From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Fabio Estevam <festevam@gmail.com>
Cc: linux-can@vger.kernel.org,
Oliver Hartkopp <socketcan@hartkopp.net>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: Re: Testing two MCP2518FD's on i.MX8MM
Date: Mon, 21 Jun 2021 14:37:04 +0200 [thread overview]
Message-ID: <20210621123704.yc7ohwbuedofoq53@pengutronix.de> (raw)
In-Reply-To: <CAOMZO5AMP537Qz1MAb-D_27C=WH-5Cf602hichxty95A6db9-A@mail.gmail.com>
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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@pengutronix.de
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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next prev parent reply other threads:[~2021-06-21 12:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAOMZO5CwS-cO3W148YHVYFwcL3QC8oFJfeQBb+WN=QgEPU7AsQ@mail.gmail.com>
2021-06-12 15:10 ` Testing two MCP2518FD's on i.MX8MM Fabio Estevam
2021-06-15 7:15 ` Marc Kleine-Budde
2021-06-21 12:24 ` Fabio Estevam
2021-06-21 12:37 ` Marc Kleine-Budde [this message]
2021-06-21 13:07 ` Fabio Estevam
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