DP83867CR: Issue of low bandwidth

Naman Thaker

Part Number: DP83867CR

Hello,

I am using a IMX8MM based custom boards with DP83867 Ethernet PHY. I am observing low bandwidth when the device is configured as client. Please see below report.

##	Cable	Server	Client	Cable Length	Server Speed (Mbps)	Client Speed (Mbps)
1	Straight 1000 Mbps	DP83867	PC	Approx 1 meters	953	940
2		PC	DP83867	Approx 1 meters	~10	~10
3		DP83867	PC	100 meters	936	935
4		PC	DP83867	100 meters	~3	~3
5	Straight 100 Mbps	DP83867	PC	< 1 meter	94.1	94
6	Straight 100 Mbps	PC	DP83867	< 1 meter	93	93
7	Cross Cable 1000 Mbps	DP83867	PC	Approx 1 meters	940	939
8	Cross Cable 1000 Mbps	PC	DP83867	Approx 1 meters	627	627

The PHY is directly connected to the PC through the Ethernet cable and both are configured with static IPs. As seen from the above table, in every case with low bandwidth, the device is configured as client.

I used iperf3 tool to test the bandwidth. The IMX8MM device is running Android 9.0 OS and PC has Ubuntu 16.04 OS.

Please help to improve the Ethernet performance.

Thanks in advance.

over 3 years ago

0 Cecilia Reyes over 3 years ago

TI__Genius 9920 points

Hi Naman,

Are the register settings different when configured as server or client? What other changes are made when switching the configurations?

Thanks,

Cecilia

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

I am not changing any register settings when configuring the device as either server or client. I am only using below iperf3 commands to configure the PC and device as server or client:

Server command: iperf3 -s -i1

Client command: iperf3 -c <SERVER_IP> -i1 -t30

Thanks,

Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman

Can you please share the register dump for when both devices change? I am wondering to see if anything changes on the PHY when this occurs.

Thanks,

Cecilia

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

Below are the register dump with DP83867 acting as server:

REG=0x0, VAL=0x1140
REG=0x1, VAL=0x796d
REG=0x2, VAL=0x2000
REG=0x3, VAL=0xa231
REG=0x4, VAL=0x05e1
REG=0x5, VAL=0xcde1
REG=0x6, VAL=0x006d
REG=0x7, VAL=0x2001
REG=0x8, VAL=0x5006
REG=0x9, VAL=0x0200
REG=0xa, VAL=0x7800
REG=0xb, VAL=0000
REG=0xc, VAL=0000
REG=0xd, VAL=0x401f
REG=0xe, VAL=0x00a8
REG=0xf, VAL=0x3000
REG=0x10, VAL=0x5048
REG=0x11, VAL=0xac02
REG=0x12, VAL=0000
REG=0x13, VAL=0000
REG=0x14, VAL=0x29c7
REG=0x15, VAL=0000
REG=0x16, VAL=0000
REG=0x17, VAL=0x0040
REG=0x18, VAL=0x6150
REG=0x19, VAL=0x4444
REG=0x1a, VAL=0x0002
REG=0x1b, VAL=0000
REG=0x1c, VAL=0000
REG=0x1d, VAL=0000
REG=0x1e, VAL=0x0002
REG=0x1f, VAL=0000
REG=0x20, VAL=0x1140
REG=0x21, VAL=0x796d
REG=0x22, VAL=0x2000
REG=0x23, VAL=0xa231
REG=0x24, VAL=0x05e1
REG=0x25, VAL=0xcde1
REG=0x26, VAL=0x006d
REG=0x27, VAL=0x2001
REG=0x28, VAL=0x5006
REG=0x29, VAL=0x0200
REG=0x2a, VAL=0x7800
REG=0x2b, VAL=0000
REG=0x2c, VAL=0000
REG=0x2d, VAL=0x401f
REG=0x2e, VAL=0x00a8
REG=0x2f, VAL=0x3000
REG=0x30, VAL=0x5048
REG=0x31, VAL=0xac02
REG=0x32, VAL=0000
REG=0x33, VAL=0000
REG=0x34, VAL=0x29c7
REG=0x35, VAL=0000
REG=0x36, VAL=0000
REG=0x37, VAL=0x0040
REG=0x38, VAL=0x6150
REG=0x39, VAL=0x4444
REG=0x3a, VAL=0x0002
REG=0x3b, VAL=0000
REG=0x3c, VAL=0000
REG=0x3d, VAL=0000
REG=0x3e, VAL=0x0002
REG=0x3f, VAL=0000
REG=0x40, VAL=0x1140
REG=0x41, VAL=0x796d
REG=0x42, VAL=0x2000
REG=0x43, VAL=0xa231
REG=0x44, VAL=0x05e1
REG=0x45, VAL=0xcde1
REG=0x46, VAL=0x006d
REG=0x47, VAL=0x2001
REG=0x48, VAL=0x5006
REG=0x49, VAL=0x0200
REG=0x4a, VAL=0x7800
REG=0x4b, VAL=0000
REG=0x4c, VAL=0000
REG=0x4d, VAL=0x401f
REG=0x4e, VAL=0x00a8
REG=0x4f, VAL=0x3000
REG=0x50, VAL=0x5048
REG=0x51, VAL=0xac02
REG=0x52, VAL=0000
REG=0x53, VAL=0000
REG=0x54, VAL=0x29c7
REG=0x55, VAL=0000
REG=0x56, VAL=0000
REG=0x57, VAL=0x0040
REG=0x58, VAL=0x6150
REG=0x59, VAL=0x4444
REG=0x5a, VAL=0x0002
REG=0x5b, VAL=0000
REG=0x5c, VAL=0000
REG=0x5d, VAL=0000
REG=0x5e, VAL=0x0002
REG=0x5f, VAL=0000
REG=0x60, VAL=0x1140
REG=0x61, VAL=0x796d
REG=0x62, VAL=0x2000
REG=0x63, VAL=0xa231
REG=0x64, VAL=0x05e1
REG=0x65, VAL=0xcde1
REG=0x66, VAL=0x006d
REG=0x67, VAL=0x2001
REG=0x68, VAL=0x5006
REG=0x69, VAL=0x0200
REG=0x6a, VAL=0x7800
REG=0x6b, VAL=0000
REG=0x6c, VAL=0000
REG=0x6d, VAL=0x401f
REG=0x6e, VAL=0x00a8
REG=0x6f, VAL=0x3000
REG=0x70, VAL=0x5048
REG=0x71, VAL=0xac02
REG=0x72, VAL=0000
REG=0x73, VAL=0000
REG=0x74, VAL=0x29c7
REG=0x75, VAL=0000
REG=0x76, VAL=0000
REG=0x77, VAL=0x0040
REG=0x78, VAL=0x6150
