[PATCH] dmaengine: fsl-edma: avoid linking both modules

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

Kbuild does not support having a source file compiled multiple times
and linked into distinct modules, or built-in and modular at the
same time. For fs-edma, there are two common components that are
linked into the fsl-edma.ko for Arm and PowerPC, plus the mcf-edma.ko
module on Coldfire. This violates the rule for compile-testing:

scripts/Makefile.build:236: drivers/dma/Makefile: fsl-edma-common.o is added to multiple modules: fsl-edma mcf-edma
scripts/Makefile.build:236: drivers/dma/Makefile: fsl-edma-trace.o is added to multiple modules: fsl-edma mcf-edma

I tried splitting out the common parts into a separate modules, but
that adds back the complexity that a cleanup patch removed, and it
gets harder with the addition of the tracepoints.

As a minimal workaround, address it at the Kconfig level, by disallowing
the broken configurations.

Link: https://lore.kernel.org/lkml/20240110232255.1099757-1-arnd@kernel.org/
Fixes: 66aac8ea0a6c ("dmaengine: fsl-edma: clean up EXPORT_SYMBOL_GPL in fsl-edma-common.c")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/dma/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 965fa49668ff..b3873d01a2ab 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -394,7 +394,7 @@ config LS2X_APB_DMA
 
 config MCF_EDMA
 	tristate "Freescale eDMA engine support, ColdFire mcf5441x SoCs"
-	depends on M5441x || COMPILE_TEST
+	depends on M5441x || (COMPILE_TEST && FSL_EDMA=n)
 	select DMA_ENGINE
 	select DMA_VIRTUAL_CHANNELS
 	help
-- 
2.39.2