Hey,
On 15-11-16 11:27, Hans de Goede wrote:
Hi,
On 15-11-16 11:17, Olliver Schinagl wrote:
Hey Hans,
I was hopeing and expecting this :)
As you will be able to tell below, I need to learn a bit more as to why we do things and discuss this proper I guess.
On 15-11-16 10:26, Hans de Goede wrote:
Hi,
On 15-11-16 04:25, Joe Hershberger wrote:
On Tue, Nov 8, 2016 at 9:54 AM, Olliver Schinagl oliver@schinagl.nl wrote:
Currently we inject 5 ethernet addresses into the environment, just in case we may need them. We do this because some boards have no eeprom (programmed) with a proper ethernet address. With the recent addition of reading actual ethernet addresses from the eeprom via the net_op we should not inject environment variables any more.
Signed-off-by: Olliver Schinagl oliver@schinagl.nl
Acked-by: Joe Hershberger joe.hershberger@ni.com
Erm, this patch seems wrong to me: NACK, let me explain:
- It does not do what its commit message says, it only
removes the second step for setting ethernet addresses from the env, but it keeps the existing code to set them AFAICT, it only does it once now.
- "Currently we inject 5 ethernet addresses into the environment",
this is not true, we only inject ethernet addresses into the environment for devices which have an ethernet alias in dt, so maximum 2 for devices with both wired ethernet and wifi
If we want the fdt to do mac things, shouldn't that be done at a higher level? This is not really board specific is it?
We want to put mac addresses into the fdt, and this is done at a higher level, by existing dt code, which looks at ethernet aliases in dt and then for any which are present, checks the corresponding ethaddr env setting and if set, injects that mac address into the dt-node the alias points to.
What is sunxi specific is setting the environment variables based on the SID. The sunxi specific code also checks the aliases, exactly to avoid the "inject 5 ethernet addresses" thing you are describing, as we don't want to inject ethernet addresses for non existent NICs as that may confuse the user.
- The second attempt at setting ethernet addresses in
the environment after loading the kernel dt is necessary because the kernel dt may be newer and contain more ethernet aliases, e.g. the u-boot dt may only contain the nodes + alias for the wired, while the (newer) kernel dt may also contain a dt-node + alias for the wireless
I agree with you here, but I still don't think this should be board specific
Instead of doing this through the environment I guess you could have the u-boot dt code which is injecting the MACs into the dt call some board specific callback when there is no MAC set in the environment, and implement a weak stub for this. Then all the sunxi environment mangling code can go away, and sunxi can simply:
- Try eeprom if present
- Do the current SID based thing
- We cannot solely rely on the ethernet driver to set
mac-addresses, because the ethernet driver may not be enabled while the kernel does have the ethernet driver enabled; and the kernel relies on u-boot to generate fixed mac-addresses based on the SID independent whether or not u-boot has ethernet enabled, this is especially relevant for wifi chips where the kernel also relies on u-boot generated fixed mac-addresses on e.g. the recent orange-pi boards, which come with a realtek rtl8189etv chip which does not have a mac address programmed.
I agree, and I'll fix that in my new patch series proper by making rtl8189etv also read rom hook which IS board specific
The problem is that u-boot may not have a driver for one of the NICs at all, so no place to call the rom hook at all.
Anyways I believe this is solved by my suggestion for making the u-boot dt code which injects the MAC call a board specific callback when no ethaddr is set in the env.
- AFAIK the dt code for passing mac-addresses to the kernel
relies on the environment variables, so even if we get the mac-address from a ROM we should still store it in the environment variable.
The new patch series does that, as the net core layer does that.
What happens is (note code is mangled and might not be 100% accurate, i reduced it the bares):
eth_read_eeprom_hwaddr(dev);first read from the eeprom, which may return all zero's if it is unconfigured/missconfigured or should not be used from the eeprom. if (is_zero_ethaddr(pdata->enetaddr)) if (eth_get_ops(dev)->read_rom_hwaddr) eth_get_ops(dev)->read_rom_hwaddr(dev); if the eeprom failed to produce a mac, we check the read_rom_hwaddr callback, which hooks into the driver. The driver can be overridden by a board (such as sunxi) where the MAC is generated from the SID.
so at this point we may have a hwaddress actually obtained from the hardware, via the eeprom (or some fixed rom even) or from the hardware itself next we allow 'software' overrides. e.g. u-boot env (and i think this is where the fdt method should live as well
eth_getenv_enetaddr_by_index("eth", dev->seq, env_enetaddr); if (!is_zero_ethaddr(env_enetaddr)) { if (!is_zero_ethaddr(pdata->enetaddr) && memcmp(pdata->enetaddr, env_enetaddr, ARP_HLEN)) memcpy(pdata->enetaddr, env_enetaddr, ARP_HLEN);// <snip> we compare the HW addr and the ENV addr. if the env is unset, we use whatever the hardware supplied us with. if the env is set, it overrides the HW addr. I think next would be to check the fdt to override the env?
} else if (is_valid_ethaddr(pdata->enetaddr)) { eth_setenv_enetaddr_by_index("eth", dev->seq, pdata->enetaddr);Finally, we set whatever mac has come from the above probing into the environment (if the address is actually a valid MAC).
Ok, good I just wanted to make sure that that would still happen.
} else if (is_zero_ethaddr(pdata->enetaddr)) {#ifdef CONFIG_NET_RANDOM_ETHADDR net_random_ethaddr(pdata->enetaddr); otherwise (if configured) let u-boot generate it.
So I think here is where the fdt override should live, as it applies to everyone, not just sunxi.
I think you're thinking too much about the case where u-boot has an actual driver for the NIC (and that driver gets initialized, what if it gets skipped to speed up the boot?) and not enough about the case where there is no driver but we still want to use u-boot's board specific MAC generation code to provide a fixed MAC address to the kernel.
In my other e-mail contradiciting myself I just found this somewhat out, and that indeed is another usecase worth thinking about yeah. So I'll need to re-think that part too.
And then thinks come to mind 'if there are 5 address in the eeprom, but only 2 drivers, do the drivers get the first two?' ... I guess there needs to be a general agreement on strange cases as such. How are non-driver devices handled. The dts obviously is one method, but I'm sure board manufactures will hate us for forcing board specific dts. They want to just produce boards en-masse and may be kind enough to supply eeprom or MAC-prom's with fixed mac addresses stored there.
I think this is an architectural based decision which deserves its own thread?
Olliver
Regards,
Hans