drivers/tty/serial/sc16is7xx.c              | 1 +
 drivers/tty/serial/serial-tegra.c           | 1 +
 drivers/tty/serial/sh-sci.c                 | 1 +
 drivers/tty/serial/sifive.c                 | 1 +
 drivers/tty/serial/sprd_serial.c            | 1 +
 drivers/tty/serial/st-asc.c                 | 1 +
 drivers/tty/serial/stm32-usart.c            | 1 +
 drivers/tty/serial/sunhv.c                  | 1 +
 drivers/tty/serial/sunplus-uart.c           | 1 +
 drivers/tty/serial/sunsab.c                 | 1 +
 drivers/tty/serial/sunsu.c                  | 1 +
 drivers/tty/serial/sunzilog.c               | 1 +
 drivers/tty/serial/tegra-tcu.c              | 1 +
 drivers/tty/serial/uartlite.c               | 1 +
 drivers/tty/serial/ucc_uart.c               | 1 +
 drivers/tty/serial/vt8500_serial.c          | 1 +
 drivers/tty/serial/xilinx_uartps.c          | 1 +
 66 files changed, 66 insertions(+)

diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c
index 19d32cb6af84..6de710da99be 100644
--- a/drivers/tty/ehv_bytechan.c
+++ b/drivers/tty/ehv_bytechan.c
@@ -739,6 +739,7 @@ static struct platform_driver ehv_bc_tty_driver = {
 	.driver = {
 		.name = "ehv-bc",
 		.of_match_table = ehv_bc_tty_of_ids,
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = true,
 	},
 	.probe		= ehv_bc_tty_probe,
diff --git a/drivers/tty/goldfish.c b/drivers/tty/goldfish.c
index c7968aecd870..f9760598c836 100644
--- a/drivers/tty/goldfish.c
+++ b/drivers/tty/goldfish.c
@@ -474,6 +474,7 @@ static struct platform_driver goldfish_tty_platform_driver = {
 	.driver = {
 		.name = "goldfish_tty",
 		.of_match_table = goldfish_tty_of_match,
+		.probe_no_timeout = true,
 	}
 };
 
diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index 794c7b18aa06..08202c2f8ead 100644
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -253,6 +253,7 @@ static struct platform_driver hvc_opal_driver = {
 	.driver		= {
 		.name	= hvc_opal_name,
 		.of_match_table	= hvc_opal_match,
+		.probe_no_timeout = true,
 	}
 };
 
diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
index 9d2a7856784f..ca4b89ae13a4 100644
--- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
+++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
@@ -592,6 +592,7 @@ static struct platform_driver aspeed_vuart_driver = {
 	.driver = {
 		.name = "aspeed-vuart",
 		.of_match_table = aspeed_vuart_table,
+		.probe_no_timeout = true,
 	},
 	.probe = aspeed_vuart_probe,
 	.remove = aspeed_vuart_remove,
diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c
index 2a1226a78a0c..6c00ba7a123a 100644
--- a/drivers/tty/serial/8250/8250_bcm2835aux.c
+++ b/drivers/tty/serial/8250/8250_bcm2835aux.c
@@ -223,6 +223,7 @@ static struct platform_driver bcm2835aux_serial_driver = {
 		.name = "bcm2835-aux-uart",
 		.of_match_table = bcm2835aux_serial_match,
 		.acpi_match_table = bcm2835aux_serial_acpi_match,
+		.probe_no_timeout = true,
 	},
 	.probe  = bcm2835aux_serial_probe,
 	.remove = bcm2835aux_serial_remove,
diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index 9b878d023dac..7898dcbff07e 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -1193,6 +1193,7 @@ static struct platform_driver brcmuart_platform_driver = {
 		.name	= "bcm7271-uart",
 		.pm		= &brcmuart_dev_pm_ops,
 		.of_match_table = brcmuart_dt_ids,
+		.probe_no_timeout = true,
 	},
 	.probe		= brcmuart_probe,
 	.remove		= brcmuart_remove,
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index f57bbd32ef11..616f5197378a 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -795,6 +795,7 @@ static struct platform_driver dw8250_platform_driver = {
 		.pm		= &dw8250_pm_ops,
 		.of_match_table	= dw8250_of_match,
 		.acpi_match_table = dw8250_acpi_match,
+		.probe_no_timeout = true,
 	},
 	.probe			= dw8250_probe,
 	.remove			= dw8250_remove,
diff --git a/drivers/tty/serial/8250/8250_em.c b/drivers/tty/serial/8250/8250_em.c
index f8e99995eee9..0dc9a2e45cf2 100644
--- a/drivers/tty/serial/8250/8250_em.c
+++ b/drivers/tty/serial/8250/8250_em.c
@@ -151,6 +151,7 @@ static struct platform_driver serial8250_em_platform_driver = {
 	.driver = {
 		.name		= "serial8250-em",
 		.of_match_table = serial8250_em_dt_ids,
+		.probe_no_timeout = true,
 	},
 	.probe			= serial8250_em_probe,
 	.remove			= serial8250_em_remove,
diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c
index cff91aa03f29..dc595a4a49a0 100644
--- a/drivers/tty/serial/8250/8250_ingenic.c
+++ b/drivers/tty/serial/8250/8250_ingenic.c
@@ -341,6 +341,7 @@ static struct platform_driver ingenic_uart_platform_driver = {
 	.driver = {
 		.name		= "ingenic-uart",
 		.of_match_table	= of_match,
+		.probe_no_timeout = true,
 	},
 	.probe			= ingenic_uart_probe,
 	.remove			= ingenic_uart_remove,
diff --git a/drivers/tty/serial/8250/8250_lpc18xx.c b/drivers/tty/serial/8250/8250_lpc18xx.c
index 570e25d6f37e..d9c91c57331c 100644
--- a/drivers/tty/serial/8250/8250_lpc18xx.c
+++ b/drivers/tty/serial/8250/8250_lpc18xx.c
@@ -215,6 +215,7 @@ static struct platform_driver lpc18xx_serial_driver = {
 	.driver = {
 		.name = "lpc18xx-uart",
 		.of_match_table = lpc18xx_serial_match,
+		.probe_no_timeout = true,
 	},
 };
 module_platform_driver(lpc18xx_serial_driver);
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index 54051ec7b499..85e8a19c0929 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -671,6 +671,7 @@ static struct platform_driver mtk8250_platform_driver = {
 		.name		= "mt6577-uart",
 		.pm		= &mtk8250_pm_ops,
 		.of_match_table	= mtk8250_of_match,
+		.probe_no_timeout = true,
 	},
 	.probe			= mtk8250_probe,
 	.remove			= mtk8250_remove,
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 5a699a1aa79c..580abd22d3c6 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -343,6 +343,7 @@ static struct platform_driver of_platform_serial_driver = {
 	.driver = {
 		.name = "of_serial",
 		.of_match_table = of_platform_serial_table,
+		.probe_no_timeout = true,
 		.pm = &of_serial_pm_ops,
 	},
 	.probe = of_platform_serial_probe,
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index ac8bfa042391..8d83597174b4 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1694,6 +1694,7 @@ static struct platform_driver omap8250_platform_driver = {
 		.name		= "omap8250",
 		.pm		= &omap8250_dev_pm_ops,
 		.of_match_table = omap8250_dt_ids,
+		.probe_no_timeout = true,
 	},
 	.probe			= omap8250_probe,
 	.remove			= omap8250_remove,
diff --git a/drivers/tty/serial/8250/8250_pxa.c b/drivers/tty/serial/8250/8250_pxa.c
index 795e55142d4c..9f7bb52fabbe 100644
--- a/drivers/tty/serial/8250/8250_pxa.c
+++ b/drivers/tty/serial/8250/8250_pxa.c
@@ -165,6 +165,7 @@ static struct platform_driver serial_pxa_driver = {
 		.name	= "pxa2xx-uart",
 		.pm	= &serial_pxa_pm_ops,
 		.of_match_table = serial_pxa_dt_ids,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/8250/8250_tegra.c b/drivers/tty/serial/8250/8250_tegra.c
index e7cddeec9d8e..45630f7d9e98 100644
--- a/drivers/tty/serial/8250/8250_tegra.c
+++ b/drivers/tty/serial/8250/8250_tegra.c
@@ -187,6 +187,7 @@ static struct platform_driver tegra_uart_driver = {
 		.pm = &tegra_uart_pm_ops,
 		.of_match_table = tegra_uart_of_match,
 		.acpi_match_table = ACPI_PTR(tegra_uart_acpi_match),
+		.probe_no_timeout = true,
 	},
 	.probe = tegra_uart_probe,
 	.remove = tegra_uart_remove,
diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index a2978abab0db..7fdf45c4513d 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -297,6 +297,7 @@ static struct platform_driver uniphier_uart_platform_driver = {
 	.driver = {
 		.name	= "uniphier-uart",
 		.of_match_table = uniphier_uart_match,
+		.probe_no_timeout = true,
 		.pm = &uniphier_uart_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/altera_jtaguart.c b/drivers/tty/serial/altera_jtaguart.c
index cb791c5149a3..548934284691 100644
--- a/drivers/tty/serial/altera_jtaguart.c
+++ b/drivers/tty/serial/altera_jtaguart.c
@@ -493,6 +493,7 @@ static struct platform_driver altera_jtaguart_platform_driver = {
 	.driver	= {
 		.name		= DRV_NAME,
 		.of_match_table	= of_match_ptr(altera_jtaguart_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/altera_uart.c b/drivers/tty/serial/altera_uart.c
index 8b749ed557c6..25c834f900eb 100644
--- a/drivers/tty/serial/altera_uart.c
+++ b/drivers/tty/serial/altera_uart.c
@@ -645,6 +645,7 @@ static struct platform_driver altera_uart_platform_driver = {
 	.driver	= {
 		.name		= DRV_NAME,
 		.of_match_table	= of_match_ptr(altera_uart_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 97ef41cb2721..eae866568f14 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2912,6 +2912,7 @@ static struct platform_driver arm_sbsa_uart_platform_driver = {
 		.pm	= &pl011_dev_pm_ops,
 		.of_match_table = of_match_ptr(sbsa_uart_of_match),
 		.acpi_match_table = ACPI_PTR(sbsa_uart_acpi_match),
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011),
 	},
 };
diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c
index 9ef82d870ff2..72c1b7884a3b 100644
--- a/drivers/tty/serial/apbuart.c
+++ b/drivers/tty/serial/apbuart.c
@@ -583,6 +583,7 @@ static struct platform_driver grlib_apbuart_of_driver = {
 	.driver = {
 		.name = "grlib-apbuart",
 		.of_match_table = apbuart_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index 6269dbf93546..f0013be1a7c7 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -842,6 +842,7 @@ static struct platform_driver ar933x_uart_platform_driver = {
 	.driver		= {
 		.name		= DRIVER_NAME,
 		.of_match_table = of_match_ptr(ar933x_uart_of_ids),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 2a09e92ef9ed..7998c285fc6c 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -650,6 +650,7 @@ static struct platform_driver arc_platform_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table  = arc_uart_dt_ids,
+		.probe_no_timeout = true,
 	 },
 };
 
