Hi Radu, I love your patch! Perhaps something to improve: [auto build test WARNING on ljones-mfd/for-mfd-next] [also build test WARNING on v4.19-rc1 next-20180831] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Radu-Pirea/Driver-for-at91-usart-in-spi-mode/20180901-165150 base: https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next reproduce: # apt-get install sparse make ARCH=x86_64 allmodconfig make C=1 CF=-D__CHECK_ENDIAN__ sparse warnings: (new ones prefixed by >>) >> drivers/spi/spi-at91-usart.c:218:5: sparse: symbol 'at91_usart_spi_transfer_one' was not declared. Should it be static? >> drivers/spi/spi-at91-usart.c:245:5: sparse: symbol 'at91_usart_spi_prepare_message' was not declared. Should it be static? >> drivers/spi/spi-at91-usart.c:259:5: sparse: symbol 'at91_usart_spi_unprepare_message' was not declared. Should it be static? Please review and possibly fold the followup patch. --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation