These drivers were added about 3 years ago, and depend on the
XTENSA_PLATFORM_ESP32 config option which has never existed,
so no device can actually use them.
They can only be compiled with COMPILE_TEST.

As you can see, this config option is still undefined
in the downstream tree:
https://github.com/search?q=repo%3Ajcmvbkbc%2Flinux-xtensa%20XTENSA_PLATFORM_ESP32&type=code

I propose moving these drivers into staging
until there is a device that can boot the mainline kernel and use them.

Signed-off-by: Julian Braha <julianbraha@gmail.com>
---
 drivers/staging/Kconfig                       |  2 ++
 drivers/staging/Makefile                      |  1 +
 drivers/staging/serial_esp32/Kconfig          | 28 +++++++++++++++++++
 drivers/staging/serial_esp32/Makefile         |  4 +++
 .../serial_esp32}/esp32_acm.c                 |  0
 .../serial_esp32}/esp32_uart.c                |  0
 drivers/tty/serial/Kconfig                    | 26 -----------------
 drivers/tty/serial/Makefile                   |  2 --
 8 files changed, 35 insertions(+), 28 deletions(-)
 create mode 100644 drivers/staging/serial_esp32/Kconfig
 create mode 100644 drivers/staging/serial_esp32/Makefile
 rename drivers/{tty/serial => staging/serial_esp32}/esp32_acm.c (100%)
 rename drivers/{tty/serial => staging/serial_esp32}/esp32_uart.c (100%)

diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 2f92cd698bef..97593e31ca47 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -48,4 +48,6 @@ source "drivers/staging/axis-fifo/Kconfig"
 
 source "drivers/staging/vme_user/Kconfig"
 
+source "drivers/staging/serial_esp32/Kconfig"
+
 endif # STAGING
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index f5b8876aa536..78c2e4f49fe5 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -2,6 +2,7 @@
 # Makefile for staging directory
 
 obj-y				+= media/
+obj-y				+= serial_esp32/
 obj-$(CONFIG_RTL8723BS)		+= rtl8723bs/
 obj-$(CONFIG_OCTEON_ETHERNET)	+= octeon/
 obj-$(CONFIG_VME_BUS)		+= vme_user/
diff --git a/drivers/staging/serial_esp32/Kconfig b/drivers/staging/serial_esp32/Kconfig
new file mode 100644
index 000000000000..61c56bfe7764
--- /dev/null
+++ b/drivers/staging/serial_esp32/Kconfig
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0
+config SERIAL_ESP32
+	tristate "Espressif ESP32 UART support"
+	depends on HAS_IOMEM
+	depends on XTENSA_PLATFORM_ESP32 || (COMPILE_TEST && OF)
+	select SERIAL_CORE
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Driver for the UART controllers of the Espressif ESP32xx SoCs.
+	  When earlycon option is enabled the following kernel command line
+	  snippets may be used:
+	    earlycon=esp32s3uart,mmio32,0x60000000,115200n8,40000000
+	    earlycon=esp32uart,mmio32,0x3ff40000,115200n8
+
+config SERIAL_ESP32_ACM
+	tristate "Espressif ESP32 USB ACM gadget support"
+	depends on HAS_IOMEM
+	depends on XTENSA_PLATFORM_ESP32 || (COMPILE_TEST && OF)
+	select SERIAL_CORE
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Driver for the CDC ACM gadget controller of the Espressif ESP32S3
+	  SoCs that share separate USB controller with the JTAG adapter.
+	  When earlycon option is enabled the following kernel command line
+	  snippet may be used:
+	    earlycon=esp32s3acm,mmio32,0x60038000
diff --git a/drivers/staging/serial_esp32/Makefile b/drivers/staging/serial_esp32/Makefile
new file mode 100644
index 000000000000..3c23321944e2
--- /dev/null
+++ b/drivers/staging/serial_esp32/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_SERIAL_ESP32)		+= esp32_uart.o
+obj-$(CONFIG_SERIAL_ESP32_ACM)		+= esp32_acm.o
diff --git a/drivers/tty/serial/esp32_acm.c b/drivers/staging/serial_esp32/esp32_acm.c
similarity index 100%
rename from drivers/tty/serial/esp32_acm.c
rename to drivers/staging/serial_esp32/esp32_acm.c
diff --git a/drivers/tty/serial/esp32_uart.c b/drivers/staging/serial_esp32/esp32_uart.c
similarity index 100%
rename from drivers/tty/serial/esp32_uart.c
rename to drivers/staging/serial_esp32/esp32_uart.c
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index f86775cfdcc9..686e7fb073b8 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1593,32 +1593,6 @@ config SERIAL_NUVOTON_MA35D1_CONSOLE
 	  but you can alter that using a kernel command line option such as
 	  "console=ttyNVTx".
 