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index dd1c7e4bd1c9..ff74ea97b305 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -3020,6 +3020,7 @@ static struct platform_driver atmel_serial_driver = {
 	.driver		= {
 		.name			= "atmel_usart_serial",
 		.of_match_table		= of_match_ptr(atmel_serial_dt_ids),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/bcm63xx_uart.c b/drivers/tty/serial/bcm63xx_uart.c
index 53b43174aa40..d91c49c50ac6 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -890,6 +890,7 @@ static struct platform_driver bcm_uart_platform_driver = {
 	.driver	= {
 		.name  = "bcm63xx_uart",
 		.of_match_table = bcm63xx_of_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/clps711x.c b/drivers/tty/serial/clps711x.c
index b9b66ad31a08..b81710802937 100644
--- a/drivers/tty/serial/clps711x.c
+++ b/drivers/tty/serial/clps711x.c
@@ -528,6 +528,7 @@ static struct platform_driver clps711x_uart_platform = {
 	.driver = {
 		.name		= "clps711x-uart",
 		.of_match_table	= of_match_ptr(clps711x_uart_dt_ids),
+		.probe_no_timeout = true,
 	},
 	.probe	= uart_clps711x_probe,
 	.remove	= uart_clps711x_remove,
diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
index db07d6a5d764..ff269637bc28 100644
--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1470,6 +1470,7 @@ static struct platform_driver cpm_uart_driver = {
 	.driver = {
 		.name = "cpm_uart",
 		.of_match_table = cpm_uart_match,
+		.probe_no_timeout = true,
 	},
 	.probe = cpm_uart_probe,
 	.remove = cpm_uart_remove,
diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index af951e6a2ef4..b2148b48d195 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -524,6 +524,7 @@ static struct platform_driver digicolor_uart_platform = {
 	.driver = {
 		.name		= "digicolor-usart",
 		.of_match_table	= of_match_ptr(digicolor_uart_dt_ids),
+		.probe_no_timeout = true,
 	},
 	.probe	= digicolor_uart_probe,
 	.remove	= digicolor_uart_remove,
diff --git a/drivers/tty/serial/fsl_linflexuart.c b/drivers/tty/serial/fsl_linflexuart.c
index 98bb0c315e13..08514238af36 100644
--- a/drivers/tty/serial/fsl_linflexuart.c
+++ b/drivers/tty/serial/fsl_linflexuart.c
@@ -889,6 +889,7 @@ static struct platform_driver linflex_driver = {
 	.driver		= {
 		.name	= DRIVER_NAME,
 		.of_match_table	= linflex_dt_ids,
+		.probe_no_timeout = true,
 		.pm	= &linflex_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 0d6e62f6bb07..64e969278c72 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2857,6 +2857,7 @@ static struct platform_driver lpuart_driver = {
 	.driver		= {
 		.name	= "fsl-lpuart",
 		.of_match_table = lpuart_dt_ids,
+		.probe_no_timeout = true,
 		.pm	= &lpuart_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 30edb35a6a15..deb2539d0fbc 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2604,6 +2604,7 @@ static struct platform_driver imx_uart_platform_driver = {
 	.driver = {
 		.name = "imx-uart",
 		.of_match_table = imx_uart_dt_ids,
+		.probe_no_timeout = true,
 		.pm = &imx_uart_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
index a3120c3347dd..279ee1ba6ae1 100644
--- a/drivers/tty/serial/lantiq.c
+++ b/drivers/tty/serial/lantiq.c
@@ -942,6 +942,7 @@ static struct platform_driver lqasc_driver = {
 	.driver		= {
 		.name	= DRVNAME,
 		.of_match_table = ltq_asc_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
index 328b50521f14..e92cf2a1b4cc 100644
--- a/drivers/tty/serial/liteuart.c
+++ b/drivers/tty/serial/liteuart.c
@@ -324,6 +324,7 @@ static struct platform_driver liteuart_platform_driver = {
 	.driver = {
 		.name = "liteuart",
 		.of_match_table = liteuart_of_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index 93140cac1ca1..bb655bd7f678 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -727,6 +727,7 @@ static struct platform_driver serial_hs_lpc32xx_driver = {
 	.driver		= {
 		.name	= MODNAME,
 		.of_match_table	= serial_hs_lpc32xx_dt_ids,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index a0b6ea52d133..09e3cee4e0ce 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1504,6 +1504,7 @@ static struct spi_driver max310x_spi_driver = {
 	.driver = {
 		.name		= MAX310X_NAME,
 		.of_match_table	= max310x_dt_ids,
+		.probe_no_timeout = true,
 		.pm		= &max310x_pm_ops,
 	},
 	.probe		= max310x_spi_probe,
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 4869c0059c98..f0104d85484e 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -826,6 +826,7 @@ static  struct platform_driver meson_uart_platform_driver = {
 	.driver		= {
 		.name		= "meson_uart",
 		.of_match_table	= meson_uart_dt_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
index 347088bb380e..e175e6e0e7c7 100644
--- a/drivers/tty/serial/milbeaut_usio.c
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -576,6 +576,7 @@ static struct platform_driver mlb_usio_driver = {
 	.driver         = {
 		.name   = USIO_NAME,
 		.of_match_table = mlb_usio_dt_ids,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index e50f069b5ebb..da9c60baf0ed 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -1885,6 +1885,7 @@ static struct platform_driver mpc52xx_uart_of_driver = {
 	.driver = {
 		.name = "mpc52xx-psc-uart",
 		.of_match_table = mpc52xx_uart_of_match,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 5e9429dcc51f..4cb82ebe0ec7 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c
@@ -634,6 +634,7 @@ static struct platform_driver mps2_serial_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table = of_match_ptr(mps2_match),
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = true,
 	},
 };
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index e676ec761f18..989a5cc8612c 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -1890,6 +1890,7 @@ static struct platform_driver msm_platform_driver = {
 		.name = "msm_serial",
 		.pm = &msm_serial_dev_pm_ops,
