SPI for IMX6x with cyclic DMA

SPI for IMX6x with cyclic DMA

[Andrea Tessadri]

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I've just developed and tested cyclic DMA transfer for a SPI device on a
IMX6UL with kernel 4.9.88
I wanted to have a single SPI transfer repeated continuously in order to
feed a DAC for generation of a particular waveform for a medical device,
without interruption and minimal jitter (this is why I though to make the
change at low level, instead of making the protocol driver to pump several
identical messages to SPI subsystem)
I am wondering if this feature could be interesting for other applications
and if it is worth to submit a patch for drivers/spi/spi-imx.c
Thank you in advance

  Andrea

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Re: [meta-freescale] SPI for IMX6x with cyclic DMA

[Andrey Zhizhikin]

On Thu, Aug 13, 2020 at 3:31 PM Andrea Tessadri
<tessadriandrea@gmail.com> wrote:
>
> I've just developed and tested cyclic DMA transfer for a SPI device on a IMX6UL with kernel 4.9.88
> I wanted to have a single SPI transfer repeated continuously in order to feed a DAC for generation of a particular waveform for a medical device, without interruption and minimal jitter (this is why I though to make the change at low level, instead of making the protocol driver to pump several identical messages to SPI subsystem)
> I am wondering if this feature could be interesting for other applications and if it is worth to submit a patch for drivers/spi/spi-imx.c

This is definitely a wrong list for those changes, it should go to
LKML instead. This list is used for discussions regarding Yocto
Project distribution, and I believe you're interested in merging your
changes into Kernel. For that you should post this RFC to LKML.

> Thank you in advance
>
>   Andrea
>
> 



-- 
Regards,
Andrey.

Re: [meta-freescale] SPI for IMX6x with cyclic DMA

[Andrea Tessadri]

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Great, thanks!

Il gio 13 ago 2020, 17:17 Eric Nelson <ericnelsonaz@gmail.com> ha scritto:

> Hi Andrea,
>
> On 8/13/20 7:28 AM, Andrey Zhizhikin wrote:
> > On Thu, Aug 13, 2020 at 3:31 PM Andrea Tessadri
> > <tessadriandrea@gmail.com> wrote:
> >>
> >> I've just developed and tested cyclic DMA transfer for a SPI device on
> a IMX6UL with kernel 4.9.88
>
> Cool!
>
> >> I wanted to have a single SPI transfer repeated continuously in order
> to feed a DAC for generation of a particular waveform for a medical device,
> without interruption and minimal jitter (this is why I though to make the
> change at low level, instead of making the protocol driver to pump several
> identical messages to SPI subsystem)
> >> I am wondering if this feature could be interesting for other
> applications and if it is worth to submit a patch for drivers/spi/spi-imx.c
> >
> > This is definitely a wrong list for those changes, it should go to
> > LKML instead. This list is used for discussions regarding Yocto
> > Project distribution, and I believe you're interested in merging your
> > changes into Kernel. For that you should post this RFC to LKML.
> >
>
> Andrey is right that kernel patches aren't submitted through this list.
>
> Depending on how you've implemented this, the proper mailing list will
> be either or both linux-spi and dmaengine as noted here:
>
> http://vger.kernel.org/vger-lists.html
>
> That said, there are probably more potential users on this list,
> and posting it here might get more feedback than those lists.
>
> And to answer your question about whether it is worth submitting the
> patch set, I'd say "yes". Even if it's not accepted, it might prove
> useful to others.
>
> Regards,
>
>
> Eric
>

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