i.MX ProcessorsのトピックRe: Clock output at the SS switch of ECSPI of i.MX6Solo

Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Fri, 04 Mar 2016 05:55:52 GMT

Dear all,

We connect three devices to ECSPI1 port.

We use fsl-yocto-3.10.53-1 .1.0.

The ECSPI driver remains a default.

When ECSPI1 is switched from SS1(Device2) to SS0(Device1), a clock is output momentarily just before SS0 becomes active.

Why is a clock output?

The field setting of each register is the following

ECSPI1_CONREG

- CHANNEL MODE:1 (all master mode)

- SMC: 0

ECSPI1_CONFIGREG

- SCLK_CTL:1 (stay high)

- DATA CTL:0 (stay high)

- SS_POL:0 (Active Low)

- SS_CTL:1 (Negate Chip Select (SS) signal between SPI bursts)

- SCLK_POL:1 (Active low polarity)

- SCLK_PHA:1 (Phase 1 operation)

May I have advice?

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Wed, 09 Mar 2016 20:59:38 GMT

Hi Yuuki,

I have not seen this behavior before. Are you getting some kind of issue thanks to this glitch?

Can you share the steps to reproduce the problem and modifications you have performed to the BSP.

Best Regards,

Alejandro

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Thu, 10 Mar 2016 04:19:56 GMT

Dear Alejandro-san,

Thank you for your support.

In NXP Linux BSP, GPIO controls an SS signal.

This GPIO (SS signal) does not synchronize with a clock.

An SS signal may be asserted before this glitch occurs.

In this case, unpredictable data is read.

We do not know why glitch of the clock occurs.

We are looking for a method avoiding this glitch.

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Wed, 16 Mar 2016 02:55:30 GMT

Alejandro-san,

Thank you for your support.

Is there any sample code using HW SS function(not GPIO) as the SS signal?

Would you send it if there is it?

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Wed, 16 Mar 2016 18:08:34 GMT

Hi Yuuki,

You can try to enable the native Chip select of the ECSPI module.

Please refer to this How to enable native and gpio cs on ecspi

The changes are performed in the dts file.

Please try that and let me know how it goes.

Best Regards,

Alejandro

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Thu, 17 Mar 2016 11:27:33 GMT

Alejandro-san,

Thank you for your support.

We will confirm these contents.

About glitch in CS-GPIO, we attach our source code.

Would you check it?

If this is no good cord, please point it out.

The SABRE-SD board uses only eCSPI1_SS0.

Therefore we think that it cannot be checked with SABRE-SD board.

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Fri, 25 Mar 2016 02:04:18 GMT

Dear Alejandrolozano-san,

Thank you for your support.

We tried to enable the native Chip select of the ECSPI module.

However, each pin was not changed to the SS signal.

If there is the setting that we overlook, would you tell me?

- IOMUXC_SW_MUX_CTL_PAD_EIM_EB2_B

set value : 0x1(MUX_MODE:ECSPI1_SS0)

actual value : 0x5(MUX_MODE:GPIO2_IO30)

- IOMUXC_SW_MUX_CTL_PAD_KEY_COL2

set value : 0x0(MUX_MODE:ECSPI1_SS1)

actual value : 0x5(MUX_MODE:GPIO4_IO10)

- IOMUXC_SW_MUX_CTL_PAD_KEY_ROW2

set value : 0x0(MUX_MODE:ECSPI1_SS2)

actual value : 0x5(MUX_MODE:GPIO4_IO11)

We set the following in dtsi file.

[Setting in dtsi file]

============================================

&iomuxc {

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_hog_1>;

hog {

pinctrl_hog_1: hoggrp-1 {

fsl,pins = <

MX6QDL_PAD_EIM_EB2__ECSPI1_SS0 0x000170B0 /* out ECSPI1 SS0 */

MX6QDL_PAD_KEY_COL2__ECSPI1_SS1 0x000170B0 /* out ECSPI1 SS1 */

MX6QDL_PAD_KEY_ROW2__ECSPI1_SS2 0x0001A0B0 /* out ECSPI1 SS2 */

============================================

ecspi1 {

pinctrl_ecspi1: ecspi1_grp-1 {

fsl,pins = <

MX6QDL_PAD_EIM_D16__ECSPI1_SCLK 0x0001A0B0

MX6QDL_PAD_EIM_D18__ECSPI1_MOSI 0x0001A0B0

MX6QDL_PAD_EIM_D17__ECSPI1_MISO 0x0001A0B0

MX6QDL_PAD_EIM_EB2__ECSPI1_SS0 0x000170B0

MX6QDL_PAD_KEY_COL2__ECSPI1_SS1 0x000170B0

MX6QDL_PAD_KEY_ROW2__ECSPI1_SS2 0x0001A0B0

};

============================================

&ecspi1 {

fsl,spi-num-chipselects = <3>;

cs-gpios = <0>,<0>,<0>; /* active level select is DON'T-CARE here */

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_ecspi1>;

status = "okay";

============================================

Could you give me some advice?