 		.of_match_table = msm_match_table,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 0429c2a54290..b5b49773fcce 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -1049,6 +1049,7 @@ static struct platform_driver mvebu_uart_platform_driver = {
 	.driver	= {
 		.name  = "mvebu-uart",
 		.of_match_table = of_match_ptr(mvebu_uart_of_match),
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = true,
 #if defined(CONFIG_PM)
 		.pm	= &mvebu_uart_pm_ops,
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 1944daf8593a..8bd871b5f263 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1725,6 +1725,7 @@ static struct platform_driver mxs_auart_driver = {
 	.driver = {
 		.name = "mxs-auart",
 		.of_match_table = mxs_auart_dt_ids,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 46f4d4cacb6e..2e61d9cbbecb 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1834,6 +1834,7 @@ static struct platform_driver serial_omap_driver = {
 		.name	= OMAP_SERIAL_DRIVER_NAME,
 		.pm	= &serial_omap_dev_pm_ops,
 		.of_match_table = of_match_ptr(omap_serial_of_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
index 44d20e5a7dd3..858223abab9d 100644
--- a/drivers/tty/serial/owl-uart.c
+++ b/drivers/tty/serial/owl-uart.c
@@ -766,6 +766,7 @@ static struct platform_driver owl_uart_platform_driver = {
 	.driver = {
 		.name = "owl-uart",
 		.of_match_table = owl_uart_dt_matches,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
index b399aac530fe..3f08ac2f38b4 100644
--- a/drivers/tty/serial/pic32_uart.c
+++ b/drivers/tty/serial/pic32_uart.c
@@ -986,6 +986,7 @@ static struct platform_driver pic32_uart_platform_driver = {
 	.driver		= {
 		.name	= PIC32_DEV_NAME,
 		.of_match_table	= of_match_ptr(pic32_serial_dt_ids),
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_PIC32),
 	},
 };
diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
index 3133446e806c..552efe9eef7b 100644
--- a/drivers/tty/serial/pmac_zilog.c
+++ b/drivers/tty/serial/pmac_zilog.c
@@ -1790,6 +1790,7 @@ static struct macio_driver pmz_driver = {
 		.name 		= "pmac_zilog",
 		.owner		= THIS_MODULE,
 		.of_match_table	= pmz_match,
+		.probe_no_timeout = true,
 	},
 	.probe		= pmz_attach,
 	.remove		= pmz_detach,
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index e80ba8e10407..b0b91f69b24c 100644
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -910,6 +910,7 @@ static struct platform_driver serial_pxa_driver = {
 #endif
 		.suppress_bind_attrs = true,
 		.of_match_table = serial_pxa_dt_ids,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 4733a233bd0c..c47cfd4a5ea5 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1541,6 +1541,7 @@ static struct platform_driver qcom_geni_serial_platform_driver = {
 	.driver = {
 		.name = "qcom_geni_serial",
 		.of_match_table = qcom_geni_serial_match_table,
+		.probe_no_timeout = true,
 		.pm = &qcom_geni_serial_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c
index f556b4955f59..9e7927de0972 100644
--- a/drivers/tty/serial/rda-uart.c
+++ b/drivers/tty/serial/rda-uart.c
@@ -797,6 +797,7 @@ static struct platform_driver rda_uart_platform_driver = {
 	.driver = {
 		.name = "rda-uart",
 		.of_match_table = rda_uart_dt_matches,
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index d5ca904def34..e3d77bc2420f 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2939,6 +2939,7 @@ static struct platform_driver samsung_serial_driver = {
 		.name	= "samsung-uart",
 		.pm	= SERIAL_SAMSUNG_PM_OPS,
 		.of_match_table	= of_match_ptr(s3c24xx_uart_dt_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 8472bf70477c..dfc455850908 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1652,6 +1652,7 @@ static struct spi_driver sc16is7xx_spi_uart_driver = {
 	.driver = {
 		.name		= SC16IS7XX_NAME,
 		.of_match_table	= sc16is7xx_dt_ids,
+		.probe_no_timeout = true,
 	},
 	.probe		= sc16is7xx_spi_probe,
 	.remove		= sc16is7xx_spi_remove,
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index d942ab152f5a..240166a36569 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -1653,6 +1653,7 @@ static struct platform_driver tegra_uart_platform_driver = {
 	.driver		= {
 		.name	= "serial-tegra",
 		.of_match_table = tegra_uart_of_match,
+		.probe_no_timeout = true,
 		.pm	= &tegra_uart_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 0075a1420005..ee90562c7e8d 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -3396,6 +3396,7 @@ static struct platform_driver sci_driver = {
 		.name	= "sh-sci",
 		.pm	= &sci_dev_pm_ops,
 		.of_match_table = of_match_ptr(of_sci_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index c0869b080cc3..a9f3a4562205 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -1066,6 +1066,7 @@ static struct platform_driver sifive_serial_platform_driver = {
 	.driver		= {
 		.name	= SIFIVE_SERIAL_NAME,
 		.of_match_table = of_match_ptr(sifive_serial_of_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 4329b9c9cbf0..6c01e647bc4d 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -1278,6 +1278,7 @@ static struct platform_driver sprd_platform_driver = {
 	.driver		= {
 		.name	= "sprd_serial",
 		.of_match_table = of_match_ptr(serial_ids),
+		.probe_no_timeout = true,
 		.pm	= &sprd_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index 1b0da603ab54..a01c10522bb6 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -973,6 +973,7 @@ static struct platform_driver asc_serial_driver = {
 		.name	= DRIVER_NAME,
 		.pm	= &asc_serial_pm_ops,
 		.of_match_table = of_match_ptr(asc_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index b7b44f4050d4..5aa01cd6f24f 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -2019,6 +2019,7 @@ static struct platform_driver stm32_serial_driver = {
 		.name	= DRIVER_NAME,
 		.pm	= &stm32_serial_pm_ops,
 		.of_match_table = of_match_ptr(stm32_match),
+		.probe_no_timeout = true,
 	},
 };
 
