linux-kernel - Re: [PATCH v2 1/1] serial: 8250_ce4100: Fix CONFIG_SERIAL

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Message-ID: <1edd39a3-c5ef-41f6-ba7a-57fe24da7376@infradead.org>
Date: Wed, 16 Jul 2025 12:16:59 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Cc: Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v2 1/1] serial: 8250_ce4100: Fix CONFIG_SERIAL_8250=n
 build



On 7/16/25 7:23 AM, Andy Shevchenko wrote:
> On i386, when
> 
>   CONFIG_X86_INTEL_CE=y
>   # CONFIG_SERIAL_8250 is not set
> 
> it will try to compile the driver and use the stub simultaneously.
> This breaks the build. Fix it by making sure that the driver
> compiles only when CONFIG_SERIAL_8250 is also enabled.
> 
> On top of that ensure that CONFIG_SERIAL_8250 is actually set to 'y'
> and not 'm' as the later makes no sense for this platform. The hook
> may only be applied during early boot.
> 
> Fixes: acc902de05b2 ("serial: 8250: Move CE4100 quirks to a module under 8250 driver")
> Fixes: 5ec6960f6f0c ("ce4100: Add errata fixes for UART on CE4100")
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Closes: https://lore.kernel.org/r/cdf4ee46-7bf8-4379-9245-fed9db72e7e8@infradead.org
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

This solution works but it seems quite hidden to me. I would rather see
a Kconfig solution, like Jiri mentioned.

Anyway,
Acked-by: Randy Dunlap <rdunlap@...radead.org>
Tested-by: Randy Dunlap <rdunlap@...radead.org>


Thanks.

> ---
> 
> v2: made the fix more readable (Jiri)
> 
>  drivers/tty/serial/8250/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
> index e61dc3f4ca50..513a0941c284 100644
> --- a/drivers/tty/serial/8250/Makefile
> +++ b/drivers/tty/serial/8250/Makefile
> @@ -24,7 +24,9 @@ obj-$(CONFIG_SERIAL_8250_ASPEED_VUART)	+= 8250_aspeed_vuart.o
>  obj-$(CONFIG_SERIAL_8250_BCM2835AUX)	+= 8250_bcm2835aux.o
>  obj-$(CONFIG_SERIAL_8250_BCM7271)	+= 8250_bcm7271.o
>  obj-$(CONFIG_SERIAL_8250_BOCA)		+= 8250_boca.o
> +ifeq ($(CONFIG_SERIAL_8250),y)
>  obj-$(CONFIG_X86_INTEL_CE)		+= 8250_ce4100.o
> +endif
>  obj-$(CONFIG_SERIAL_8250_DFL)		+= 8250_dfl.o
>  obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
>  obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o

-- 
~Randy