Layerscape中的主题 Gaps between bytes SPI

Gaps between bytes SPI

jgutierrez — Mon, 04 Nov 2019 12:34:20 GMT

Hello,

I'm using LS1021a micro and when I transfer data from QorIQ, in out signals I get the attached picture (yellow = clk, green = cs)

There is a large gap between bytes and it is not always the same.

I would like to reduce this gap to the minimum possible.

Additional data:

- SPIDEV library.

- C and Python code

- SPI mode 3.

- Clock Tested: 1MHz, 4MHz, 8MHz...

- Kernel 4.14.78.

- Yocto

Thank you in advance.

PD: Attached picture and source code used for test.

Re: Gaps between bytes SPI

Pavel — Wed, 06 Nov 2019 06:50:11 GMT

Use LSDK 1909 for the LS1021a.

See attached file.

This file contains fsl_dspi driver from SDK 2.0-1703 and fro LSDK 1909.

Compare the dspi_next_xfer_dma_submit function in LSDK 1909 and dspi_eoq_write function from SDK 2.0-1703.

Have a great day,
Pavel Chubakov

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Re: Gaps between bytes SPI

jgutierrez — Wed, 06 Nov 2019 09:07:49 GMT

Thank you Pavel.

But for project requirements, we need to use Yocto for our distribution.

And as I understand, the LSDK code is not compatible with Yocto.

A yocto recipe it would be very useful for us.

Do you have any suggestion about that?

Thank you again.

Re: Gaps between bytes SPI

Pavel — Wed, 13 Nov 2019 03:49:45 GMT

NXP offers Yocto Linux BSP SDK 2.7 for the LS1021a:

https://source.codeaurora.org/external/qoriq/qoriq-components/yocto-sdk/about/

I have checked that this SDK uses the same SPI driver as SDK 2.0.

Change this driver as code in LSDK 19.09.

Have a great day,
Pavel Chubakov

Re: Gaps between bytes SPI

jgutierrez — Fri, 15 Nov 2019 08:58:44 GMT

Hello PavelChubakov‌.

I will consider it in case it is possible to use LSDK in our project.

Thank you!