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index eafada8fb6fa..05bf49af8328 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -630,6 +630,7 @@ static struct platform_driver hv_driver = {
 	.driver = {
 		.name = "hv",
 		.of_match_table = hv_match,
+		.probe_no_timeout = true,
 	},
 	.probe		= hv_probe,
 	.remove		= hv_remove,
diff --git a/drivers/tty/serial/sunplus-uart.c b/drivers/tty/serial/sunplus-uart.c
index 60c73662f955..b5b09aedab9c 100644
--- a/drivers/tty/serial/sunplus-uart.c
+++ b/drivers/tty/serial/sunplus-uart.c
@@ -709,6 +709,7 @@ static struct platform_driver sunplus_uart_platform_driver = {
 	.driver = {
 		.name	= "sunplus_uart",
 		.of_match_table = sp_uart_of_match,
+		.probe_no_timeout = true,
 		.pm     = &sunplus_uart_pm_ops,
 	}
 };
diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
index 6ea52293d9f3..3d2eea131a67 100644
--- a/drivers/tty/serial/sunsab.c
+++ b/drivers/tty/serial/sunsab.c
@@ -1103,6 +1103,7 @@ static struct platform_driver sab_driver = {
 	.driver = {
 		.name = "sab",
 		.of_match_table = sab_match,
+		.probe_no_timeout = true,
 	},
 	.probe		= sab_probe,
 	.remove		= sab_remove,
diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c
index fff50b5b82eb..598691174e08 100644
--- a/drivers/tty/serial/sunsu.c
+++ b/drivers/tty/serial/sunsu.c
@@ -1566,6 +1566,7 @@ static struct platform_driver su_driver = {
 	.driver = {
 		.name = "su",
 		.of_match_table = su_match,
+		.probe_no_timeout = true,
 	},
 	.probe		= su_probe,
 	.remove		= su_remove,
diff --git a/drivers/tty/serial/sunzilog.c b/drivers/tty/serial/sunzilog.c
index c14275d83b0b..15dc30f493d9 100644
--- a/drivers/tty/serial/sunzilog.c
+++ b/drivers/tty/serial/sunzilog.c
@@ -1541,6 +1541,7 @@ static struct platform_driver zs_driver = {
 	.driver = {
 		.name = "zs",
 		.of_match_table = zs_match,
+		.probe_no_timeout = true,
 	},
 	.probe		= zs_probe,
 	.remove		= zs_remove,
diff --git a/drivers/tty/serial/tegra-tcu.c b/drivers/tty/serial/tegra-tcu.c
index 4877c54c613d..aa0ba869e590 100644
--- a/drivers/tty/serial/tegra-tcu.c
+++ b/drivers/tty/serial/tegra-tcu.c
@@ -292,6 +292,7 @@ static struct platform_driver tegra_tcu_driver = {
 	.driver = {
 		.name = "tegra-tcu",
 		.of_match_table = tegra_tcu_match,
+		.probe_no_timeout = true,
 	},
 	.probe = tegra_tcu_probe,
 	.remove = tegra_tcu_remove,
diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index 880e2afbb97b..a7f600e57a25 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c
@@ -919,6 +919,7 @@ static struct platform_driver ulite_platform_driver = {
 	.driver = {
 		.name  = "uartlite",
 		.of_match_table = of_match_ptr(ulite_of_match),
+		.probe_no_timeout = true,
 		.pm = &ulite_pm_ops,
 	},
 };
diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
index 6000853973c1..a2e637876db0 100644
--- a/drivers/tty/serial/ucc_uart.c
+++ b/drivers/tty/serial/ucc_uart.c
@@ -1500,6 +1500,7 @@ static struct platform_driver ucc_uart_of_driver = {
 	.driver = {
 		.name = "ucc_uart",
 		.of_match_table    = ucc_uart_match,
+		.probe_no_timeout = true,
 	},
 	.probe  	= ucc_uart_probe,
 	.remove 	= ucc_uart_remove,
diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 6f08136ce78a..074b4e8b61b6 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -722,6 +722,7 @@ static struct platform_driver vt8500_platform_driver = {
 	.driver = {
 		.name = "vt8500_serial",
 		.of_match_table = wmt_dt_ids,
+		.probe_no_timeout = true,
 		.suppress_bind_attrs = true,
 	},
 };
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 9e01fe6c0ab8..7e941c7e819e 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1656,6 +1656,7 @@ static struct platform_driver cdns_uart_platform_driver = {
 	.driver  = {
 		.name = CDNS_UART_NAME,
 		.of_match_table = cdns_uart_of_match,
+		.probe_no_timeout = true,
 		.pm = &cdns_uart_dev_pm_ops,
 		.suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_XILINX_PS_UART),
 		},
-- 
2.37.0.rc0.161.g10f37bed90-goog

Re: [PATCH v2 2/2] serial: Set probe_no_timeout for all DT based drivers

[Andy Shevchenko]

On Fri, Jul 1, 2022 at 3:28 AM Saravana Kannan <saravanak@google.com> wrote:
>
> With commit 71066545b48e ("driver core: Set fw_devlink.strict=1 by
> default") the probing of TTY consoles could get delayed if they have
> optional suppliers that are listed in DT, but those suppliers don't
> probe by the time kernel boot finishes. The console devices will probe
> eventually after driver_probe_timeout expires.
>
> However, since consoles are often used for debugging kernel issues, it
> does not make sense to delay their probe. So, set the newly added
> probe_no_timeout flag for all serial drivers that at DT based. This way,
> fw_devlink will know not to delay the probing of the consoles past
> kernel boot.

Same question, do you think only serial drivers need that?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Greg Kroah-Hartman]

On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> These patches are on top of driver-core-next.
> 
> Even if stdout-path isn't set in DT, this patch should take console
> probe times back to how they were before the deferred_probe_timeout
> clean up series[1].

Now dropped from my queue due to lack of a response to other reviewer's
questions.

thanks,

greg k-h

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Saravana Kannan]

On Tue, Aug 23, 2022 at 4:25 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > These patches are on top of driver-core-next.
> >
> > Even if stdout-path isn't set in DT, this patch should take console
> > probe times back to how they were before the deferred_probe_timeout
> > clean up series[1].
>
> Now dropped from my queue due to lack of a response to other reviewer's
> questions.

Sorry, I somehow missed those emails. I'll respond later today/tomorrow.

-Saravana

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Olof Johansson]

On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > These patches are on top of driver-core-next.
> >
> > Even if stdout-path isn't set in DT, this patch should take console
> > probe times back to how they were before the deferred_probe_timeout
> > clean up series[1].
>
> Now dropped from my queue due to lack of a response to other reviewer's
> questions.

What happened to this patch? I have a 10 second timeout on console
probe on my SiFive Unmatched, and I don't see this flag being set for
the serial driver. In fact, I don't see it anywhere in-tree. I can't
seem to locate another patchset from Saravana around this though, so
I'm not sure where to look for a missing piece for the sifive serial
driver.

This is the second boot time regression (this one not fatal, unlike
the Layerscape PCIe one) from the fw_devlink patchset.

Greg, can you revert the whole set for 6.0, please? It's obviously
nowhere near tested enough to go in and I expect we'll see a bunch of
-stable fixups due to this if we let it remain in.

This seems to be one of the worst releases I've encountered in recent
years on my hardware here due to this patchset. :-(


-Olof

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Greg Kroah-Hartman]

On Sun, Sep 18, 2022 at 08:44:27PM -0700, Olof Johansson wrote:
> On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > > These patches are on top of driver-core-next.
> > >
> > > Even if stdout-path isn't set in DT, this patch should take console
> > > probe times back to how they were before the deferred_probe_timeout
> > > clean up series[1].
> >
> > Now dropped from my queue due to lack of a response to other reviewer's
> > questions.
> 
> What happened to this patch? I have a 10 second timeout on console
> probe on my SiFive Unmatched, and I don't see this flag being set for
> the serial driver. In fact, I don't see it anywhere in-tree. I can't
> seem to locate another patchset from Saravana around this though, so
> I'm not sure where to look for a missing piece for the sifive serial
> driver.
> 
> This is the second boot time regression (this one not fatal, unlike
> the Layerscape PCIe one) from the fw_devlink patchset.
> 
> Greg, can you revert the whole set for 6.0, please? It's obviously
> nowhere near tested enough to go in and I expect we'll see a bunch of
> -stable fixups due to this if we let it remain in.

What exactly is "the whole set"?  I have the default option fix queued
up and will send that to Linus later this week (am traveling back from
Plumbers still), but have not heard any problems about any other issues
at all other than your report.

thnaks,

greg k-h

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Olof Johansson]

On Mon, Sep 19, 2022 at 1:44 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Sun, Sep 18, 2022 at 08:44:27PM -0700, Olof Johansson wrote:
> > On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > > > These patches are on top of driver-core-next.
> > > >
> > > > Even if stdout-path isn't set in DT, this patch should take console
> > > > probe times back to how they were before the deferred_probe_timeout
> > > > clean up series[1].
> > >
> > > Now dropped from my queue due to lack of a response to other reviewer's
> > > questions.
> >
> > What happened to this patch? I have a 10 second timeout on console
> > probe on my SiFive Unmatched, and I don't see this flag being set for
> > the serial driver. In fact, I don't see it anywhere in-tree. I can't
> > seem to locate another patchset from Saravana around this though, so
> > I'm not sure where to look for a missing piece for the sifive serial
> > driver.
> >
> > This is the second boot time regression (this one not fatal, unlike
> > the Layerscape PCIe one) from the fw_devlink patchset.
> >
> > Greg, can you revert the whole set for 6.0, please? It's obviously
> > nowhere near tested enough to go in and I expect we'll see a bunch of
> > -stable fixups due to this if we let it remain in.
>
> What exactly is "the whole set"?  I have the default option fix queued
> up and will send that to Linus later this week (am traveling back from
> Plumbers still), but have not heard any problems about any other issues
> at all other than your report.

I stand corrected in this case, the issue on the Hifive Unmatched was
a regression due to a PWM clock change -- I just sent a patch for that
(serial driver fix).

So it seems like as long as the fw_devlink.strict=1 patch is reverted,
things are back to a working state here.