REG=0x79, VAL=0x4444
REG=0x7a, VAL=0x0002
REG=0x7b, VAL=0000
REG=0x7c, VAL=0000
REG=0x7d, VAL=0000
REG=0x7e, VAL=0x0002
REG=0x7f, VAL=0000
REG=0x80, VAL=0x1140
REG=0x81, VAL=0x796d
REG=0x82, VAL=0x2000
REG=0x83, VAL=0xa231
REG=0x84, VAL=0x05e1
REG=0x85, VAL=0xcde1
REG=0x86, VAL=0x006d
REG=0x87, VAL=0x2001
REG=0x88, VAL=0x5006
REG=0x89, VAL=0x0200
REG=0x8a, VAL=0x7800
REG=0x8b, VAL=0000
REG=0x8c, VAL=0000
REG=0x8d, VAL=0x401f
REG=0x8e, VAL=0x00a8
REG=0x8f, VAL=0x3000
REG=0x90, VAL=0x5048
REG=0x91, VAL=0xac02
REG=0x92, VAL=0000
REG=0x93, VAL=0000
REG=0x94, VAL=0x29c7
REG=0x95, VAL=0000
REG=0x96, VAL=0000
REG=0x97, VAL=0x0040
REG=0x98, VAL=0x6150
REG=0x99, VAL=0x4444
REG=0x9a, VAL=0x0002
REG=0x9b, VAL=0000
REG=0x9c, VAL=0000
REG=0x9d, VAL=0000
REG=0x9e, VAL=0x0002
REG=0x9f, VAL=0000
REG=0xa0, VAL=0x1140
REG=0xa1, VAL=0x796d
REG=0xa2, VAL=0x2000
REG=0xa3, VAL=0xa231
REG=0xa4, VAL=0x05e1
REG=0xa5, VAL=0xcde1
REG=0xa6, VAL=0x006d
REG=0xa7, VAL=0x2001
REG=0xa8, VAL=0x5006
REG=0xa9, VAL=0x0200
REG=0xaa, VAL=0x7800
REG=0xab, VAL=0000
REG=0xac, VAL=0000
REG=0xad, VAL=0x401f
REG=0xae, VAL=0x00a8
REG=0xaf, VAL=0x3000
REG=0xb0, VAL=0x5048
REG=0xb1, VAL=0xac02
REG=0xb2, VAL=0000
REG=0xb3, VAL=0000
REG=0xb4, VAL=0x29c7
REG=0xb5, VAL=0000
REG=0xb6, VAL=0000
REG=0xb7, VAL=0x0040
REG=0xb8, VAL=0x6150
REG=0xb9, VAL=0x4444
REG=0xba, VAL=0x0002
REG=0xbb, VAL=0000
REG=0xbc, VAL=0000
REG=0xbd, VAL=0000
REG=0xbe, VAL=0x0002
REG=0xbf, VAL=0000
REG=0xc0, VAL=0x1140
REG=0xc1, VAL=0x796d
REG=0xc2, VAL=0x2000
REG=0xc3, VAL=0xa231
REG=0xc4, VAL=0x05e1
REG=0xc5, VAL=0xcde1
REG=0xc6, VAL=0x006d
REG=0xc7, VAL=0x2001
REG=0xc8, VAL=0x5006
REG=0xc9, VAL=0x0200
REG=0xca, VAL=0x7800
REG=0xcb, VAL=0000
REG=0xcc, VAL=0000
REG=0xcd, VAL=0x401f
REG=0xce, VAL=0x00a8
REG=0xcf, VAL=0x3000
REG=0xd0, VAL=0x5048
REG=0xd1, VAL=0xac02
REG=0xd2, VAL=0000
REG=0xd3, VAL=0000
REG=0xd4, VAL=0x29c7
REG=0xd5, VAL=0000
REG=0xd6, VAL=0000
REG=0xd7, VAL=0x0040
REG=0xd8, VAL=0x6150
REG=0xd9, VAL=0x4444
REG=0xda, VAL=0x0002
REG=0xdb, VAL=0000
REG=0xdc, VAL=0000
REG=0xdd, VAL=0000
REG=0xde, VAL=0x0002
REG=0xdf, VAL=0000
REG=0xe0, VAL=0x1140
REG=0xe1, VAL=0x796d
REG=0xe2, VAL=0x2000
REG=0xe3, VAL=0xa231
REG=0xe4, VAL=0x05e1
REG=0xe5, VAL=0xcde1
REG=0xe6, VAL=0x006d
REG=0xe7, VAL=0x2001
REG=0xe8, VAL=0x5006
REG=0xe9, VAL=0x0200
REG=0xea, VAL=0x7800
REG=0xeb, VAL=0000
REG=0xec, VAL=0000
REG=0xed, VAL=0x401f
REG=0xee, VAL=0x00a8
REG=0xef, VAL=0x3000
