linux-kernel - Re: patch "firmware loader: allow disabling of udev as firmware loader" added to driver-core tree

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Date:	Thu, 07 Aug 2014 09:57:21 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Shuah Khan <shuahkhan@...il.com>
Cc:	Jean-Michel Hautbois <jhautbois@...il.com>, B_B_Singh@...l.com,
	Greg KH <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>, Kay Sievers <kay@...y.org>,
	Ming Lei <ming.lei@...onical.com>, Stefan Roese <sr@...x.de>,
	Tom Gundersen <teg@...m.no>, Stuart_Hayes@...l.com,
	Srinivas_G_Gowda@...l.com,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: patch "firmware loader: allow disabling of udev as firmware loader" added to driver-core tree

At Wed, 6 Aug 2014 13:00:24 -0600,
Shuah Khan wrote:
> 
> On Wed, Aug 6, 2014 at 3:44 AM, Jean-Michel Hautbois
> <jhautbois@...il.com> wrote:
> > 2014-08-06 11:24 GMT+02:00 Takashi Iwai <tiwai@...e.de>:
> >> At Wed, 6 Aug 2014 11:10:27 +0200,
> >> Jean-Michel Hautbois wrote:
> >>>
> >>> 2014-08-05 21:22 GMT+02:00 Shuah Khan <shuahkhan@...il.com>:
> >>> > On Tue, Aug 5, 2014 at 10:01 AM, Takashi Iwai <tiwai@...e.de> wrote:
> >>> >>> Yes, it worked, if the firmware was in the /lib/firmware directory.
> >>> >>
> >>> >
> >>> > ok it works when the firmware is in /lib/firmware. It sounds to me the
> >>> > reason load fails when the firmware is under /sys/class/firmware is
> >>> > fw_load_from_user_helper() returns -ENOENT when
> >>> > CONFIG_FW_LOADER_USER_HELPER is disabled.
> >>> >
> >>> > It would be nice to see the entire dmesg with debug enabled though.
> >>> >
> >>> > -- Shuah
> >>>
> >>> It does not work with the 3.16 kernel even when firmware is in
> >>> /lib/firmware, it worked before this patch is applied.
> >>
> >> Hm?  3.16 doesn't contain my patch yet.  It's merged for 3.17-rc1.
> >
> > Oh, you are right of course, I am on upstream kernel and I have your
> > patch. I don't mean your match is causing the issue though ;-).
> >
> 
> I think this is what is going on and this patch is the cause:
> fw_load_from_user_helper() is a stub that returns -ENOENT with this
> patch.

... unless specifying the new Kconfig
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.  This is exactly the purpose
of the commit.

> As a result, in _request_firmware() after fw_get_filesystem_firmware()
> fails to find the file, fw_load_from_user_helper() gets called and it
> returns right
> away with -ENOENT.
> 
> In some cases if rootfs mount is in progress, fw_load_from_user_helper()
> steps into load the firmware.

When a module in initrd requires a firmware, it should be put in
initrd, too.


thanks,

Takashi
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