5.10-stable patches

added patches:
	serial-sh-sci-increment-the-runtime-usage-counter-for-the-earlycon-device.patch

diff --git a/queue-5.10/serial-sh-sci-increment-the-runtime-usage-counter-for-the-earlycon-device.patch b/queue-5.10/serial-sh-sci-increment-the-runtime-usage-counter-for-the-earlycon-device.patch
new file mode 100644 (file)
index 0000000..c3dbafd
--- /dev/null
+++ b/queue-5.10/serial-sh-sci-increment-the-runtime-usage-counter-for-the-earlycon-device.patch
@@ -0,0 +1,85 @@
+From 651dee03696e1dfde6d9a7e8664bbdcd9a10ea7f Mon Sep 17 00:00:00 2001
+From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
+Date: Thu, 16 Jan 2025 20:22:49 +0200
+Subject: serial: sh-sci: Increment the runtime usage counter for the earlycon device
+
+From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
+
+commit 651dee03696e1dfde6d9a7e8664bbdcd9a10ea7f upstream.
+
+In the sh-sci driver, serial ports are mapped to the sci_ports[] array,
+with earlycon mapped at index zero.
+
+The uart_add_one_port() function eventually calls __device_attach(),
+which, in turn, calls pm_request_idle(). The identified code path is as
+follows:
+
+uart_add_one_port() ->
+  serial_ctrl_register_port() ->
+    serial_core_register_port() ->
+      serial_core_port_device_add() ->
+        serial_base_port_add() ->
+          device_add() ->
+            bus_probe_device() ->
+              device_initial_probe() ->
+                __device_attach() ->
+                  // ...
+                  if (dev->p->dead) {
+                    // ...
+                  } else if (dev->driver) {
+                    // ...
+                  } else {
+                    // ...
+                    pm_request_idle(dev);
+                    // ...
+                  }
+
+The earlycon device clocks are enabled by the bootloader. However, the
+pm_request_idle() call in __device_attach() disables the SCI port clocks
+while earlycon is still active.
+
+The earlycon write function, serial_console_write(), calls
+sci_poll_put_char() via serial_console_putchar(). If the SCI port clocks
+are disabled, writing to earlycon may sometimes cause the SR.TDFE bit to
+remain unset indefinitely, causing the while loop in sci_poll_put_char()
+to never exit. On single-core SoCs, this can result in the system being
+blocked during boot when this issue occurs.
+
+To resolve this, increment the runtime PM usage counter for the earlycon
+SCI device before registering the UART port.
+
+Fixes: 0b0cced19ab1 ("serial: sh-sci: Add CONFIG_SERIAL_EARLYCON support")
+Cc: stable@vger.kernel.org
+Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
+Link: https://lore.kernel.org/r/20250116182249.3828577-6-claudiu.beznea.uj@bp.renesas.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/serial/sh-sci.c |   16 ++++++++++++++++
+ 1 file changed, 16 insertions(+)
+
+--- a/drivers/tty/serial/sh-sci.c
++++ b/drivers/tty/serial/sh-sci.c
+@@ -3359,6 +3359,22 @@ static int sci_probe_single(struct platf
+ 
+       if (sci_uart_earlycon && sci_ports[0].port.mapbase == sci_res->start) {
+               /*
++               * In case:
++               * - this is the earlycon port (mapped on index 0 in sci_ports[]) and
++               * - it now maps to an alias other than zero and
++               * - the earlycon is still alive (e.g., "earlycon keep_bootcon" is
++               *   available in bootargs)
++               *
++               * we need to avoid disabling clocks and PM domains through the runtime
++               * PM APIs called in __device_attach(). For this, increment the runtime
++               * PM reference counter (the clocks and PM domains were already enabled
++               * by the bootloader). Otherwise the earlycon may access the HW when it
++               * has no clocks enabled leading to failures (infinite loop in
++               * sci_poll_put_char()).
++               */
++              pm_runtime_get_noresume(&dev->dev);
++
++              /*
+                * Skip cleanup the sci_port[0] in early_console_exit(), this
+                * port is the same as the earlycon one.
+                */

diff --git a/queue-5.10/series b/queue-5.10/series
index b5aa45452926b3d10730554c7f2392961df2c28c..43743d644db798efa8f58505043f1e7af88286e7 100644 (file)
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -319,3 +319,4 @@ net-atm-fix-proc-net-atm-lec-handling.patch
 arm-dts-am335x-bone-common-add-gpio-phy-reset-on-revision-c3-board.patch
 arm-dts-am335x-bone-common-increase-mdio-reset-deassert-time.patch
 arm-dts-am335x-bone-common-increase-mdio-reset-deassert-delay-to-50ms.patch
+serial-sh-sci-increment-the-runtime-usage-counter-for-the-earlycon-device.patch