REG=0xf0, VAL=0x5048
REG=0xf1, VAL=0xac02
REG=0xf2, VAL=0000
REG=0xf3, VAL=0000
REG=0xf4, VAL=0x29c7
REG=0xf5, VAL=0000
REG=0xf6, VAL=0000
REG=0xf7, VAL=0x0040
REG=0xf8, VAL=0x6150
REG=0xf9, VAL=0x4444
REG=0xfa, VAL=0x0002
REG=0xfb, VAL=0000
REG=0xfc, VAL=0000
REG=0xfd, VAL=0000
REG=0xfe, VAL=0x0002
REG=0xff, VAL=0000
REG=0x100, VAL=0x1140
REG=0x101, VAL=0x796d
REG=0x102, VAL=0x2000
REG=0x103, VAL=0xa231
REG=0x104, VAL=0x05e1
REG=0x105, VAL=0xcde1
REG=0x106, VAL=0x006d
REG=0x107, VAL=0x2001
REG=0x108, VAL=0x5006
REG=0x109, VAL=0x0200
REG=0x10a, VAL=0x7800
REG=0x10b, VAL=0000
REG=0x10c, VAL=0000
REG=0x10d, VAL=0x401f
REG=0x10e, VAL=0x00a8
REG=0x10f, VAL=0x3000
REG=0x110, VAL=0x5048
REG=0x111, VAL=0xac02
REG=0x112, VAL=0000
REG=0x113, VAL=0000
REG=0x114, VAL=0x29c7
REG=0x115, VAL=0000
REG=0x116, VAL=0000
REG=0x117, VAL=0x0040
REG=0x118, VAL=0x6150
REG=0x119, VAL=0x4444
REG=0x11a, VAL=0x0002
REG=0x11b, VAL=0000
REG=0x11c, VAL=0000
REG=0x11d, VAL=0000
REG=0x11e, VAL=0x0002
REG=0x11f, VAL=0000
REG=0x120, VAL=0x1140
REG=0x121, VAL=0x796d
REG=0x122, VAL=0x2000
REG=0x123, VAL=0xa231
REG=0x124, VAL=0x05e1
REG=0x125, VAL=0xcde1
REG=0x126, VAL=0x006d
REG=0x127, VAL=0x2001
REG=0x128, VAL=0x5006
REG=0x129, VAL=0x0200
REG=0x12a, VAL=0x7800
REG=0x12b, VAL=0000
REG=0x12c, VAL=0000
REG=0x12d, VAL=0x401f
REG=0x12e, VAL=0x00a8
REG=0x12f, VAL=0x3000
REG=0x130, VAL=0x5048
REG=0x131, VAL=0xac02
REG=0x132, VAL=0000
REG=0x133, VAL=0000
REG=0x134, VAL=0x29c7
REG=0x135, VAL=0000
REG=0x136, VAL=0000
REG=0x137, VAL=0x0040
REG=0x138, VAL=0x6150
REG=0x139, VAL=0x4444
REG=0x13a, VAL=0x0002
REG=0x13b, VAL=0000
REG=0x13c, VAL=0000
REG=0x13d, VAL=0000
REG=0x13e, VAL=0x0002
REG=0x13f, VAL=0000
REG=0x140, VAL=0x1140
REG=0x141, VAL=0x796d
REG=0x142, VAL=0x2000
REG=0x143, VAL=0xa231
REG=0x144, VAL=0x05e1
REG=0x145, VAL=0xcde1
REG=0x146, VAL=0x006d
REG=0x147, VAL=0x2001
REG=0x148, VAL=0x5006
REG=0x149, VAL=0x0200
REG=0x14a, VAL=0x7800
REG=0x14b, VAL=0000
REG=0x14c, VAL=0000
REG=0x14d, VAL=0x401f
REG=0x14e, VAL=0x00a8
REG=0x14f, VAL=0x3000
REG=0x150, VAL=0x5048
REG=0x151, VAL=0xac02
REG=0x152, VAL=0000
REG=0x153, VAL=0000
REG=0x154, VAL=0x29c7
REG=0x155, VAL=0000
REG=0x156, VAL=0000
REG=0x157, VAL=0x0040
REG=0x158, VAL=0x6150
REG=0x159, VAL=0x4444
REG=0x15a, VAL=0x0002
REG=0x15b, VAL=0000
REG=0x15c, VAL=0000
REG=0x15d, VAL=0000
REG=0x15e, VAL=0x0002
REG=0x15f, VAL=0000
REG=0x160, VAL=0x1140
REG=0x161, VAL=0x796d
REG=0x162, VAL=0x2000
REG=0x163, VAL=0xa231
