[DM368][IPNC][U-Boot] Porting U-boot to DM368-IPNC (1) Ethernet

[Prologue]
Appro's DM368 IPNC reference code uses u-boot version 1.3.4, which is kind of old version without USB and MMC boot support. Appro doesn't seems to upgrade it in the near future (actually it doesn't care except you are big customer). 


Couple days ago I found TI released a new dvsdk for DM365/DM368 (DVSDK_4.02 4_02_00_06), which contains U-Boot 2010.12-rc2. Even though it's not the latest version, it includes all required feature I want. I decided to port this version to DM368-IPNC.




[Main]
After scanning related config files, I decided to use include/configs/davinci_dm365evm.h as template to start the work. This article focuses on enabling Ethernet of U-Boot on IPNC. Others issues will be discussed later.

Steps:
1. create a new config file include/configs/davinci_dm368_ipnc.h with the same content of davinci_dm365evm.h

2. add board information to boards.cfg
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(davinci_dm368_ipnc           arm         arm926ejs   dm365evm            davinci        davinci)

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3. make u-boot!
I didn't use CodeSourcery so had to assign cross compiler.
the commands are
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make CROSS_COMPILE=arm_v5t_le- distclean
make CROSS_COMPILE=arm_v5t_le- clean
make CROSS_COMPILE=arm_v5t_le- davinci_dm368_ipnc_config
make CROSS_COMPILE=arm_v5t_le-

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4. found Ethernet doesn't work. after issuing "ping 192.168.1.1", which is my tftp/nfs server, IPNC hung forever without any message shown. I cannot break it by Ctrl-C either.

5.turn on Ethernet debug to get more messages
at drivers/net/davinci_emac.c, enable emac_dbg
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unsigned int emac_dbg = 1;

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6. reboot IPNC, and issue ping again, I got

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+ emac_close
+ emac_ch_teardown
- emac_ch_teardown
+ emac_ch_teardown
- emac_ch_teardown
- emac_close
+ emac_open

==============================
and IPNC hung. "+ emac_open" was printed by davinci_eth_open()@drivers/net/davinci_emac.c. after get_link_speed statement, it broke by "return 0".
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(!phy.get_link_speed(active_phy_addr))
return(0);

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6. the suspicious point was the variable "active_phy_addr" above. so I added two debug print to ensure it's the root cause.
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debug_emac("+ emac get_link_speed, active_phy_addr = %x\n", active_phy_addr);
if (!phy.get_link_speed(active_phy_addr))
return(0);
debug_emac("- emac get_link_speed\n");

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it confirmed the problem point and active_phy_addr = 0xFF, which is strange.

7. trace code to locate where we got the active_phy_addr and found davinci_eth_phy_detect() @ drivers/net/davinci_emac.c
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phy_act_state = readl(&adap_mdio->ALIVE) & EMAC_MDIO_PHY_MASK;
if (phy_act_state == 0)
return(0); /* No active PHYs */

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there is no error handling code if return 0 (No active PHYs). EMAC_MDIO_PHY_MASK is a macro from EMAC_MDIO_PHY_NUM(@emac_defs.h), which is defined in config file with the value 2.

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/* PHY mask - set only those phy number bits where phy is/can be connected */
#define EMAC_MDIO_PHY_NUM           CONFIG_EMAC_MDIO_PHY_NUM
#define EMAC_MDIO_PHY_MASK          (1 << EMAC_MDIO_PHY_NUM)

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8. Check with schematic file of IPNC and the datasheet of PHY (DM9161), the strapping config is 1 (PHYAD0 pull high), which means the PHY address is 1. Tried to dump the register of MDIO-ALIVE(0x01d0b00c) and the value is 0x00000002. it showed the PHY address should be 1.

9. Change the config value of PHY number at davinci_dm368_ipnc

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 #define CONFIG_EMAC_MDIO_PHY_NUM 1

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and make u-boot again

10. Bingo!

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Ethernet PHY: GENERIC @ 0x01

DaVinci-EMAC

Hit any key to stop autoboot:  0

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[Epilogue]

Some of the issues are not discussed, some are not fixed yet.
To Be Post -
UART
NAND - ECC

To Be Fixed -
USB
MMC
MTD