DP83TC812R-Q1: Link quality interrupt function check

Hi Alpha,

For a further debug, we might need to ask you certain questions:

• Can you clarify how does the SoC know the interrupt of link quality?
• Are you able to measure the voltage on INT pin when the interrupt event occur?
• Could you also read the register 0x0012 when the interrupt event occur?

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Thank you,

Hillman Lin

hi Hillman，

question 1：Can you clarify how does the SoC know the interrupt of link quality?

answer：The driver interrupt handler calls are very fast and are not rx/tx interrupts，Read phy reg 0x12 as 0x8000 using phytool。The image is the registration interrupt code

question 2：Are you able to measure the voltage on INT pin when the interrupt event occur?

answer：Oscilloscope test is high level

question 3：Could you also read the register 0x0012 when the interrupt event occur?

answer：The 0x12 register can be read

The interrupt schematic is shown below

Hi Cheng,

From the register read, we did not see any link quality interrupt occur. The interrupt pin is pulled high during the interrupt event happen that also indicate DP83TC812 PHY is not getting interrupt.

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Regards,

Hillman Lin

hi Hillman,

The value of register 0x11 is 0x10b, representation: Steady state (normal operation) without an interrupt is logical 1;during interrupt, pin is logical 0

When the low 8 bit of register 0x12 is 0x00, the oscilloscope measures high level, However, when the low 8 bit of register 0x12 is 0x80 (link_qual_int_en), the oscilloscope measures it as low, indicating that there is indeed an interrupt

Thank you,

Xin Cheng

Hi, Hillman:

Can you help to advise if the link_qual_int need to enabled in normal operation? I didn't find description in datasheet.

And what signal 812 to monitor for link quality? 

Hi Cheng and Han,

May I ask couple questions for further debug:

• When you are reading 0x871 for SQI value, did you read it right after the power up process?
• Could you re-read the 0x871 value multiple time after a hard reset to see rather the SQI value become worse?
• Could you read 0x871 multiple times for 10 seconds after the power process to see rather SQI value are stable?

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Thank you,

Hillman Lin

Hi, Hillman:

When you are reading 0x871 for SQI value, did you read it right after the power up process?
answer: yes

Could you re-read the 0x871 value multiple time after a hard reset to see rather the SQI value become worse?
answer: After hard resetting the phy via the RESET pin, the value 0x871 is immediately read 30 times, all 0xee. A total of 5 tests

Could you read 0x871 multiple times for 10 seconds after the power process to see rather SQI value are stable?
answer: Immediately after a cold restart, the 0x871 register value is read 30 times, all 0xee. A total of 5 tests

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Thank you,

Xin Cheng

Hi Cheng,

From the register read, it seems your SQI value is not 7 that you mention in the beginning.

• Did you use extended register to read the SQI value?
• How did you read your SQI value before?
• How long did you wait after the power up or reset when you read 7 on SQI?

It seems the SQI is always maximum. Is your PHY linked up when you read the SQI value?

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Regards,

Hillman Lin

Hi, Hillman:

Did you use extended register to read the SQI value?
answer: yes

How did you read your SQI value before?
answer:The method is as follows
phytool write eth0/0/0x0d 0x1f
phytool write eth0/0/0x0e 0x871
phytool write eth0/0/0x0d 0x401f
phytool read eth0/0/0x0e

How long did you wait after the power up or reset when you read 7 on SQI?
answer:
1、set RESET pin low level
2、set RESET pin high level
3、Immediate read sqi value is 0xee, and it is 0xee all the time

It seems the SQI is always maximum. Is your PHY linked up when you read the SQI value?

yes, phy link down sqi is 0x0, phy link up sqi is 0xee. The system block diagram is as follows, Car Ethernet to RJ45 is always powered, Car Ethernet RJ45 After powering off and then powering on the device, sqi is read as 0xee.

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Regards,

Xin Cheng

Hi Cheng,

You are correct on SQI is always at 7 even after reset. we are currently looking at this link quality interrupt issue internally within the team. 

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Regards,

Hillman Lin

Hi, Hillman:

Thank you for your answer， Looking forward to your reply

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Regards,

Xin Cheng

Hi Cheng,

Thank you for your patient, we will get back to you by the end of this week.

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Regards,

Hillman Lin

Hi Cheng,

Are you able to read register 0x0003 for the 812 that you are using?

Meanwhile, we are still discussing internally on the issue. Thank you for your patience

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Thank you,

Hillman Lin

Hi, Hillman:

register 0x0003 value is 0xa271

Regards,

Xin Cheng

Hi Cheng,

Thank you for the info, we can discuss this through email.

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Regards,

Hillman Lin

Hi, Hillman:

Thank you for your reply, My email is xin.cheng@zongmutech.com.

What's your email address? Would you like me to send an email describing the problem?

Regards,

Xin Cheng

Hi Cheng,

I will contact you through the email. I talk will also loop in Alpha Han in the email chain.

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Regards,

Hillman Lin