[PATCH] ARM: dts: am33xx: Add missing serial console speed

[PATCH] ARM: dts: am33xx: Add missing serial console speed

[Geert Uytterhoeven]

Without a serial console speed specified in chosen/stdout-path in the
DTB, the serial console uses the default speed of the serial driver,
unless explicitly overridden in a legacy console= kernel command-line
parameter.

After dropping "ti,omap3-uart" from the list of compatible values in DT,
AM33xx serial ports can no longer be used with the legacy OMAP serial
driver, but only with the OMAP-flavored 8250 serial driver (which is
mutually-exclusive with the former).  However, replacing
CONFIG_SERIAL_OMAP=y by CONFIG_SERIAL_8250_OMAP=y (with/without enabling
CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP) may not be sufficient to restore
serial console functionality: the legacy OMAP serial driver defaults to
115200 bps, while the 8250 serial driver defaults to 9600 bps, causing
no visible output on the serial console when no appropriate console=
kernel command-line parameter is specified.

Fix this for all AM33xx boards by adding ":115200n8" to
chosen/stdout-path.  This requires replacing the "&uartN" reference by
the corresponding "serialN" DT alias.

Fixes: ca8be8fc2c306efb ("ARM: dts: am33xx-l4: fix UART compatible")
Fixes: 077e1cde78c3f904 ("ARM: omap2plus_defconfig: Enable 8250_OMAP")
Closes: https://lore.kernel.org/CAMuHMdUb7Jb2=GqK3=Rn+Gv5G9KogcQieqDvjDCkJA4zyX4VcA@mail.gmail.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Tested on BeagleBone Black.
I only updated DTS files affected by commit ca8be8fc2c306efb.
Probably more DTS files for other SoCs should be updated, too.
---
 arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi   | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-boneblue.dts       | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-chiliboard.dts     | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-evm.dts            | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-evmsk.dts          | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-guardian.dts       | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-icev2.dts          | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-myirtech-myd.dts   | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-osd3358-sm-red.dts | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-pdu001.dts         | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-pocketbeagle.dts   | 2 +-
 arch/arm/boot/dts/ti/omap/am335x-sl50.dts           | 2 +-
 12 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi b/arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi
index ad1e60a9b6fde8f9..b75dabfa56ae7605 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi
+++ b/arch/arm/boot/dts/ti/omap/am335x-bone-common.dtsi
@@ -16,7 +16,7 @@ memory@80000000 {
 	};
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-boneblue.dts b/arch/arm/boot/dts/ti/omap/am335x-boneblue.dts
index f579df4c2c540dd7..d430f0bef1653782 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-boneblue.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-boneblue.dts
@@ -13,7 +13,7 @@ / {
 	compatible = "ti,am335x-bone-blue", "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-chiliboard.dts b/arch/arm/boot/dts/ti/omap/am335x-chiliboard.dts
index 648e97fe1dfd5e5b..ae5bc589849722f5 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-chiliboard.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-chiliboard.dts
@@ -12,7 +12,7 @@ / {
 		     "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-evm.dts b/arch/arm/boot/dts/ti/omap/am335x-evm.dts
index 20222f82f21bfd9d..856fa1191ed24ea3 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-evm.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-evm.dts
@@ -23,7 +23,7 @@ memory@80000000 {
 	};
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	vbat: fixedregulator0 {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-evmsk.dts b/arch/arm/boot/dts/ti/omap/am335x-evmsk.dts
index eba888dcd60e7fa2..d8baccdf8bc46302 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-evmsk.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-evmsk.dts
@@ -30,7 +30,7 @@ memory@80000000 {
 	};
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	vbat: fixedregulator0 {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-guardian.dts b/arch/arm/boot/dts/ti/omap/am335x-guardian.dts
index 4b070e634b28100b..6ce3a2d029eedc8c 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-guardian.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-guardian.dts
@@ -14,7 +14,7 @@ / {
 	compatible = "bosch,am335x-guardian", "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 		tick-timer = &timer2;
 	};
 
