Mark Brown [Sat, 20 Aug 2011 18:28:59 +0000 (19:28 +0100)]
ASoC: Optimise WM8996 no interrupt path
This occurs frequently if we are in edge triggered mode as we must poll the
interrupt status register until we get no more interrupts so it's worth
the effort - it means we skip writing null acknowledgements to the chip.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
For non-audio uses like accessory detection we can use a lower quality,
unregulated microphone bias, saving a little power. As the hardware can
manually enable and disable the biases we can select regulating mode
automatically with supply widgets connected to the biases.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Axel Lin [Thu, 18 Aug 2011 07:31:04 +0000 (15:31 +0800)]
ASoC: sta32x: Move resource allocation and release to the corresponding callback functions
This patch includes below small fixes:
1. Move sta32x_set_bias_level() from sta32x_i2c_remove() to sta32x_remove().
2. Remove a redundant regulator_bulk_free() call in sta32x_i2c_remove(),
as we will call regulator_bulk_free() in sta32x_remove().
3. Remove unneeded snd_soc_codec_set_drvdata(codec, NULL) in sta32x_i2c_remove.
The i2c core will set the clientdata to NULL.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Johannes Stezenbach <js@sig21.net> Acked-by: Liam Girdwood <lrg@ti.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Jarkko Nikula [Thu, 18 Aug 2011 12:02:47 +0000 (15:02 +0300)]
ASoC: omap: Fix build errors in ams-delta
Fix "error: too few arguments to function 'ams_delta_set_bias_level'"
build errors in ams-delta.c that were introduced after commit d4c6005 ("ASoC:
Add context parameter to card DAPM callbacks") by adding dapm context
to ams_delta_set_bias_level calls.
Signed-off-by: Jarkko Nikula <jarkko.nikula@bitmer.com> Acked-by: Liam Girdwood <lrg@ti.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Sascha Hauer [Wed, 17 Aug 2011 07:20:01 +0000 (09:20 +0200)]
ASoC: Fix check for symmetric rate enforcement
The ASoC core tries to not enforce symmetric rates when
two streams open simultaneously. It does so by checking
rtd->rate being zero. This works exactly once after booting
because it is not set to zero again when the streams close.
Fix this by setting rtd->rate when no active stream is left.
[This leads to lots of warnings about not enforcing the symmetry in some
situations as there's a race in the userspace API where we know we've
got two applications but don't know what rates they want to set.
-- broonie ]
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Timur Tabi [Tue, 16 Aug 2011 22:47:45 +0000 (18:47 -0400)]
ASoC: claim the IRQ when the fsl_ssi device is probed, not opened
The PowerPC Freescale SSI driver is claiming the IRQ when the IRQ when
the device is opened, which means that the /proc/interrupts entry for
the SSI exists only during playback or capture. This also meant that
the user won't know that the IRQ number is wrong until he tries to use
the device. Instead, we should claim the IRQ when the device is probed.
Signed-off-by: Timur Tabi <timur@freescale.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
ASoC: DAPM: Allow multiple mixer sources to be routed via the same switch
Currently it is only possible to route one source per switch into a mixer.
This patch modifies the code, so that it is possible to route multiple sources
into a mixer via the same switch. One use-case for this is routing a stereo
channel pair into a mono-mixer via the same switch.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Mark Brown [Mon, 15 Aug 2011 02:01:02 +0000 (11:01 +0900)]
ASoC: Disable pulls on WM8994 AIF2 when starting it
Pull control is availalbe for WM8994 AIF2, generally disabled as part of
the GPIO configuration in order to save power after system startup. As on
newer devices in the series there is no GPIO functionality on these pins
this will happen less naturally so have the driver disable the pulls as the
AIF is probed.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Axel Lin [Sun, 14 Aug 2011 03:31:04 +0000 (11:31 +0800)]
ASoC: sta32x: shortcut the for loop to get ir and mcs
There is exactly one match or no match at all during the for loop iteration,
thus we can break from the for loop once a match is found.
