On Tuesday, March 28, 2017 10:44:41 AM CEST Alban wrote:

On Mon, 27 Mar 2017 18:11:15 +0200
Christian Lamparter [off-list ref] wrote:

quoted

On Monday, March 13, 2017 10:05:09 PM CEST Alban wrote:

quoted

The current binding only cover PCI devices so extend it for SoC devices.

Most SoC platforms use an MTD partition for the calibration data
instead of an EEPROM. The qca,no-eeprom property was added to allow
loading the EEPROM content using firmware loading. This new binding
replace this hack with NVMEM cells, so we also mark the qca,no-eeprom
property as deprecated in case anyone ever used it.  

Please don't mark "qca,no-eeprom" as deprecated then.
If some devices geniously need to rely on userspace for extracting 
and processing the calibration data, it should be stay a
optional properties.

Deprecated just mean that it shouldn't be used for new devices. 
But as it is not used by any board, misuse the firmware loading API and
firmware loader user helper are deprecated in udev, I find we could also
just drop it.

But LEDE/OpenWRT rely on the firmware loading API more than ever and 
currently there is not a replacement for it. From what I know, Luis 
tried to replace it with his sysdata approach:

<https://lkml.org/lkml/2016/12/16/204>

however, this was disliked by Greg KH and Linus for the following reasons.
<https://lkml.org/lkml/2016/6/16/995>:

|So I absolutely abhor "changes for changes sake".
|
|If the existing code works for existing drivers, let them keep it.
|
|And if a new interface is truly more flexible, then it should be able
|to implement the old interface with no changes, so that drivers
|shouldn't need to be changed/upgraded.
|
|Then, drivers that actually _want_ new features, or that can take
|advantage of new interfaces to actually make things *simpler*, can
|choose to make those changes. But those changes should have real
|advantages.
|[...]


your nvmem approach would need to be as universal and
powerful as the "qca,no-eeprom" + userspace solutions
in order to deprecate it.
 

quoted

For example: A device that can't do easily without "qca,no-eeprom" is
the AVM FRITZ!WLAN Repeater 300E. For this device, the caldata 
is stored in the flash, however for whatever reason the vendor
choose to "reverse" it. (like completely back to front, not byteswapped
or something). So an extra "unreversing step" is required. So, it would
require some sort of a special nvmem-provider-processor as an 
alternative.

Or just handle this special eeprom format in the ath9k driver. I doubt
that this case is so common that it would justify adding a whole new
layer to nvmem.

Well, you'll have to deal with it in nvmem, if you want it to deprecate
"qca,no-eeprom".

I looked into 10-ath9k-eeprom [0] of LEDE's AR71XX target and I noticed
that quite a few devices patch the MACs of the wifi.
If you look at the code for the Airtight C-55 and C-60, Meraki MR18,
Meraki Z1, you'll notice that each one has to add a fixed value (+1,
+2, ...) to the extraced MAC-Address. So how would you replicate this,
with "nvmem-cell-names = address" without some sort of 
nvmem-provider-processor?

Also, there's another usecase of a nvmem-provider-processor. 
For example, one could be convert all the different types of
ascii-macs (Either strings like "00:11:22:33:44:55", 
"00.11.22.33..." or "00112233..." ) to their binary representation.
For AR71XX, this is mostly done by ath79_parse_ascii_mac:

https://github.com/lede-project/source/blob/master/target/linux/ar71xx/files/arch/mips/ath79/dev-eth.c#L1204

and grep lists the following devices:
mach-dgl-5500-a1.c, mach-dhp-1565-a1.c, mach-dir-505-a1.c, mach-dir-615-c1.c
mach-dir-615-i1.c, mach-dir-825-b1.c, mach-dir-825-c1.c, mach-tew-673gru.c
mach-tew-712br.c, mach-tew-732br.c, mach-tew-823dru.c

I did a quick check: All of them use the extracted MACs for ath9k
and/or ethernet.

Note: I think Ralink/MediaTek will have the same issues.

quoted

quoted

 Optional properties:
+- mac-address: See ethernet.txt in the parent directory
+- local-mac-address: See ethernet.txt in the parent directory
[...]
+
+Deprecated properties:
 - qca,no-eeprom: Indicates that there is no physical EEPROM
connected to the ath9k wireless chip (in this case the calibration /
 			EEPROM data will be loaded from userspace
using the kernel firmware loader).
-- mac-address: See ethernet.txt in the parent directory
-- local-mac-address: See ethernet.txt in the parent directory
-  

It sounds like you want to deprecate mac-address and
local-mac-address as well. If so you sould add this to the commit as
well. From my point of view, people mostly flat-out patched the
eeprom-image if they wanted to set the mac-address. However, this was
an extra step, if nvmem does away with it, I'm completely fine with
deprecating these properties.

The produced diff is very misleading because the mac-address properties
get lumped with the other new optional  properties. But if you look
closely it just move qca,no-eeprom to the deprecated section.

Yes ok. This is the case.

Thanks,
Christian

[0] <https://github.com/lede-project/source/blob/master/target/linux/ar71xx/base-files/etc/hotplug.d/firmware/10-ath9k-eeprom#L85>