Re: [PATCH 0/3] drivers: expand usage of request_firmware_direct()
From: Luis R. Rodriguez
Date: Tue Jul 08 2014 - 20:46:11 EST
On Tue, Jul 08, 2014 at 05:24:05PM -0700, Greg KH wrote:
> On Wed, Jul 09, 2014 at 01:52:44AM +0200, Luis R. Rodriguez wrote:
> > On Tue, Jul 08, 2014 at 03:25:36PM -0700, Greg KH wrote:
> > > On Thu, Jun 26, 2014 at 06:18:05PM +0200, Takashi Iwai wrote:
> > > > At Tue, 24 Jun 2014 15:39:40 -0700,
> > > > Luis R. Rodriguez wrote:
> > > > >
> > > > > From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
> > > > >
> > > > > Takashi added request_firmware_direct() via bba3a87e9 through v3.14-rc1
> > > > > which avoids the unnecessary delay introduced by using the udev firmware
> > > > > loader in case the first try failed when loading we know loading "firmware"
> > > > > is optional. The first use case was for microcode update but if drivers are
> > > > > using it for optional configuration updates, custom EEPROMs, and other
> > > > > junk other than firmware that should apply as well as good use cases,
> > > > > specially if the driver already had a first phase in which it loaded
> > > > > the first required firmware. While reviewing one driver I figured it'd
> > > > > be best to try to give formalizing a check with SmPL. This isn't perfect
> > > > > it had 1 false possitive drivers/fmc/fmc-fakedev.c on the entire kernel
> > > > > run but my hope is this can be extended a bit more to build more
> > > > > confidence, and then perhaps stuff it as a coccicheck.
> > > > >
> > > > > I suppose this will not be required once and if we remove
> > > > > CONFIG_FW_LOADER_USER_HELPER. Is that ever going away for good? I know
> > > > > there was a recent attempt to remove the udev loader support but
> > > > > it was unclear if the special alternative helper support would be
> > > > > removed upstream from the kernel.
> > > >
> > > > Actually a few weeks ago I sent a patch to make request_firmware()
> > > > with usermode helper explicitly to be used by some drivers (like
> > > > dell-rbu). I hope Greg took it for 3.17. Once when this patch is in,
> > > > distros can turn off the usermode helper fallback gracefully, so no
> > > > ugly timeout issue shouldn't happen.
> > >
> > > That patch is now merged, so this series should not be needed anymore,
> > > right?
> > Now that it is merged, and another patch I posted which you also merged about
> > printing differences, the main difference between request_firmware() and
> > request_firmware_direct() for distributions that did not enable the fw
> > loader helper is just a printk. That's all. While the difference is minor
> > this series addresses a few drivers that we know have firmware that is
> > optional, so a printk is indeed not really needed as otherwise it can confuse
> > users in terms of expectations. The SmPL grammar for this series could
> > likely be expanded to cover other uses cases but obviously this is not
> > critical and at best best effort. For distributions that stay in the stone age
> > and do not disable the fw loader helper this will speed up boot for a few use
> > cases. This series still applies then.
> > Whether or not its required or optional for firmware to be loaded for a driver
> > is an example small difference in specifications that I expect drivers /
> > subsystems to be able to make, I suspect the differences might grow in the
> > future so I rather keep these requirements well annonated for now. Another
> > example difference I am looking into is whether or not firmware should be
> > digitally signed. While it may be questionable whether or not this is needed
> > for actual firmware that runs on microprocessors some subsystems might want to
> > use this to abandon other udev helpers which simply throw data over, one of
> > which I am looking into replacing is CRDA for the regulatory database. We
> > recently ran into some snags when the internal regdb is used and we use a
> > parser, having the ability to load it directly using request_firmware_direct()
> > with digital signature support as an option would enable us to simplify how the
> > redb is used/parsed on both embedded and non-embedded systems.
> I'm confused, do you want me to review your patches or not?
> If so, care to resend them, they are now purged from my patch queue...
You can ignore these patches and each driver / subsystem maintainer can
merge as they see fit. The p54 patch already went in, the cxgb4 mainainers
and vub300 maintainers should review the patches for those drivers and
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