[PATCH v2 1/2] serial: 8250: SERIAL_8250_FSL should not default to y when compile-testing

Commit b1442c55ce8977aa ("serial: 8250: extend compile-test coverage")
added compile-test support to the Freescale 16550 driver.  However, as
SERIAL_8250_FSL is an invisible symbol, merely enabling compile-testing
now enables this driver.

Fix this by dropping the COMPILE_TEST default again, but making the
SERIAL_8250_FSL symbol visible instead.

Fixes: b1442c55ce8977aa ("serial: 8250: extend compile-test coverage")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - Split in two parts.
---
 drivers/tty/serial/8250/Kconfig | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 808268edd2e82a45..0af96f3adab517f6 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig

@@ -361,9 +361,12 @@ config SERIAL_8250_BCM2835AUX
 	  If unsure, say N.
 
 config SERIAL_8250_FSL
-	bool
+	bool "Freescale 16550-style UART support (8250 based driver)"
 	depends on SERIAL_8250_CONSOLE
-	default PPC || ARM || ARM64 || COMPILE_TEST
+	default PPC || ARM || ARM64
+	help
+	  Selecting this option will add support for the 16550-style serial
+	  port hardware found on Freescale SoCs.
 
 config SERIAL_8250_DW
 	tristate "Support for Synopsys DesignWare 8250 quirks"

-- 
2.25.1

The Freescale 16550-style UART is only present on some Freescale SoCs.
Hence tighten the dependencies to prevent asking the user about this
driver, and possibly defaulting it to be enabled, when configuring a
kernel without appropriate Freescale SoC or ACPI support.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - Split in two parts.
---
 drivers/tty/serial/8250/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 0af96f3adab517f6..a2978b31144e94f2 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig

@@ -363,7 +363,8 @@ config SERIAL_8250_BCM2835AUX
 config SERIAL_8250_FSL
 	bool "Freescale 16550-style UART support (8250 based driver)"
 	depends on SERIAL_8250_CONSOLE
-	default PPC || ARM || ARM64
+	depends on FSL_SOC || ARCH_LAYERSCAPE || SOC_LS1021A || (ARM64 && ACPI) || COMPILE_TEST
+	default FSL_SOC || ARCH_LAYERSCAPE || SOC_LS1021A || (ARM64 && ACPI)
 	help
 	  Selecting this option will add support for the 16550-style serial
 	  port hardware found on Freescale SoCs.

-- 
2.25.1

On Fri, Sep 24, 2021 at 09:12:30AM +0200, Geert Uytterhoeven wrote:

Commit b1442c55ce8977aa ("serial: 8250: extend compile-test coverage")
added compile-test support to the Freescale 16550 driver.  However, as
SERIAL_8250_FSL is an invisible symbol, merely enabling compile-testing
now enables this driver.

Fix this by dropping the COMPILE_TEST default again, but making the
SERIAL_8250_FSL symbol visible instead.

Fixes: b1442c55ce8977aa ("serial: 8250: extend compile-test coverage")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - Split in two parts.

I realised that we can do better than this. I've prepared a patch that
preserves the old behaviour of always enabling the option on platforms
that may need it while also not enabling it by default when compile
testing.

Note that SERIAL_8250_FSL only enables a workaround for an erratum in
the Freescale UARTs in the 8250 driver (leaving the later added ACPI
support aside) and we shouldn't make it easier to disable it by mistake.

Johan