> Hi all, > > I am trying to use a tcan4550 together with a Raspberry PI 3 B. I am using the > tcan4x5x driver from net-next. > I always get the following error during startup. > tcan4x5x spi0.0: Probe failed, err=-22 > tcan4x5x: probe of spi0.0 failed with error -22 > > I realized that this happens because the Raspberry PI does only support 8/9 bit > words. https://elinux.org/index.php?title=RPi_SPI#Supported_bits_per_word > In the driver it is set to 32. > spi->bits_per_word = 32; > > Setting this to 8 does not help of course since the tcan chip expects a multiple of > 32 per spi transaction. > I don't know if this is a Raspberry Pi specific problem or if there are more devices > with this hardware limitation. > > Does anyone have a workaround for that? It seems to be enough to just change the bits_per_word value to 8 > > If this a common issue it might be a good idea to patch the driver. I will check if I > can find proper a way to do so. > > Regards, > Konstantin Now I have another really confusing problem. Anything I write to SPI is written little endian. The tcan chip expects big endian. Anything I read from SPI is treated as little endian but is big endian. Does anyone know why this happens? Is there a flag or something I can set for the SPI device/wire to fix this? Regards, Konstantin