REG=0x164, VAL=0x05e1
REG=0x165, VAL=0xcde1
REG=0x166, VAL=0x006d
REG=0x167, VAL=0x2001
REG=0x168, VAL=0x5006
REG=0x169, VAL=0x0200
REG=0x16a, VAL=0x7800
REG=0x16b, VAL=0000
REG=0x16c, VAL=0000
REG=0x16d, VAL=0x401f
REG=0x16e, VAL=0x00a8
REG=0x16f, VAL=0x3000
REG=0x170, VAL=0x5048
REG=0x171, VAL=0xac02
REG=0x172, VAL=0000
REG=0x173, VAL=0000
REG=0x174, VAL=0x29c7
REG=0x175, VAL=0000
REG=0x176, VAL=0000
REG=0x177, VAL=0x0040
REG=0x178, VAL=0x6150
REG=0x179, VAL=0x4444
REG=0x17a, VAL=0x0002
REG=0x17b, VAL=0000
REG=0x17c, VAL=0000
REG=0x17d, VAL=0000
REG=0x17e, VAL=0x0002
REG=0x17f, VAL=0000
REG=0x180, VAL=0x1140
REG=0x181, VAL=0x796d
REG=0x182, VAL=0x2000
REG=0x183, VAL=0xa231
REG=0x184, VAL=0x05e1
REG=0x185, VAL=0xcde1
REG=0x186, VAL=0x006d
REG=0x187, VAL=0x2001
REG=0x188, VAL=0x5006
REG=0x189, VAL=0x0200
REG=0x18a, VAL=0x7800
REG=0x18b, VAL=0000
REG=0x18c, VAL=0000
REG=0x18d, VAL=0x401f
REG=0x18e, VAL=0x00a8
REG=0x18f, VAL=0x3000
REG=0x190, VAL=0x5048
REG=0x191, VAL=0xac02
REG=0x192, VAL=0000
REG=0x193, VAL=0000
REG=0x194, VAL=0x29c7
REG=0x195, VAL=0000
REG=0x196, VAL=0000
REG=0x197, VAL=0x0040
REG=0x198, VAL=0x6150
REG=0x199, VAL=0x4444
REG=0x19a, VAL=0x0002
REG=0x19b, VAL=0000
REG=0x19c, VAL=0000
REG=0x19d, VAL=0000
REG=0x19e, VAL=0x0002
REG=0x19f, VAL=0000
REG=0x1a0, VAL=0x1140
REG=0x1a1, VAL=0x796d
REG=0x1a2, VAL=0x2000
REG=0x1a3, VAL=0xa231
REG=0x1a4, VAL=0x05e1
REG=0x1a5, VAL=0xcde1
REG=0x1a6, VAL=0x006d
REG=0x1a7, VAL=0x2001
REG=0x1a8, VAL=0x5006
REG=0x1a9, VAL=0x0200
REG=0x1aa, VAL=0x7800
REG=0x1ab, VAL=0000
REG=0x1ac, VAL=0000
REG=0x1ad, VAL=0x401f
REG=0x1ae, VAL=0x00a8
REG=0x1af, VAL=0x3000
REG=0x1b0, VAL=0x5048
REG=0x1b1, VAL=0xac02
REG=0x1b2, VAL=0000
REG=0x1b3, VAL=0000
REG=0x1b4, VAL=0x29c7
REG=0x1b5, VAL=0000
REG=0x1b6, VAL=0000
REG=0x1b7, VAL=0x0040
REG=0x1b8, VAL=0x6150
REG=0x1b9, VAL=0x4444
REG=0x1ba, VAL=0x0002
REG=0x1bb, VAL=0000
REG=0x1bc, VAL=0000
REG=0x1bd, VAL=0000
REG=0x1be, VAL=0x0002
REG=0x1bf, VAL=0000
REG=0x1c0, VAL=0x1140
REG=0x1c1, VAL=0x796d
REG=0x1c2, VAL=0x2000
REG=0x1c3, VAL=0xa231
REG=0x1c4, VAL=0x05e1
REG=0x1c5, VAL=0xcde1
REG=0x1c6, VAL=0x006d
REG=0x1c7, VAL=0x2001
REG=0x1c8, VAL=0x5006
REG=0x1c9, VAL=0x0200
REG=0x1ca, VAL=0x7800
REG=0x1cb, VAL=0000
REG=0x1cc, VAL=0000
REG=0x1cd, VAL=0x401f
REG=0x1ce, VAL=0x00a8
REG=0x1cf, VAL=0x3000
REG=0x1d0, VAL=0x5048
REG=0x1d1, VAL=0xac02
REG=0x1d2, VAL=0000
REG=0x1d3, VAL=0000
REG=0x1d4, VAL=0x29c7
REG=0x1d5, VAL=0000

