On 21.06.2021 09:24:31, Fabio Estevam wrote: > > The imx SPI driver has quite some overhead, when it comes to small SPI > > transfers. The mcp251fd driver performs much better with the SPI IP > > cores on the raspi, which have quite good optimized drivers. > > > > Hook up a scope to the SPI's clock and chip select lines of the imx, > > you'll see the time between end of transfer until the chip select is > > inactive is longer than the SPI transfer itself. > > > > I expect most bang for the buck can be archived by adding an IRQ less > > busy polling transfer mode, which kicks in below a certain SPI transfer > > length. > > > > On the mcp251xfd driver side, there is some room for optimization. The > > basic idea is to reduce the number of SPI transfers by combining several > > reads into one transfer. This can be done in some places. > > > > For peak loads in CAN-2.0 mode it would be interesting to make use of > > the remaining RAM for a 2nd FIFO. > > Thanks for your reply. > > I do see some RCU related errors every time the application is launched: [...] > Any ideas how these RCU errors could be fixed? Can you test if https://lore.kernel.org/r/20210621123436.2897023-1-mkl@xxxxxxxxxxxxxx fixes your problem? We still have to check if lockdep complains... regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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