QorIQ EMI_MDIO controller ACK bit checking

[fdm]

Hi,

Does Ethernet Management Interface controller in QorIQ processors (namely LS1021A and T1040) check the low level on the MDIO line during the second turnaround bit (ACK) for read transactions? What if an external PHY won't set this bit low? Will the read transaction be aborted by controller or it will be completed as normal?

BR,
   Denis

[bpe · Accepted solution]

Devices with eTSEC always go ahead and return what they get from the
line, regardless of TA. DPAA-enabled devices have a means to report
that the PHY didn't respond and data is not valid, see the description
of MDIO_CFG[MDIO_RD_ER] bit in your processor DPAARM.

Note that you cannot rely on u-Boot mdio read command output because
u-Boot     MDIO read procedures don't report errors, see memac_mdio_read() in
memac_phy.c and tsec_local_mdio_read() in fsl_mdio.c

LS1043A is a special case. It does implement MDIO_CFG[MDIO_RD_ER],
but it is affected by erratum A-007900. Refer to the errata list
for details.

Have a great day,
Platon

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[cyrilstrejc]

Hi Platon,

unfortunately I can't find the A-007900 erratum, neither at the LS1043A's Document page: QorIQ® Layerscape 1043A|NXP, nor by google.

Basically, I understand DPAA-enabled devices return what they get from the line plus (in case of Clause 22) true/false information in MDIO[MDIO_RD_ER] register if correct TA by PHY has been provided, correct?

Regarding the A-007900, can You, please, give me an advice how to obtain it or can You share the information about LS1043A's exception from the rule through the forum?

--- UPDATE ---

Following the forum threadhttps://community.nxp.com/message/845707 I assume, to acquire LS1043A's errata, I have to create Service Request or contact our local NXP dealer.

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Thanks,

Cyril

[cyrilstrejc]

Hi Denis,

do You have any progress regarding the QorIQ (LS1043A in my case) MDIO ACK checking? If so, please let me know.

Thanks.

[fdm]

Hi Cyril,

I still have no info regarding LS1 family.

As for T1040, I have confirmed experimentally that it doesn't check the ACK bit during read transactions at least for clause 22 PHY. I have used the "mii read" command in U-Boot; it returns a correct result with no regard to the ACK bit state set by PHY. I have not checked clause 45 PHY read ("mdio read" command).

• Question for NXP:
  

Would you at least confirm the similarity of the EMI_MDIO controllers implemented in the T1 and LS1 families?

BR,
   Denis