Increase SPI buffer size in Raspbian

Question

I need to send 10 k bytes over SPI in single transfer (yes, because Linux is so realtime, if I send these bytes in two transfers, I do not match the timings of IC).

But maximum size of message in spi_bcm2708 kernel module is 4096 bytes. How do I modify this value (preferably without recompilation of the module)? If I can do with specifying parameter to the module, what parameter and in what file I need to specify?

Thanks in advance.

Answer 1

For some time, the Pi Foundation have compiled the SPI device driver into the kernel. The way to change the buffer size now is to edit the /boot/cmdline.txt file and add:

spidev.bufsiz=<NEEDED BUFFER SIZE>

Answer 2

The solution is to add following lines to /etc/modprobe.d/local.conf:

options spidev bufsiz=<NEEDED BUFFER SIZE>