linux-kernel - Re: [PATCH 2/6] wl1251: Use request_firmware_prefer

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Date:   Wed, 3 May 2017 21:02:20 +0200
From:   Arend Van Spriel <arend.vanspriel@...adcom.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Pavel Machek <pavel@....cz>, Daniel Wagner <wagi@...om.org>,
        Tom Gundersen <teg@...m.no>
Cc:     Pali Rohár <pali.rohar@...il.com>,
        Ming Lei <ming.lei@...onical.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        David Gnedt <david.gnedt@...izone.at>,
        Michal Kazior <michal.kazior@...to.com>,
        Tony Lindgren <tony@...mide.com>,
        Sebastian Reichel <sre@...nel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Takashi Iwai <tiwai@...e.de>,
        David Woodhouse <dwmw2@...radead.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Grazvydas Ignotas <notasas@...il.com>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 2/6] wl1251: Use request_firmware_prefer_user() for
 loading NVS calibration data



On 3-1-2017 18:59, Luis R. Rodriguez wrote:
> On Mon, Dec 26, 2016 at 05:35:59PM +0100, Pavel Machek wrote:
>>
>> Right question is "should we solve it without user-space help"?
>>
>> Answer is no, too. Way too complex. Yes, it would be nice if hardware
>> was designed in such a way that getting calibration data from kernel
>> is easy, and if you design hardware, please design it like that. But
>> N900 is not designed like that and getting the calibration through
>> userspace looks like only reasonable solution.
> 
> Arend seems to have a better alternative in mind possible for other
> devices which *can* probably pull of doing this easily and nicely,
> given the nasty history of the usermode helper crap we should not
> in any way discourage such efforts.
> 
> Arend -- please look at the firmware cache, it not a hash but a hash
> table for an O(1) lookups would be a welcomed change, then it could
> be repurposed for what you describe, I think the only difference is
> you'd perhaps want a custom driver hook to fetch the calibration data
> so the driver does whatever it needs.

Hi Luis,

I let my idea catch dust on the shelf for a while. Actually had a couple
of patches ready, but did get around testing them. So I wanted to rebase
them on your linux-next tree. I bumped into the umh lock thing and was
wondering why direct filesystem access was under that lock as well. In
your tree I noticed a fix for that. The more reason to base my work on
top of your firmware_class changes. Now my question is what is the best
branch to choose, because you have a "few" in that repo to choose from ;-)

Regards,
Arend