On 18.05.2022 14:45:33, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   210e04ff768142b96452030c4c2627512b30ad95
> commit: eb79a267c9b3e608e7762a1b221428f37ace3aa3 can: mcp251xfd: rename all remaining occurrence to mcp251xfd
> date:   1 year, 8 months ago
> config: arm-randconfig-c002-20220518 (https://download.01.org/0day-ci/archive/20220518/202205181414.n8QRDe8k-lkp@intel.com/config)
> compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 853fa8ee225edf2d0de94b0dcbd31bea916e825e)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install arm cross compiling tool for clang build
>         # apt-get install binutils-arm-linux-gnueabi
>         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eb79a267c9b3e608e7762a1b221428f37ace3aa3
>         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>         git fetch --no-tags linus master
>         git checkout eb79a267c9b3e608e7762a1b221428f37ace3aa3
>         # save the config file
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
> >> drivers/net/can/spi/mcp251xfd/mcp251xfd.h:481:34: warning: field hw_tx_obj within 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:479:2)' is less aligned than 'struct mcp251xfd_hw_tx_obj_raw' and is usually due to 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:479:2)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
>                    struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>                                                   ^
>    drivers/net/can/spi/mcp251xfd/mcp251xfd.h:485:34: warning: field hw_tx_obj within 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:483:2)' is less aligned than 'struct mcp251xfd_hw_tx_obj_raw' and is usually due to 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:483:2)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
>                    struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>                                                   ^
>    drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c:511:1: warning: unused function 'mcp251xfd_chip_set_mode_nowait' [-Wunused-function]
>    mcp251xfd_chip_set_mode_nowait(const struct mcp251xfd_priv *priv,
>    ^
>    3 warnings generated.
> --
> >> drivers/net/can/spi/mcp251xfd/mcp251xfd.h:481:34: warning: field hw_tx_obj within 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:479:2)' is less aligned than 'struct mcp251xfd_hw_tx_obj_raw' and is usually due to 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:479:2)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
>                    struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>                                                   ^
>    drivers/net/can/spi/mcp251xfd/mcp251xfd.h:485:34: warning: field hw_tx_obj within 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:483:2)' is less aligned than 'struct mcp251xfd_hw_tx_obj_raw' and is usually due to 'struct mcp251xfd_tx_obj_load_buf::(unnamed at drivers/net/can/spi/mcp251xfd/mcp251xfd.h:483:2)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
>                    struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>                                                   ^
>    2 warnings generated.
> 
> 
> vim +481 drivers/net/can/spi/mcp251xfd/mcp251xfd.h
> 
>    477	
>    478	union mcp251xfd_tx_obj_load_buf {
>    479		struct __packed {
>    480			struct mcp251xfd_buf_cmd cmd;
>  > 481			struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>    482		} nocrc;
>    483		struct __packed {
>    484			struct mcp251xfd_buf_cmd_crc cmd;
>    485			struct mcp251xfd_hw_tx_obj_raw hw_tx_obj;
>    486			__be16 crc;
>    487		} crc;
>    488	} ____cacheline_aligned;
>    489

The structure layout is intentional as it describes the hardware
messages on the SPI bus. The functions accessing these structs use
appropriate put_unaligned_*() functions.

How to properly annotate these structs to silence the warnings?

Marc

-- 
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