mcp251xfd on RPi 5.4 downstream

From: Drew Fustini <drew@beagleboard.org>
To: linux-can@vger.kernel.org, Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Josh S <josh@macchina.cc>
Subject: mcp251xfd on RPi 5.4 downstream
Date: Wed, 21 Oct 2020 22:10:21 -0500	[thread overview]
Message-ID: <CAPgEAj5eeN7Q9Hs7ZcrvaNCQJ7uW8kyNs3CPiVfQ=AEX9WeYoQ@mail.gmail.com> (raw)

Hi Marc, thanks for working on mcp251xfd driver that has been pulled into 5.10.

I would like to use it with the official rpi-5.4.y branch [1] which
currently ships on their Raspberry Pi OS image.  The target board is a
Raspberry Pi 4 in 32-bit mode which uses bcm2711_defconfig [2]
according to their instructions [3].

I copied mcp251xfd from 5.10 and got this error when compiling:
===================================================
  AR      drivers/net/can/spi/mcp251xfd/built-in.a
  CC [M]  drivers/net/can/spi/mcp251xfd/mcp251xfd-core.o
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c: In function
‘mcp251xfd_tx_ring_init_tx_obj’:
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c:314:23: error: request
for member ‘value’ in something not a structure or union
  xfer->cs_change_delay.value = 0;
                       ^
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c:315:23: error: request
for member ‘unit’ in something not a structure or union
  xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
                       ^
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c: In function ‘mcp251xfd_probe’:
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c:2862:2: error: implicit
declaration of function ‘can_rx_offload_add_manual’
[-Werror=implicit-function-declaration]
  err = can_rx_offload_add_manual(ndev, &priv->offload,
  ^
cc1: some warnings being treated as errors
make[5]: *** [scripts/Makefile.build:266:
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.o] Error 1
make[4]: *** [scripts/Makefile.build:500: drivers/net/can/spi/mcp251xfd] Error 2
make[3]: *** [scripts/Makefile.build:500: drivers/net/can/spi] Error 2
make[2]: *** [scripts/Makefile.build:500: drivers/net/can] Error 2
make[1]: *** [scripts/Makefile.build:500: drivers/net] Error 2
make: *** [Makefile:1732: drivers] Error 2
===================================================

I believe this is a result of 329f0dac4cad ("spi: make
`cs_change_delay` the first user of the `spi_delay` logic") where
integer values `cs_change_delay` and `cs_change_delay_unit` are
replaced with `struct spi_delay`.

I thought I would ask if you have any advice before I start making
incremental changes to get it to compile under 5.4.

thank you,
drew

[1] https://github.com/raspberrypi/linux/blob/rpi-5.4.y/
[2] https://github.com/raspberrypi/linux/blob/rpi-5.4.y/arch/arm/configs/bcm2711_defconfig
[3] https://www.raspberrypi.org/documentation/linux/kernel/building.md