I still struggle with how the fw_devlink patchset is expected to work
though, since DT is expected to describe the hardware configuration,
and it has no knowledge of whether there are drivers that will be
bound to any referenced supplier devnodes. It's not going to work well
to assume that they will always be bound, and to add 10 second
timeouts for those cases isn't a good solution. Seems like the number
of special cases will keep adding up.

The whole design feels like it's falling short, and it's been patched
here and there to deal with the shortcomings, instead of revisiting
the full solution. (The patches are the console one, and another to
deal with nfsroot boots).

As long as it doesn't keep regressing others, I suppose the work to
redesign it can happen in-tree, but it's not usually how we try to do
it for new functionality. Especially since it's still being iterated
on (with active patch sets posted around -rc1 for improvements).

Oh, and one more thing for the future -- the main patch that changes
behavior due to dependency tracking is 2f8c3ae8288e, named "driver
core: Add wait_for_init_devices_probe helper function". It's easy to
overlook this when looking at a list of patches since it's said to
just introduce a helper.


-Olof

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Rob Herring]

On Mon, Sep 19, 2022 at 5:56 PM Olof Johansson <olof@lixom.net> wrote:
>
> On Mon, Sep 19, 2022 at 1:44 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Sun, Sep 18, 2022 at 08:44:27PM -0700, Olof Johansson wrote:
> > > On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > > > > These patches are on top of driver-core-next.
> > > > >
> > > > > Even if stdout-path isn't set in DT, this patch should take console
> > > > > probe times back to how they were before the deferred_probe_timeout
> > > > > clean up series[1].
> > > >
> > > > Now dropped from my queue due to lack of a response to other reviewer's
> > > > questions.
> > >
> > > What happened to this patch? I have a 10 second timeout on console
> > > probe on my SiFive Unmatched, and I don't see this flag being set for
> > > the serial driver. In fact, I don't see it anywhere in-tree. I can't
> > > seem to locate another patchset from Saravana around this though, so
> > > I'm not sure where to look for a missing piece for the sifive serial
> > > driver.
> > >
> > > This is the second boot time regression (this one not fatal, unlike
> > > the Layerscape PCIe one) from the fw_devlink patchset.
> > >
> > > Greg, can you revert the whole set for 6.0, please? It's obviously
> > > nowhere near tested enough to go in and I expect we'll see a bunch of
> > > -stable fixups due to this if we let it remain in.
> >
> > What exactly is "the whole set"?  I have the default option fix queued
> > up and will send that to Linus later this week (am traveling back from
> > Plumbers still), but have not heard any problems about any other issues
> > at all other than your report.
>
> I stand corrected in this case, the issue on the Hifive Unmatched was
> a regression due to a PWM clock change -- I just sent a patch for that
> (serial driver fix).
>
> So it seems like as long as the fw_devlink.strict=1 patch is reverted,
> things are back to a working state here.
>
> I still struggle with how the fw_devlink patchset is expected to work
> though, since DT is expected to describe the hardware configuration,
> and it has no knowledge of whether there are drivers that will be
> bound to any referenced supplier devnodes. It's not going to work well
> to assume that they will always be bound, and to add 10 second
> timeouts for those cases isn't a good solution. Seems like the number
> of special cases will keep adding up.

Since the introduction of deferred probe, the kernel has always
assumed if there is a device described, then there is or will be a
driver for it. The result is you can't use new DTs (if they add
providers) with older kernels.

We've ended up with a timeout because no one has come up with a better
way to handle it. What the kernel needs is userspace saying "I'm done
loading modules", but it's debatable whether that's a good solution
too.

Rob

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Andy Shevchenko]

On Mon, Sep 26, 2022 at 01:25:05PM -0500, Rob Herring wrote:
> On Mon, Sep 19, 2022 at 5:56 PM Olof Johansson <olof@lixom.net> wrote:
> >
> > On Mon, Sep 19, 2022 at 1:44 AM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Sun, Sep 18, 2022 at 08:44:27PM -0700, Olof Johansson wrote:
> > > > On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
> > > > <gregkh@linuxfoundation.org> wrote:
> > > > >
> > > > > On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > > > > > These patches are on top of driver-core-next.
> > > > > >
> > > > > > Even if stdout-path isn't set in DT, this patch should take console
> > > > > > probe times back to how they were before the deferred_probe_timeout
> > > > > > clean up series[1].
> > > > >
> > > > > Now dropped from my queue due to lack of a response to other reviewer's
> > > > > questions.
> > > >
> > > > What happened to this patch? I have a 10 second timeout on console
> > > > probe on my SiFive Unmatched, and I don't see this flag being set for
> > > > the serial driver. In fact, I don't see it anywhere in-tree. I can't
> > > > seem to locate another patchset from Saravana around this though, so
> > > > I'm not sure where to look for a missing piece for the sifive serial
> > > > driver.
> > > >
> > > > This is the second boot time regression (this one not fatal, unlike
> > > > the Layerscape PCIe one) from the fw_devlink patchset.
> > > >
> > > > Greg, can you revert the whole set for 6.0, please? It's obviously
> > > > nowhere near tested enough to go in and I expect we'll see a bunch of
> > > > -stable fixups due to this if we let it remain in.
> > >
> > > What exactly is "the whole set"?  I have the default option fix queued
> > > up and will send that to Linus later this week (am traveling back from
> > > Plumbers still), but have not heard any problems about any other issues
> > > at all other than your report.
> >
> > I stand corrected in this case, the issue on the Hifive Unmatched was
> > a regression due to a PWM clock change -- I just sent a patch for that
> > (serial driver fix).
> >
> > So it seems like as long as the fw_devlink.strict=1 patch is reverted,
> > things are back to a working state here.
> >
> > I still struggle with how the fw_devlink patchset is expected to work
> > though, since DT is expected to describe the hardware configuration,
> > and it has no knowledge of whether there are drivers that will be
> > bound to any referenced supplier devnodes. It's not going to work well
> > to assume that they will always be bound, and to add 10 second
> > timeouts for those cases isn't a good solution. Seems like the number
> > of special cases will keep adding up.
> 
> Since the introduction of deferred probe, the kernel has always
> assumed if there is a device described, then there is or will be a
> driver for it. The result is you can't use new DTs (if they add
> providers) with older kernels.
> 
> We've ended up with a timeout because no one has come up with a better
> way to handle it. What the kernel needs is userspace saying "I'm done
> loading modules", but it's debatable whether that's a good solution
> too.

