topic Re: Imx6ul spi clock interval in i.MX Processors

Imx6ul spi clock interval

jieh朱 — Tue, 14 May 2019 10:01:29 GMT

Hello！

I am using imx6ul

The kernel version is linux4.1.15

I configured the device tree and kernel and tested it with Documentation/spi/spidev_test.c

However, I set up an 8-bit transfer. After the clock has finished transmitting the 8-bit byte, there will be a time interval and then the clock will be sent. As shown below, I should modify it there to modify the size of the interval.

Re: Imx6ul spi clock interval

igorpadykov — Wed, 15 May 2019 00:30:41 GMT

Hi jiehuai

I am afraid it is not possible to decrease time interval, as it is caused

by processor internal bus delays. For improving throughput one can increase

BURST_LENGTH parameter in ECSPIx_CONREG register or try with/or without

sdma:

                ecspi1: ecspi@02008000 {..
                   dmas = <&sdma 3 7 1>, <&sdma 4 7 2>;
                   dma-names = "rx", "tx";

imx6ul.dtsi\dts\boot\arm\arch - linux-imx - i.MX Linux kernel

Best regards
igor
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Re: Imx6ul spi clock interval

jieh朱 — Wed, 15 May 2019 03:40:38 GMT

Thank you for your reply
   I use dma transfer or pio transfer, it will have the above problem
   How should ECSPIx_CONREG register be configured?
   I saw it in IMX6ULRM
   Is it possible to configure this register?

How to configure if I can. I didn't find the location of this register in the kernel.
Thank you

Re: Imx6ul spi clock interval

igorpadykov — Wed, 15 May 2019 06:04:22 GMT

linux driver does not use it, so it is in reset state, so seems there is no

way to decrease it more.

Best regards
igor

Re: Imx6ul spi clock interval

jieh朱 — Wed, 15 May 2019 09:55:29 GMT

Thank you for your reply

Can I modify the interval of the spi clock? Or is the interval time cpu design can not be modified?

Re: Imx6ul spi clock interval

dahyunkim — Thu, 25 Jul 2019 01:56:47 GMT

jieh朱‌

Hello,

I had a same problem in imx6qdl and I have to reduce the interval of the spi clock.(actually, I have to get no interval in spi clock)

I am wondering the way can modify the interval of the spi clock.

Is the interval time related in Clock Controller Module?