Below are register dump with DP83867 acting as client:

Let me know if anything further is required.

Thanks,

Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman,

I'll need a couple days to review the register dumps and see if there are any clues as to the difference on bandwidth. Thanks for your patience,

Cecilia

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

Let me know when you have any update.

In the meantime, could you confirm if this is purely a SW issue which can be resolved either by register settings or changes in PHY driver?

I am asking this because our HW team needs to confirm that the module for manufacturing the next batch of boards with this PHY. So if the issue is purely SW one, we can go ahead and make the changes in SW release. But if the issue turns out to be HW one, then our next batch will be compromised.

Thanks,

Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman,

It looks like there is no change from the register dump when changing between configurations. So it doesn't look to be any software problems. I'll have to review with my team internally to see if there are any other HW items to debug.

Thanks,

Cecilia

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

Here is some further information from HW side of DP83867 which might help with the debugging.

Below is the schematic of DP83867 section that we have implemented in our system.

The schematic was not reviewed by TI. We followed below checklist which was shared and suggested to us by our TI FAE. The schematic and layout were designed as per this checklist only.

DP83867_Schematic_Design_Review_Checklist (1).xlsx

Regards,

Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman,

What are 4.7pF capacitors used for on the MDI pins?

Thanks for sharing the schematic, would it be possible to share the block diagram of the application as well? When the DP83867 is configured as the client in this scenario, is it receiving packets from the server (PC)?

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

The 4.7pF capacitors are used as per the reference design found in below document which was downloaded from TI website.

Design guidelines for DP83867CRRGZ.pdf

When DP83857 is configured as client, it sends packets to the server. In iperf terminology, the client uploads packets while the server downloads the packets.

Please refer this link for information on iperf tool: openmaniak.com/iperf.php

Regards,

Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman,

Ok, I'll need to review and share my feedback by end of day Thursday.

Thanks

Cecilia

0 Cecilia Reyes over 3 years ago in reply to Cecilia Reyes

TI__Genius 9920 points

Hi Naman,

It seems as though the transmit or receive interface of RGMII is not properly tuned for delay configuration. Could you try configuring the delay settings separately? It can be done through reg 0x86.

Thanks,

Cecilia

0 Naman Thaker over 3 years ago in reply to Cecilia Reyes

Prodigy 210 points

Hi Cecilia,

Changing the TX and RX delay value to 2ns in the register 0x86 worked. Now I am getting ~1Gbps speed during upload and download.

I got this delay value by hit and trial. Is there any document which specifies what this value should be set to?

Is it possible that changing this value will impact the performance when using some different router or switch instead of connecting with PC?
In our final use-case for the device, the PHY can be connected to anything like a off-the-self router or a switch. I want to understand if there could be a case when these timing may hinder the performance. Or will these changes work in every case now?

Regards,
Naman

0 Cecilia Reyes over 3 years ago in reply to Naman Thaker

TI__Genius 9920 points

Hi Naman,

That is good to hear that you have the correct bandwidth. We have an application note on RGMII timing budgets that goes over how to calculate the budgeting needed when using RGMII with the DP83867.

I can't confirm whether all devices will be impacted as I think it will be dependent on the timing on the link partner as well.

Interface

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DP83867CR: Issue of low bandwidth