About RGMII mode setting of MAC0

[Andrew Jeffery]

Hi Harley

On Sat, 18 Apr 2020, at 20:44, zhouyuanqing8 at outlook.com wrote:
>  
>  Hi, 
> 
>  My name is Harley, I am currently developing an openbmc project based 
> on the AST2500 chip. There are a few questions that need to be 
> consulted. Please help me to answer them. Thank you very much!
> 
>  1、About RGMII mode setting of MAC0
>  The current openbmc project and uboot code support 2 modes: MAC0 uses 
> NCSI, MAC2 uses RGMII, but my board uses MAC0 RGMII. How can I simply 
> configure this to complete this work, or do I have to modify 
> aspeednic.c and add the new patch file under the directory 
> meta-phosphor/aspeed-layer/recipes-bsp/u-boot/files ?

The way to select NCSI vs PHY is via the u-boot config files. Here are some
examples of different platforms selecting between different configs:

```
$ git grep 'UBOOT_MACHINE =' | head
meta-aspeed/conf/machine/evb-ast2500.conf:UBOOT_MACHINE = "ast_g5_phy_config"
meta-aspeed/conf/machine/evb-ast2600.conf:UBOOT_MACHINE = "ast2600_openbmc_defconfig"
meta-evb/meta-evb-aspeed/meta-evb-ast2500/conf/machine/evb-ast2500.conf:UBOOT_MACHINE = "ast_g5_phy_config"
meta-evb/meta-evb-enclustra/meta-evb-zx3-pm3/conf/machine/evb-zx3-pm3.conf:UBOOT_MACHINE = "zynq_zc702_config"
meta-facebook/meta-tiogapass/conf/machine/tiogapass.conf:UBOOT_MACHINE = "ast_g5_ncsi_config"
meta-facebook/meta-yosemitev2/conf/machine/yosemitev2.conf:UBOOT_MACHINE = "ast_g5_ncsi_config"
```

Essentially, you want to configure your platform (i.e. in ${MACHINE}.conf) with:

```
UBOOT_MACHINE = "ast_g5_phy_config"
```

> 
>  2、There are lot of recipes under  directory meta-phosphor, How does 
> bitbake choose specific recipes? I read the manual of bitbake and the 
> project of openbmc, and I didn't find a way to choose. openbmc has many 
> recipes, we can't use them all。

This is handled by variously by packagegroups, DISTRO_FEATURES,
MACHINE_FEATURES and IMAGE_INSTALL. Additionally if we look at
e.g. meta-ibm/meta-witherspoon/conf/machine/witherspoon.conf, we find:

```
require conf/machine/include/ast2500.inc
require conf/machine/include/obmc-bsp-common.inc
require conf/machine/include/openpower.inc
require conf/machine/include/p9.inc
```

If we drill down through these files we find things like
meta-aspeed/conf/machine/include/aspeed.inc:

MACHINE_EXTRA_RRECOMMENDS += "udev-aspeed-vuart udev-aspeed-mtd-partitions"

So if recommended packages are to be installed, then these two packages
will be installed on ASPEED-based images.

The hierarchy of `require` directives helps build up the set of packages to be
installed in the image via at least the variables I mentioned above.

> 
>  3、There are many common recipes under openbmc / meta-phosphor, is 
> there any documentation about the architecture and detailed 
> implementation principles of each recipe? For example, chassis power 
> control.

Less so documentation of the recipes themselves, but you'll find design
discussions, cheatsheets and guides in the docs repository:

https://github.com/openbmc/docs/

Hope that helps.

Andrew