On Thu, Jun 5, 2014 at 10:05 PM, Takashi Iwai <ti...@suse.de> wrote: > At Thu, 5 Jun 2014 21:59:52 +0800, > Ming Lei wrote: >> >> On Thu, Jun 5, 2014 at 9:47 PM, Takashi Iwai <ti...@suse.de> wrote: >> > At Thu, 5 Jun 2014 21:31:56 +0800, >> > Ming Lei wrote: >> >> >> >> On Thu, Jun 5, 2014 at 8:25 PM, Tom Gundersen <t...@jklm.no> wrote: >> >> > >> >> > On 5 Jun 2014 14:18, "Ming Lei" <ming....@canonical.com> wrote: >> >> >> >> >> >> On Wed, Jun 4, 2014 at 11:48 PM, Takashi Iwai <ti...@suse.de> wrote: >> >> >> > [The patch was originally proposed by Tom Gundersen, and rewritten >> >> >> > afterwards by me; most of changelogs below borrowed from Tom's >> >> >> > original patch -- tiwai] >> >> >> > >> >> >> > Currently (at least) the dell-rbu driver selects >> >> >> > FW_LOADER_USER_HELPER, >> >> >> > which means that distros can't really stop loading firmware through >> >> >> > udev without breaking other users (though some have). >> >> >> > >> >> >> > Ideally we would remove/disable the udev firmware helper in both the >> >> >> > kernel and in udev, but if we were to disable it in udev and not the >> >> >> > kernel, the result would be (seemingly) hung kernels as no one would >> >> >> > be around to cancel firmware requests. >> >> >> > >> >> >> > This patch allows udev firmware loading to be disabled while still >> >> >> > allowing non-udev firmware loading, as done by the dell-rbu driver, >> >> >> > to >> >> >> > continue working. This is achieved by only using the fallback >> >> >> > mechanism when the uevent is suppressed. >> >> >> > >> >> >> > The patch renames the user-selectable Kconfig from >> >> >> > FW_LOADER_USER_HELPER >> >> >> > to FW_LOADER_USER_HELPER_FALLBACK, and the former is reverse-selected >> >> >> > by the latter or the drivers that need userhelper like dell-rbu. >> >> >> > >> >> >> > Also, the "default y" is removed together with this change, since >> >> >> > it's >> >> >> > been deprecated in udev upstream, thus rather better to disable it >> >> >> > nowadays. >> >> >> > >> >> >> > Tested with >> >> >> > FW_LOADER_USER_HELPER=n >> >> >> > LATTICE_ECP3_CONFIG=y >> >> >> > DELL_RBU=y >> >> >> > and udev without the firmware loading support, but I don't have the >> >> >> > hardware to test the lattice/dell drivers, so additional testing >> >> >> > would >> >> >> > be appreciated. >> >> >> > >> >> >> > Reviewed-by: Tom Gundersen <t...@jklm.no> >> >> >> > Cc: Ming Lei <ming....@canonical.com> >> >> >> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> >> >> >> > Cc: Abhay Salunke <abhay_salu...@dell.com> >> >> >> > Cc: Stefan Roese <s...@denx.de> >> >> >> > Cc: Arnd Bergmann <a...@arndb.de> >> >> >> > Cc: Kay Sievers <k...@vrfy.org> >> >> >> > Signed-off-by: Takashi Iwai <ti...@suse.de> >> >> >> > --- >> >> >> > drivers/base/Kconfig | 10 ++++++++-- >> >> >> > drivers/base/firmware_class.c | 15 ++++++++++----- >> >> >> > include/linux/firmware.h | 2 +- >> >> >> > 3 files changed, 19 insertions(+), 8 deletions(-) >> >> >> > >> >> >> > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig >> >> >> > index 8fa8deab6449..d0bb32e4c416 100644 >> >> >> > --- a/drivers/base/Kconfig >> >> >> > +++ b/drivers/base/Kconfig >> >> >> > @@ -144,15 +144,21 @@ config EXTRA_FIRMWARE_DIR >> >> >> > some other directory containing the firmware files. >> >> >> > >> >> >> > config FW_LOADER_USER_HELPER >> >> >> > + bool >> >> >> > + >> >> >> > +config FW_LOADER_USER_HELPER_FALLBACK >> >> >> > bool "Fallback user-helper invocation for firmware loading" >> >> >> > depends on FW_LOADER >> >> >> > - default y >> >> >> > + select FW_LOADER_USER_HELPER >> >> >> > help >> >> >> > This option enables / disables the invocation of >> >> >> > user-helper >> >> >> > (e.g. udev) for loading firmware files as a fallback after >> >> >> > the >> >> >> > direct file loading in kernel fails. The user-mode helper >> >> >> > is >> >> >> > no longer required unless you have a special firmware file >> >> >> > that >> >> >> > - resides in a non-standard path. >> >> >> > + resides in a non-standard path. Moreover, the udev support >> >> >> > has >> >> >> > + been deprecated upstream. >> >> >> > + >> >> >> > + If you are unsure about this, say N here. >> >> >> >> >> >> It may be safer to say Y here for fallback if not sure. >> >> > >> >> > Saying Y here will be actively harmful if the firmware loader is >> >> > disabled in >> >> > udev (which I guess most distros will do as soon as they can), so I >> >> > think we >> >> >> >> If fallback is triggered, it means that the firmware can't be found >> >> in default direct rootfs path, so it is better to continue to look for it >> >> from userspace. >> >> >> >> Also it won't a big problem for hanging the request user context >> >> for some while(60sec at default) if udev is disabled, will it? >> >> >> >> BTW, are you sure most distros will do that in the near future? >> >> >> >> > should advice people to say N unless they really know what they are >> >> > doing >> >> > and that their userspace can cope with it. >> >> >> >> That is why I suggest to say Y if someone isn't sure. >> > >> > For the time being, having default this Y causes more troubles. >> >> I am wondering why default Y may cause more troubles, as we >> know, it has been default Y for long long time. > > More trouble = more bug reports. At least, a handful distros suffer. > I don't know the situation with Ubuntu, though.
Looks recently not see related report, :-) >> It only falls back if the request fw is _not_ found from direct loading, >> so it is reasonable to try to continue to look for it from user space. > Some drivers fall back to different firmware (e.g. different revision > suffix) if the requested file isn't found. So, this happens in > reality. So do you think the fallback is better or worse? For CPU microcode case, maybe it is fine, but for other devices, maybe it is better to get a firmware for working at least. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
