Re: [PATCH 0/1] add support for enum module parameters

Re: [PATCH 0/1] add support for enum module parameters

[Kalle Valo]

+ linux-wireless, netdev

Jani Nikula <jani.nikula@intel.com> writes:

> On Thu, 14 Apr 2022, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
>> On Thu, Apr 14, 2022 at 03:30:32PM +0300, Jani Nikula wrote:
>>> Hey, I've sent this before, ages ago, but haven't really followed
>>> through with it. I still think it would be useful for many scenarios
>>> where a plain number is a clumsy interface for a module param.
>>> 
>>> Thoughts?
>>
>> We should not be adding new module parameters anyway (they operate on
>> code, not data/devices), so what would this be used for?
>
> I think it's just easier to use names than random values, and this also
> gives you range check on the input.
>
> I also keep telling people not to add new module parameters, but it's
> not like they're going away anytime soon.
>
> If there's a solution to being able to pass device specific debug
> parameters at probe time, I'm all ears. At least i915 has a bunch of
> things which can't really be changed after probe, when debugfs for the
> device is around. Module parameters aren't ideal, but debugfs doesn't
> work for this.

Wireless drivers would also desperately need to pass device specific
parameters at (or before) probe time. And not only debug parameters but
also configuration parameters, for example firmware memory allocations
schemes (optimise for features vs number of clients etc) and whatnot.

Any ideas how to implement that? Is there any prior work for anything
like this? This is pretty hard limiting usability of upstream wireless
drivers and I really want to find a proper solution.


-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH 0/1] add support for enum module parameters

[Greg Kroah-Hartman]

On Wed, Apr 20, 2022 at 08:13:47AM +0300, Kalle Valo wrote:
> + linux-wireless, netdev
> 
> Jani Nikula <jani.nikula@intel.com> writes:
> 
> > On Thu, 14 Apr 2022, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> >> On Thu, Apr 14, 2022 at 03:30:32PM +0300, Jani Nikula wrote:
> >>> Hey, I've sent this before, ages ago, but haven't really followed
> >>> through with it. I still think it would be useful for many scenarios
> >>> where a plain number is a clumsy interface for a module param.
> >>> 
> >>> Thoughts?
> >>
> >> We should not be adding new module parameters anyway (they operate on
> >> code, not data/devices), so what would this be used for?
> >
> > I think it's just easier to use names than random values, and this also
> > gives you range check on the input.
> >
> > I also keep telling people not to add new module parameters, but it's
> > not like they're going away anytime soon.
> >
> > If there's a solution to being able to pass device specific debug
> > parameters at probe time, I'm all ears. At least i915 has a bunch of
> > things which can't really be changed after probe, when debugfs for the
> > device is around. Module parameters aren't ideal, but debugfs doesn't
> > work for this.
> 
> Wireless drivers would also desperately need to pass device specific
> parameters at (or before) probe time. And not only debug parameters but
> also configuration parameters, for example firmware memory allocations
> schemes (optimise for features vs number of clients etc) and whatnot.
> 
> Any ideas how to implement that? Is there any prior work for anything
> like this? This is pretty hard limiting usability of upstream wireless
> drivers and I really want to find a proper solution.

Again, configfs?  That should be what that subsystem was designed for...

thanks,

greg k-h

Re: [PATCH 0/1] add support for enum module parameters

[Ben Greear]

On 4/19/22 10:13 PM, Kalle Valo wrote:
> + linux-wireless, netdev
> 
> Jani Nikula <jani.nikula@intel.com> writes:
> 
>> On Thu, 14 Apr 2022, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
>>> On Thu, Apr 14, 2022 at 03:30:32PM +0300, Jani Nikula wrote:
>>>> Hey, I've sent this before, ages ago, but haven't really followed
>>>> through with it. I still think it would be useful for many scenarios
>>>> where a plain number is a clumsy interface for a module param.
>>>>
>>>> Thoughts?
>>>
>>> We should not be adding new module parameters anyway (they operate on
>>> code, not data/devices), so what would this be used for?
>>
>> I think it's just easier to use names than random values, and this also
>> gives you range check on the input.
>>
>> I also keep telling people not to add new module parameters, but it's
>> not like they're going away anytime soon.
>>
>> If there's a solution to being able to pass device specific debug
>> parameters at probe time, I'm all ears. At least i915 has a bunch of
>> things which can't really be changed after probe, when debugfs for the
>> device is around. Module parameters aren't ideal, but debugfs doesn't
>> work for this.
> 
> Wireless drivers would also desperately need to pass device specific
> parameters at (or before) probe time. And not only debug parameters but
> also configuration parameters, for example firmware memory allocations
> schemes (optimise for features vs number of clients etc) and whatnot.
> 
> Any ideas how to implement that? Is there any prior work for anything
> like this? This is pretty hard limiting usability of upstream wireless
> drivers and I really want to find a proper solution.

I used a 'fwcfg' file that is loaded during ath10k initialization, from
same general location as the firmware.  Name is with pci-id or other unique
identifier like board files sometimes are named, and you get per radio
configuration at device load time.  I'm sure I posted a patch on this
some years ago, but I can point you to my current tree if you prefer.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: [PATCH 0/1] add support for enum module parameters

[Jakub Kicinski]

On Wed, 20 Apr 2022 08:13:47 +0300 Kalle Valo wrote:
> Wireless drivers would also desperately need to pass device specific
> parameters at (or before) probe time. And not only debug parameters but
> also configuration parameters, for example firmware memory allocations
> schemes (optimise for features vs number of clients etc) and whatnot.
> 
> Any ideas how to implement that? Is there any prior work for anything
> like this? This is pretty hard limiting usability of upstream wireless
> drivers and I really want to find a proper solution.

In netdev we have devlink which is used for all sort of device
configuration. devlink-resource sounds like what you need,
but it'd have to be extended to support configuration which requires
reload/re-probe. Currently only devlink-params support that but params
were a mistake so don't use that.