-config SERIAL_ESP32
-	tristate "Espressif ESP32 UART support"
-	depends on XTENSA_PLATFORM_ESP32 || (COMPILE_TEST && OF)
-	select SERIAL_CORE
-	select SERIAL_CORE_CONSOLE
-	select SERIAL_EARLYCON
-	help
-	  Driver for the UART controllers of the Espressif ESP32xx SoCs.
-	  When earlycon option is enabled the following kernel command line
-	  snippets may be used:
-	    earlycon=esp32s3uart,mmio32,0x60000000,115200n8,40000000
-	    earlycon=esp32uart,mmio32,0x3ff40000,115200n8
-
-config SERIAL_ESP32_ACM
-	tristate "Espressif ESP32 USB ACM gadget support"
-	depends on XTENSA_PLATFORM_ESP32 || (COMPILE_TEST && OF)
-	select SERIAL_CORE
-	select SERIAL_CORE_CONSOLE
-	select SERIAL_EARLYCON
-	help
-	  Driver for the CDC ACM gadget controller of the Espressif ESP32S3
-	  SoCs that share separate USB controller with the JTAG adapter.
-	  When earlycon option is enabled the following kernel command line
-	  snippet may be used:
-	    earlycon=esp32s3acm,mmio32,0x60038000
-
 endmenu
 
 config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index a2ccbc508ec5..bba7b21a4a1d 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -37,8 +37,6 @@ obj-$(CONFIG_SERIAL_CLPS711X)		+= clps711x.o
 obj-$(CONFIG_SERIAL_CPM)		+= cpm_uart.o
 obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR)	+= digicolor-usart.o
 obj-$(CONFIG_SERIAL_DZ)			+= dz.o
-obj-$(CONFIG_SERIAL_ESP32)		+= esp32_uart.o
-obj-$(CONFIG_SERIAL_ESP32_ACM)		+= esp32_acm.o
 obj-$(CONFIG_SERIAL_FSL_LINFLEXUART)	+= fsl_linflexuart.o
 obj-$(CONFIG_SERIAL_FSL_LPUART)		+= fsl_lpuart.o
 obj-$(CONFIG_SERIAL_ICOM)		+= icom.o
-- 
2.51.2

On Sun, Mar 08, 2026 at 01:14:12PM +0000, Julian Braha wrote:
> These drivers were added about 3 years ago, and depend on the
> XTENSA_PLATFORM_ESP32 config option which has never existed,
> so no device can actually use them.
> They can only be compiled with COMPILE_TEST.
> 
> As you can see, this config option is still undefined
> in the downstream tree:
> https://github.com/search?q=repo%3Ajcmvbkbc%2Flinux-xtensa%20XTENSA_PLATFORM_ESP32&type=code
> 
> I propose moving these drivers into staging
> until there is a device that can boot the mainline kernel and use them.

Why not just delete them?  What can staging do to help out here?  If
these can't be built, or used, don't drop them in staging, that's not
what that part of the kernel is for, sorry.

thanks,

greg k-h

On Sun, Mar 8, 2026 at 7:16 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> On Sun, Mar 08, 2026 at 01:14:12PM +0000, Julian Braha wrote:
> > These drivers were added about 3 years ago, and depend on the
> > XTENSA_PLATFORM_ESP32 config option which has never existed,
> > so no device can actually use them.
> > They can only be compiled with COMPILE_TEST.
> >
> > As you can see, this config option is still undefined
> > in the downstream tree:
> > https://github.com/search?q=repo%3Ajcmvbkbc%2Flinux-xtensa%20XTENSA_PLATFORM_ESP32&type=code
> >
> > I propose moving these drivers into staging
> > until there is a device that can boot the mainline kernel and use them.
>
> Why not just delete them?

I agree, it should go. I haven't had a chance to get back to it in 2 years,
and it doesn't look like I will any time soon.

-- 
Thanks.
-- Max