diff --git a/arch/arm/boot/dts/ti/omap/am335x-icev2.dts b/arch/arm/boot/dts/ti/omap/am335x-icev2.dts
index 6f0f4fba043b96e9..ba488bba6925dec3 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-icev2.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-icev2.dts
@@ -22,7 +22,7 @@ memory@80000000 {
 	};
 
 	chosen {
-		stdout-path = &uart3;
+		stdout-path = "serial3:115200n8";
 	};
 
 	vbat: fixedregulator0 {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-myirtech-myd.dts b/arch/arm/boot/dts/ti/omap/am335x-myirtech-myd.dts
index 06a352f98b220bc4..476a6bdaf43f38e4 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-myirtech-myd.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-myirtech-myd.dts
@@ -15,7 +15,7 @@ / {
 	compatible = "myir,myd-am335x", "myir,myc-am335x", "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	clk12m: clk12m {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-osd3358-sm-red.dts b/arch/arm/boot/dts/ti/omap/am335x-osd3358-sm-red.dts
index d28d397288476504..23caaaabf35134a6 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-osd3358-sm-red.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-osd3358-sm-red.dts
@@ -147,7 +147,7 @@ simple-audio-card,codec {
 	};
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-pdu001.dts b/arch/arm/boot/dts/ti/omap/am335x-pdu001.dts
index c9ccb9de21ad7b10..9f611debc209072c 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-pdu001.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-pdu001.dts
@@ -21,7 +21,7 @@ / {
 	compatible = "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart3;
+		stdout-path = "serial3:115200n8";
 	};
 
 	cpus {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-pocketbeagle.dts b/arch/arm/boot/dts/ti/omap/am335x-pocketbeagle.dts
index 78ce860e59b3de4f..24d9f90fad01f768 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-pocketbeagle.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-pocketbeagle.dts
@@ -15,7 +15,7 @@ / {
 	compatible = "ti,am335x-pocketbeagle", "ti,am335x-bone", "ti,am33xx";
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
diff --git a/arch/arm/boot/dts/ti/omap/am335x-sl50.dts b/arch/arm/boot/dts/ti/omap/am335x-sl50.dts
index f3524e5ee43e276d..1dc4e344efd63e4e 100644
--- a/arch/arm/boot/dts/ti/omap/am335x-sl50.dts
+++ b/arch/arm/boot/dts/ti/omap/am335x-sl50.dts
@@ -25,7 +25,7 @@ memory@80000000 {
 	};
 
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = "serial0:115200n8";
 	};
 
 	leds {
-- 
2.43.0

Re: [PATCH] ARM: dts: am33xx: Add missing serial console speed

[Matti Vaittinen]

On 02/10/2025 12:53, Geert Uytterhoeven wrote:
> Without a serial console speed specified in chosen/stdout-path in the
> DTB, the serial console uses the default speed of the serial driver,
> unless explicitly overridden in a legacy console= kernel command-line
> parameter.
> 
> After dropping "ti,omap3-uart" from the list of compatible values in DT,
> AM33xx serial ports can no longer be used with the legacy OMAP serial
> driver, but only with the OMAP-flavored 8250 serial driver (which is
> mutually-exclusive with the former).  However, replacing
> CONFIG_SERIAL_OMAP=y by CONFIG_SERIAL_8250_OMAP=y (with/without enabling
> CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP) may not be sufficient to restore
> serial console functionality: the legacy OMAP serial driver defaults to
> 115200 bps, while the 8250 serial driver defaults to 9600 bps, causing
> no visible output on the serial console when no appropriate console=
> kernel command-line parameter is specified.
> 
> Fix this for all AM33xx boards by adding ":115200n8" to
> chosen/stdout-path.  This requires replacing the "&uartN" reference by
> the corresponding "serialN" DT alias.
> 
> Fixes: ca8be8fc2c306efb ("ARM: dts: am33xx-l4: fix UART compatible")
> Fixes: 077e1cde78c3f904 ("ARM: omap2plus_defconfig: Enable 8250_OMAP")
> Closes: https://lore.kernel.org/CAMuHMdUb7Jb2=GqK3=Rn+Gv5G9KogcQieqDvjDCkJA4zyX4VcA@mail.gmail.com
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Tested-by: Matti Vaittinen <mazziesaccount@gmail.com>

(Tested booting on Beaglebone black with a config and kernel command 
line which were NOT affected by the issue. Well, prints do still get 
through the UART to my minicom, so things seem to work for me after this 
change as well :) )

The change does also look Ok to me.

