On Fri, 2015-04-17 at 10:55 +0200, Arend van Spriel wrote:
> Resend as it bounced on openwrt-devel list.
> 
> -------- Original Message --------
> Subject: Re: [PATCH 10/10] brcmfmac: Add support for multiple PCIE 
> devices in nvram.
> Date: Fri, 17 Apr 2015 10:50:08 +0200
> From: Arend van Spriel <[email protected]>
> To: Rafał Miłecki <[email protected]>
> CC: Hante Meuleman <[email protected]>, 
> "[email protected]"      <[email protected]>, Kalle 
> Valo <[email protected]>,  mailinglist 
> <[email protected]>, Florian Fainelli   <[email protected]>
> 
> + openwrt-devel list
> 
> On 04/17/15 09:45, Rafał Miłecki wrote:
> > Huh, why dropping linux-wireless (and top posting btw)? Please let
> > everyone follow the discussion :)
> >
> > On 15 April 2015 at 21:20, Hante Meuleman<[email protected]>  wrote:
> >> As I wrote to you in a mail and on the openwrt forum, this patch is indeed 
> >> an attempt to support more complex nvram files. I also wrote, that in 
> >> order to be able to use it, the nvram contents of the device (r8000) needs 
> >> tobe put a specific file. Now for your concerns, we can perhaps add 
> >> something which will read the nvram contents directly from an nvram store. 
> >> But thatis irrelevant to this patch. The parsing is still needed, and all 
> >> we wouldneed to add is something which is reading the nvram contents from 
> >> some other place
> >
> > So it makes me wonder if we need this patch in its current form. I
> > think getting NVRAM directly from the platform is much user friendly.
> > It doesn't require user to install some extra tools for dumping NVRAM
> > and putting it in a specific file. One extra layer less.
> > With that said I think it's hard to review your code for parsing
> > NVRAM. We don't know how it's going to be fetched in the first place.
> 
> You already made that point and we agreed to look for a solution.
> 
> >> though it would have to be put under some kernel config flag as this would 
> >> not be supported in non-router systems. The contents of the nvram would 
> >> however still need to be parsed in exactly the same way as the nvram files 
> >> we read from disk.
> >
> > Again, it's hard to say for me. Are you going to use
> > bcm47xx_nvram_getenv? Are you going to use MTD subsystem? Are you
> > going to develop different solution? When using e.g.
> > bcm47xx_nvram_getenv you won't want all this parsing stuff at all.
> 
> Please look at the usage scenario here. The brcmfmac driver is not
> needing a few key,value pairs. It needs a portion of NVRAM to download
> to the device. The patch provides the functionality to do just that. Get
> the appropriate portion, strip comments and whitespace, and send it to
> the device. Using bcm47xx_nvram_getenv is not a useful api as it would
> mean we need brcmfmac to know which key ids to ask for, reassemble it to
> key=value string and send it to the fullmac device.

Following an "nvram erase" none of the needed <key, value> pairs remain
in nvram. So we probably can't use nvram in a reliable way to create the
wireless configuration.

But there's no information about what the (I guess) device firmware
actually needs.

Is there a list of key value pairs used/needed?
What are there default values?
Are sensible default values used for key value pairs that are not
present in the configuration?

Point is there should be only a few entries needed in a configuration to
alter some specific default values for a sane implementation.

Why use pcie domain and bus number?
What do you get from hard coding things that might change over time with
implementation?

The nvram from a vendor install doesn't use pcie domain and bus number,
it uses "0:", "1:" and "2:" prefixes, and as much as I don't like that
either, it is implementation independent.

Knowing more about what is really needed and how it is handled (for
which there is no information whatsoever that I can find) might help me
understand why the driver doesn't work on my R8000.

Perhaps that's a bit harsh, the driver does work partially.

Extracting each prefixed section and replacing the prefix with <pcie
domain>/<bus>/ doesn't seem to make any difference. The driver still
insists these devices are 2.4Ghz only and barfs at any 5Ghz
configuration.

Ian
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