linux-kernel - Re: wl1251: NVS firmware data

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Date:	Mon, 8 Dec 2014 18:11:46 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	Ming Lei <ming.lei@...onical.com>, Pavel Machek <pavel@....cz>,
	"John W. Linville" <linville@...driver.com>,
	Grazvydas Ignotas <notasas@...il.com>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	Aaro Koskinen <aaro.koskinen@....fi>,
	Kalle Valo <kvalo@...rom.com>,
	Sebastian Reichel <sre@...g0.de>,
	David Gnedt <david.gnedt@...izone.at>
Subject: Re: wl1251: NVS firmware data

On Monday 08 December 2014 18:05:37 Marcel Holtmann wrote:
> Hi Pali,
> 
> >>>> On Saturday 06 December 2014 13:49:54 Pavel Machek wrote:
> >>>> /**
> >>>> 
> >>>> + * request_firmware_prefer_user: - prefer usermode
> >>>> helper for loading firmware + * @firmware_p: pointer to
> >>>> firmware image
> >>>> + * @name: name of firmware file
> >>>> + * @device: device for which firmware is being loaded
> >>>> + *
> >>>> + * This function works pretty much like
> >>>> request_firmware(), but it prefer + * usermode helper. If
> >>>> usermode helper fails then it fallback to direct access.
> >>>> + * Usefull for dynamic or model specific firmware data.
> >>>> + **/
> >>>> +int request_firmware_prefer_user(const struct firmware
> >>>> **firmware_p, +                           const char
> >>>> *name, struct device *device) +{
> >>>> +       int ret;
> >>>> +       __module_get(THIS_MODULE);
> >>>> +       ret = _request_firmware(firmware_p, name, device,
> >>>> +                               FW_OPT_UEVENT |
> >>>> FW_OPT_PREFER_USER); +       module_put(THIS_MODULE);
> >>>> +       return ret;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(request_firmware_prefer_user);
> >>> 
> >>> I'd like to introduce request_firmware_user() which only
> >>> requests firmware from user space, and this way is simpler
> >>> and more flexible since we have request_firmware_direct()
> >>> already.
> >> 
> >> Why would a driver care about what program provides the
> >> firmware?  It shouldn't at all, and we want to get rid of
> >> the userspace firmware loader, not encourage drivers to
> >> use it "exclusively" at all.
> > 
> > Do not remove it! Without userspace firmware loader it is
> > impossible to load dynamic firmware files.
> 
> why is this dynamic in the first place. It does not sound like
> dynamic data to me at all. This is like the WiFi MAC
> address(es) or Bluetooth BD_ADDR. They are all static
> information. The only difference is that they are on the host
> accessibly filesystem or storage and not on the device
> itself.
> 
> To be honest, for Bluetooth we solved this now. If the device
> is missing key information like the calibration data or
> BD_ADDR, then it comes up unconfigured. A userspace process
> can then go and load the right data into it and then the
> device becomes available as Bluetooth device.
> 
> Trying to use request_firmware to load some random data and
> insist on going through userspace helper for that sounds
> crazy to me. Especially since we are trying hard to get away
> from the userspace loader. Forcing to keep it for new stuff
> sounds backwards to me.
> 
> With the special Nokia partition in mind, why hasn't this been
> turned into a mountable filesystem or into a driver/subsystem
> that can access the data direct from the kernel. I advocated
> for this some time ago. Maybe there should be a special
> subsystem for access to these factory persistent information
> that drivers then just can access. I seem to remember that
> some systems provide these via ACPI. Why does the ARM
> platform has to be special here?
> 
> And the problem of getting Ethernet and WiFi MAC address and
> Bluetooth BD_ADDR comes up many many times. Why not have
> something generic here. And don't tell me request_firmware is
> that generic solution ;)
> 
> Regards
> 
> Marcel

Hi Marcel. I think you did not understand this problem. This 
discussion is not about mac address. Please read email thread 
again and if there are some unclear pars, then ask. Thanks!

-- 
Pali Rohár
pali.rohar@...il.com

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