How to change buffer size for spidev on raspberry pi

Question

I'm trying to transfer image data from a camera to the raspberry pi over SPI using the spidev interface. The maximum buffer size possible is 4096, I need about 200,000. This suggested:

sudo su
cd /sys/module/spidev/parameters
chmod 666 bufsiz
echo 65534 > bufsiz

but every time I execute the last line I get:

root@raspberrypi:/sys/module/spidev/parameters# echo 65534 > bufsiz 
bash: echo: write error: Input/output error

I can see the file contents with:

cat bufsiz

which returns 4096 but I cannot change it. Here are the permissions in case they would be helpful:

-rw-rw-rw- 1 root root 4096 May 28 14:23 bufsiz

any help is appreciated. Thanks!

Answer 1

From this:

add spidev.bufsiz=xxxx to /boot/cmdline.txt and remember to keep everything on one line.