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When the audio driver selects CONFIG_PXA_SSP on ARCH_MMP as a loadable module, and the PXA SPI driver is built-in, we get a link error in the SPI driver: drivers/spi/spi-pxa2xx.o: In function `pxa2xx_spi_remove': spi-pxa2xx.c:(.text+0x5f0): undefined reference to `pxa_ssp_free' drivers/spi/spi-pxa2xx.o: In function `pxa2xx_spi_probe': spi-pxa2xx.c:(.text+0xeac): undefined reference to `pxa_ssp_request' spi-pxa2xx.c:(.text+0x1468): undefined reference to `pxa_ssp_free' spi-pxa2xx.c:(.text+0x15bc): undefined reference to `pxa_ssp_free' The problem is that the PXA SPI driver only uses 'select SSP' specifically when building it for PXA, but we can also build it for PCI, which is meant for Intel x86 SoCs that use the same SPI block. When the sound driver forces the SSP to be a loadable module, the IS_ENABLED() check in include/linux/pxa2xx_ssp.h triggers but the spi driver can't reference the exported symbols. I had a different approach before, making the PCI case depend on X86, which fixed the problem by avoiding the MMP case. This goes a different route, making the driver select PXA_SSP also on MMP, which has an SSP that none of the boards in mainline Linux use for SPI. There is no harm in always enabling the build on MMP (PCI or not PCI), so I do that too, to document that this hardware is actually available on MMP. Link: https://patchwork.kernel.org/patch/8879921/ Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Mark Brown <broonie@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.