[PATCH v3 4/6] serial: Implement serial_flush() function for console flush() fallback

[Pali Rohár]

On Tuesday 20 September 2022 17:40:39 Tom Rini wrote:
> On Mon, Sep 05, 2022 at 11:31:19AM +0200, Pali Rohár wrote:
> 
> > Like in all other console functions, implement also serial_flush() function
> > as a fallback int console flush() function.
> > 
> > Flush support is available only when config option CONSOLE_FLUSH_SUPPORT is
> > enabled. So when it is disabled then provides just empty static inline
> > function serial_flush().
> > 
> > Signed-off-by: Pali Rohár <pali at kernel.org>
> > Reviewed-by: Simon Glass <sjg at chromium.org>
> 
> This breaks building on a number of platforms such as ds109 probably due
> to DM_SERIAL not being enabled.

ds109 is failing on error:

  LD      u-boot
arm-linux-gnueabihf-ld.bfd: common/console.o: in function `flush':
/tmp/u-boot/common/console.c:802: undefined reference to `serial_flush'
arm-linux-gnueabihf-ld.bfd: common/stdio.o: in function `stdio_serial_flush':
/tmp/u-boot/common/stdio.c:93: undefined reference to `serial_flush'
make: *** [Makefile:1782: u-boot] Error 1

And serial_flush() is implemented only in serial-uclass.c (which is
DM_SERIAL code).

So could you try to add this additional guard (into this 4/6 patch)?

diff --git a/include/serial.h b/include/serial.h
index f9009d4046e3..fe01bcfadb9b 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -362,7 +362,7 @@ void serial_setbrg(void);
 void serial_putc(const char ch);
 void serial_putc_raw(const char ch);
 void serial_puts(const char *str);
-#ifdef CONFIG_CONSOLE_FLUSH_SUPPORT
+#if defined(CONFIG_CONSOLE_FLUSH_SUPPORT) && CONFIG_IS_ENABLED(DM_SERIAL)
 void serial_flush(void);
 #else
 static inline void serial_flush(void) {}

ds109 with this change compiles fine on my computer.