About SATA_CAP Register in i.MX6DQ.

[keitanagashima]

Dear All,

Hello. I have a question about SATA_CAP Register in i.MX6DQ.

Refer to bit:28 SMPS & bit:27 SSS of "53.7.1 HBA Capabilites Register (SATA_CAP)" in IMX6DQRM(Rev.3).

There are below descriptions.

- bit:28 SMPS

"This bit is set by the system firmware/BIOS when the platform supports mechanical presence switch for

hot plug operation."

- bit:27 SSS

"This bit is set by the system firmware/BIOS to indicate platform support for staggered devices' spin-up."

These two bits seems to be possible to write by software.

But, this bits are read only.

Is it possible to write to these bits by software?

Best Regards,

Keita

[igorpadykov]

HI Keita

these are read only bits, describing capabilities of SATA module

which are defined at synthesis level of this DesignWare SATA IP module.

So SMPS describes that there is no dedicated mechanical switch for

sata device presence (it is not impelmented for i.MX6 IP synthesis).

SSS describes that "staggered devices spin-up" is not used for i.MX6

SATA module implementation. Note, staggered devices spin-up is used for

multiple devices power-up, while i.MX6 SATA module connects one SATA device.

Spin-up - Wikipedia, the free encyclopedia

Best regards

igor

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[keitanagashima]

Hi Igor,

Thank you for your reply.

Let me clarify my understanding.

===

It is Read only bit and i.MX6 isn't use the bit.

But, BSP, BIOS and Firmware can use this bit as Read/Write.

===

Is my understanding OK?

Best Regards,

Keita

[igorpadykov]

HI Keita

It is read only bits and nobody can write it:

nor i.MX6, nor BSP or other software

Best regards

igor

[keitanagashima]

Hi Igor,

Thank you for you reply.

If your answer is correct, below descriptions look typo.

====

- bit:28 SMPS

"This bit is set by the system firmware/BIOS when the platform supports mechanical presence switch for

hot plug operation."

- bit:27 SSS

"This bit is set by the system firmware/BIOS to indicate platform support for staggered devices' spin-up."

====

Best Regards,

Keita

[igorpadykov · Accepted solution]

HI Keita

these are not typo, just generic IP module description.

Description says:

"when the platform supports..."

I.MX6 platform does not support these features,

it is not implemented on i.MX6 paltform.

Other platforms (not i.MX6) may have this implemented.

Best regards

igor

[keitanagashima]

Hi Igor,

I found the source code which is writing to the SSS bit in Platform SDK.

Refer to attached file.

Please check to my question again.

Best Regards,

Keita

[igorpadykov]

HI Keita

even these bits are written, they have not

effect on chip because these features are not

implemented in synthesis level.

Best regards

igor

[keitanagashima]

Hi Igor,

Thank you for your quick response.

OK. I got it.

Keita