Re: [PATCH] wifi: wilc1000: change firmware path from 'atmel' to 'microchip/wilc'

[<Ajay.Kathat@microchip.com>]

On 7/5/23 14:03, Jakub Kicinski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Fri, 30 Jun 2023 01:22:31 +0000 Ajay.Kathat@microchip.com wrote:
>> To inline the linux-firmware path with driver, the firmware path is changed
>> from 'atmel' to 'microchip/wilc'. This path change will be submitted to
>> 'linux-firmware' as well.
> 
> How are you going to make this backward compatible?
> Users aren't required to update linux-firmware and kernel at the same
> time.


Thanks for pointing it out.

I think, the changes are not fully compatible for upgrading the kernel
and 'linux-firmware' individually. After the driver changes, the
'linux-firmware' upgrade is necessary.

The kernel and 'linux-firmware' can be upgraded independently, so two
combinations are possible for the upgrade.

updated driver : uses modified path(microchip/wilc) to load FW.
updated 'linux-firmware': FW file is at modified path(microchip/wilc)

1. updated driver + old 'linux-firmware' : incompatible
  - The updated driver will look for FW file in '/microchip/wilc' path
which is not present in older 'linux-firmware'. Though the interface
format is compatible, the driver will fail to load it because the file
is not present.


2. old driver + updated 'linux-firmware': compatible
  - A link is created from new path to old FW path so the old driver
should be able to load from linked path.

In order to address scenario#1, a fallback method that loads the FW from
the older path(/atmel) can be added in the driver. I think that change
will make it compatible for scenario#1.
Please suggest, if there is a generic/recommended approach to handle
backward compatibility for FW path change.

Regards,
Ajay