The Raspberry Pi Should See Much Better SPI Performance On Linux 5.4+

[phoronix]

Phoronix: The Raspberry Pi Should See Much Better SPI Performance On Linux 5.4+

The SPI (Serial Peripheral Interface) pull requests to the Linux kernel normally don't get us excited, but they do when it comes with word of big performance enhancements. There are several SPI performance improvements this round but exciting us the most is the work done on the Broadcom SPI driver for Raspberry Pi hardware...

http://www.phoronix.com/scan.php?page=news_item&px=Raspberry-Pi-Better-SPI

[Guest]

Considering that flashrom can bring my i7 down to it's knees when flashing, and the same thing applies to rpi, this is big news for anyone who deals with SPI in any way. I'm glad someone is trying to improve this area of the kernel.

[tului]

Raspbian should be on this kernel version about the time the Pi 5 launches

[jaskij]

Considering that flashrom can bring my i7 down to it's knees when flashing, and the same thing applies to rpi, this is big news for anyone who deals with SPI in any way. I'm glad someone is trying to improve this area of the kernel.

I don't agree. I have written my own kernel module for a custom project where I could saturate a 4 MHz SPI using about 15% of a single core on a Pi 3. A single transfer was about 10-15 bytes and it had a lot of handling. The BCM drivers definitely needed some improvement, but there is nothing dramatic about them. Your issue was most likely caused by something else, a lot of people use SPI professionally and it's nigh impossible for that code to be in such a bad state. IIRC the bus code itself was not that much different from I2C bus code.