Yours,
	-- Matti

Re: [PATCH] ARM: dts: am33xx: Add missing serial console speed

[Bruno Thomsen]

Den tors. 2. okt. 2025 kl. 14.32 skrev Matti Vaittinen
<mazziesaccount@gmail.com>:
>
> On 02/10/2025 12:53, Geert Uytterhoeven wrote:
> > Without a serial console speed specified in chosen/stdout-path in the
> > DTB, the serial console uses the default speed of the serial driver,
> > unless explicitly overridden in a legacy console= kernel command-line
> > parameter.
> >
> > After dropping "ti,omap3-uart" from the list of compatible values in DT,
> > AM33xx serial ports can no longer be used with the legacy OMAP serial
> > driver, but only with the OMAP-flavored 8250 serial driver (which is
> > mutually-exclusive with the former).  However, replacing
> > CONFIG_SERIAL_OMAP=y by CONFIG_SERIAL_8250_OMAP=y (with/without enabling
> > CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP) may not be sufficient to restore
> > serial console functionality: the legacy OMAP serial driver defaults to
> > 115200 bps, while the 8250 serial driver defaults to 9600 bps, causing
> > no visible output on the serial console when no appropriate console=
> > kernel command-line parameter is specified.
> >
> > Fix this for all AM33xx boards by adding ":115200n8" to
> > chosen/stdout-path.  This requires replacing the "&uartN" reference by
> > the corresponding "serialN" DT alias.
> >
> > Fixes: ca8be8fc2c306efb ("ARM: dts: am33xx-l4: fix UART compatible")
> > Fixes: 077e1cde78c3f904 ("ARM: omap2plus_defconfig: Enable 8250_OMAP")
> > Closes: https://lore.kernel.org/CAMuHMdUb7Jb2=GqK3=Rn+Gv5G9KogcQieqDvjDCkJA4zyX4VcA@mail.gmail.com
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
> Tested-by: Matti Vaittinen <mazziesaccount@gmail.com>

Reviewed-by: Bruno Thomsen <bruno.thomsen@gmail.com>

>
> (Tested booting on Beaglebone black with a config and kernel command
> line which were NOT affected by the issue. Well, prints do still get
> through the UART to my minicom, so things seem to work for me after this
> change as well :) )
>
> The change does also look Ok to me.
>
> Yours,
>         -- Matti

Re: [PATCH] ARM: dts: am33xx: Add missing serial console speed

[Kevin Hilman]

On Thu, 02 Oct 2025 11:53:05 +0200, Geert Uytterhoeven wrote:
> Without a serial console speed specified in chosen/stdout-path in the
> DTB, the serial console uses the default speed of the serial driver,
> unless explicitly overridden in a legacy console= kernel command-line
> parameter.
> 
> After dropping "ti,omap3-uart" from the list of compatible values in DT,
> AM33xx serial ports can no longer be used with the legacy OMAP serial
> driver, but only with the OMAP-flavored 8250 serial driver (which is
> mutually-exclusive with the former).  However, replacing
> CONFIG_SERIAL_OMAP=y by CONFIG_SERIAL_8250_OMAP=y (with/without enabling
> CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP) may not be sufficient to restore
> serial console functionality: the legacy OMAP serial driver defaults to
> 115200 bps, while the 8250 serial driver defaults to 9600 bps, causing
> no visible output on the serial console when no appropriate console=
> kernel command-line parameter is specified.
> 
> [...]

Applied, thanks!

[1/1] ARM: dts: am33xx: Add missing serial console speed
      commit: 9c95fc710b0d05f797db9e26d56524efa74f8978

Best regards,
-- 
Kevin Hilman <khilman@baylibre.com>