In my opinion the deferred probe is a big hack and that is the root
cause of the issues we have here and there. It has to be redesigned
to be mathematically robust. It was an attempt by Andrzej Hajda to
solve this [1].

[1]: https://events19.linuxfoundation.org/wp-content/uploads/2017/12/Deferred-Problem-Issues-With-Complex-Dependencies-Between-Devices-in-Linux-Kernel-Andrzej-Hajda-Samsung.pdf

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 0/2] Fix console probe delay when stdout-path isn't set

[Greg Kroah-Hartman]

On Tue, Sep 27, 2022 at 03:17:59PM +0300, Andy Shevchenko wrote:
> On Mon, Sep 26, 2022 at 01:25:05PM -0500, Rob Herring wrote:
> > On Mon, Sep 19, 2022 at 5:56 PM Olof Johansson <olof@lixom.net> wrote:
> > >
> > > On Mon, Sep 19, 2022 at 1:44 AM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Sun, Sep 18, 2022 at 08:44:27PM -0700, Olof Johansson wrote:
> > > > > On Tue, Aug 23, 2022 at 8:37 AM Greg Kroah-Hartman
> > > > > <gregkh@linuxfoundation.org> wrote:
> > > > > >
> > > > > > On Thu, Jun 30, 2022 at 06:26:38PM -0700, Saravana Kannan wrote:
> > > > > > > These patches are on top of driver-core-next.
> > > > > > >
> > > > > > > Even if stdout-path isn't set in DT, this patch should take console
> > > > > > > probe times back to how they were before the deferred_probe_timeout
> > > > > > > clean up series[1].
> > > > > >
> > > > > > Now dropped from my queue due to lack of a response to other reviewer's
> > > > > > questions.
> > > > >
> > > > > What happened to this patch? I have a 10 second timeout on console
> > > > > probe on my SiFive Unmatched, and I don't see this flag being set for
> > > > > the serial driver. In fact, I don't see it anywhere in-tree. I can't
> > > > > seem to locate another patchset from Saravana around this though, so
> > > > > I'm not sure where to look for a missing piece for the sifive serial
> > > > > driver.
> > > > >
> > > > > This is the second boot time regression (this one not fatal, unlike
> > > > > the Layerscape PCIe one) from the fw_devlink patchset.
> > > > >
> > > > > Greg, can you revert the whole set for 6.0, please? It's obviously
> > > > > nowhere near tested enough to go in and I expect we'll see a bunch of
> > > > > -stable fixups due to this if we let it remain in.
> > > >
> > > > What exactly is "the whole set"?  I have the default option fix queued
> > > > up and will send that to Linus later this week (am traveling back from
> > > > Plumbers still), but have not heard any problems about any other issues
> > > > at all other than your report.
> > >
> > > I stand corrected in this case, the issue on the Hifive Unmatched was
> > > a regression due to a PWM clock change -- I just sent a patch for that
> > > (serial driver fix).
> > >
> > > So it seems like as long as the fw_devlink.strict=1 patch is reverted,
> > > things are back to a working state here.
> > >
> > > I still struggle with how the fw_devlink patchset is expected to work
> > > though, since DT is expected to describe the hardware configuration,
> > > and it has no knowledge of whether there are drivers that will be
> > > bound to any referenced supplier devnodes. It's not going to work well
> > > to assume that they will always be bound, and to add 10 second
> > > timeouts for those cases isn't a good solution. Seems like the number
> > > of special cases will keep adding up.
> > 
> > Since the introduction of deferred probe, the kernel has always
> > assumed if there is a device described, then there is or will be a
> > driver for it. The result is you can't use new DTs (if they add
> > providers) with older kernels.
> > 
> > We've ended up with a timeout because no one has come up with a better
> > way to handle it. What the kernel needs is userspace saying "I'm done
> > loading modules", but it's debatable whether that's a good solution
> > too.
> 
> In my opinion the deferred probe is a big hack and that is the root
> cause of the issues we have here and there. It has to be redesigned
> to be mathematically robust. It was an attempt by Andrzej Hajda to
> solve this [1].
> 
> [1]: https://events19.linuxfoundation.org/wp-content/uploads/2017/12/Deferred-Problem-Issues-With-Complex-Dependencies-Between-Devices-in-Linux-Kernel-Andrzej-Hajda-Samsung.pdf

deferred probe has _ALWAYS_ been known to be a hack, way back when we
accepted it, but it was the best hack we had to solve a real problem
that we had, so it was accepted.

It's been polished over the years, but yes, it does break down at times,
due to the crazy complexity of hardware systems that we have no control
over.

If you have concrete solutions for how to solve the issue, wonderful,
please submit patches :)

thanks,

greg k-h