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Fri, 01 Apr 2016 12:06:36 GMT

Dear Alejandrolozano-san,

We approach this problem by two methods to solve it.

One is a method using native Chip select.
Another is method avoiding a glitch with CS-GPIO.

[For native Chip select]

We cannot set pins correctly.

Please see above comment. "Mar 25, 2016 11:04 AM"

Could you give me some advice?

[For glitch with CS-GPIO]

The glitch timing is random.

And there is the case that glitch width is increased.

In this case, CS becomes active during glitch of the clock.

As a result, eCSPI reads unpredictable value.

Is there the method to make a clock line High forcibly?

Please see waveform of the increased glitch width.

The attached file is ECSPI_glitch_on_clock.xlsx.

Is it effective that a dummy reed is put when SS is switched?

Could you give me some advice?

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

karina_valencia — Fri, 08 Apr 2016 12:21:32 GMT

alejandrolozano please continue with the follow up of this case.

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Fri, 08 Apr 2016 20:48:11 GMT

Hi Yuuki,

From what I have seen in the code I made a mistke, it seems that the SPI driver is expecting the SS pins to be configured as GPIO. I am trying to figure out if the driver itself is the one that modifies the SS line or maybe other process.

Is that gpio used or referenced in other device nodes? If you are able to send a way to reproduce the problem in one of our boards please share it. Have you checked that if you use a different gpio you get the same behavior?

Best Regards,

Alejandro

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Mon, 11 Apr 2016 05:26:17 GMT

Dear Alejandrolozano-san,

Thank you for your support.

> Is that gpio used or referenced in other device nodes?

No.

This pin is not used or referenced in other Device nodes.

> If you are able to send a way to reproduce the problem in one of our boards please share it.

In SABRE board, one device is only connected to SPI port.

Therefore we cannot reproduce a problem with an SABRE board.

> Have you checked that if you use a different gpio you get the same behavior?

We will consider it.

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Mon, 11 Apr 2016 16:57:16 GMT

sabre-ai uses ECSPI1 and SS1 for the SPI NOR. Let me check if I am able to reproduce the error on that board.

I will get back to you as soon as possible.

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Tue, 12 Apr 2016 00:38:19 GMT

Hi Yuuki,

I have tried with the sabre-ai, I know the derivative is different but the ECSPI module is the same and I have not been able to reproduce the error. I just contacted the experts for help. Let me see if I am able to reproduce the error in a bareboard project. That will help to identify if it is a wrong configuration or a silicon problem.

Best Regards,

Alejandro

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Tue, 12 Apr 2016 01:04:37 GMT

Hi,

Can you share the dts and dtsi files and the steps and commands you perform to reproduce the problem?

Best Regards,

/Alejandro

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Wed, 13 Apr 2016 02:41:24 GMT

Dear Alejandro-san,

Thank you for your support.

I attach Dtsi file.

- imx6qdl-iiu.dtsi

Would you check it?

Device1 is RTC

Device2 is SPI-NOR Flash 0

A problem occurs in around two hours by switching SS every 10-20us.

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Mon, 18 Apr 2016 02:58:39 GMT

Dear Alejandro-san,

Sorry for pushing you, how about the situation afterward?

Please advise of your findings.

Best Regards,

Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

yuuki — Tue, 19 Apr 2016 02:04:14 GMT

Dear Alejandro-san,

We have an additional question.

(1)
Does BSP include a cord to use SS of the hardware?

(2)
When SCKL_POL was set, is there the prescribed max time when the setting is reflected to a real waveform?

(3)
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6fd8b8503a0dcf66510314dc054745087ae89f94

There is a patch to add a delay from SCKL_POL setting to XCH bit setting.
Would you tell me the reason why this patch is necessary?

Your prompt reply would be appreciated

Best Regards,
Yuuki

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

karina_valencia — Tue, 19 Apr 2016 13:37:32 GMT

alejandrolozano can you help to continue with the follow up as priority?

Re: Clock output at the SS switch of ECSPI of i.MX6Solo

alejandrolozan1 — Tue, 19 Apr 2016 15:56:43 GMT

Hi Yuuki,

Sorry if this is taking too long, but on my side is difficult to reproduce the error due the lack of the correct hardware.

I have contacted the experts so they can shed some light on this. I will get back to you as soon as I get something useful.

Best Regards,

Alejandro