Signed-off-by: Axel Lin <axel.lin@gmail.com> Acked-by: Johannes Stezenbach <js@sig21.net> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Axel Lin [Mon, 15 Aug 2011 08:38:34 +0000 (16:38 +0800)]
ASoC: nuc900-pcm: remove unused variable 'dai'
Remove unused variable 'dai' to eliminate below warning.
CC sound/soc/nuc900/nuc900-pcm.o
sound/soc/nuc900/nuc900-pcm.c: In function 'nuc900_dma_new':
sound/soc/nuc900/nuc900-pcm.c:321: warning: unused variable 'dai'
Signed-off-by: Axel Lin <axel.lin@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Axel Lin [Sat, 13 Aug 2011 13:27:16 +0000 (21:27 +0800)]
ASoC: soc-cache: Remove unneeded codec_drv pointer variable in snd_soc_lzo_get_blksize
Since commit aea170a099793abcd0e6de46b947458073204241
"ASoC: soc-cache: Add reg_size as a member to snd_soc_codec",
the codec_drv pointer variable is not used in snd_soc_lzo_get_blksize.
Signed-off-by: Axel Lin <axel.lin@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Axel Lin [Sat, 13 Aug 2011 13:12:01 +0000 (21:12 +0800)]
ASoC: soc-cache: Remove unneeded codec_drv pointer variable in snd_soc_flat_cache_init
Since commit d779fce5d79525d66269c8f6e430e1515d697f3d
"ASoC: soc-cache: Ensure flat compression uses a copy of the defaults cache",
the codec_drv pointer variable is not used any more.
Signed-off-by: Axel Lin <axel.lin@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Scott Jiang [Fri, 12 Aug 2011 22:04:13 +0000 (18:04 -0400)]
ASoC: Add spi hw read function for 16 addr 8 data mode for ad193x fix
[This will be used by the ad193x driver to fix the fact that the
original author of the driver put a bodge for their particular chip into
a the generic ASoC register I/O abstraction layer which looked like an
obvious bug which ended up getting fixed in 3.0. Sadly there were no
comments documenting what was going on. A minimally invasive correction
to the driver is to remove the register cache support and go direct to
the hardware all the time so we're adding a new feature -- broonie]
Signed-off-by: Scott Jiang <scott.jiang.linux@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Scott Jiang [Fri, 12 Aug 2011 22:04:11 +0000 (18:04 -0400)]
ASoC: ad193x: fix dac word len setting
dac word len value should left shift before setting
Signed-off-by: Scott Jiang <scott.jiang.linux@gmail.com> Acked-by: Barry Song <21cnbao@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: stable@kernel.org
ASoC: rx1950: Fix compilation error due to missing header
Add linux/types.h to fix this compilation error:
In file included from arch/arm/mach-s3c2410/include/mach/gpio-fns.h:27:0,
from arch/arm/mach-s3c2410/include/mach/gpio.h:27,
from /home/anarsoul/work/pda-linux/linux-next/arch/arm/include/asm/gpio.h:5,
from include/linux/gpio.h:18,
from sound/soc/samsung/rx1950_uda1380.c:20:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:29:34: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:30:34: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s5p_gpio_drvstr_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:57:2: error: expected specifier-qualifier-list before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:148:47: error: expected declaration specifiers or ‘...’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:156:24: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s3c_gpio_getpull’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:175:24: error: expected declaration specifiers or ‘...’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h: In function ‘s3c_gpio_cfgrange_nopull’:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: ‘s3c_gpio_pull_t’ undeclared (first use in this function)
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: expected ‘)’ before numeric constant
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: too many arguments to function ‘s3c_gpio_cfgall_range’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:174:12: note: declared here
arch/arm/plat-samsung/include/plat/gpio-cfg.h: At top level:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:199:26: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s5p_gpio_get_drvstr’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:210:50: error: expected declaration specifiers or ‘...’ before ‘s5p_gpio_drvstr_t’
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com> Acked-by: Jassi Brar <jassisinghbrar@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
ASoC: h1940: Fix compilation error due to missing header
Add linux/types.h to fix this compilation error:
In file included from arch/arm/mach-s3c2410/include/mach/gpio-fns.h:27:0,
from arch/arm/mach-s3c2410/include/mach/gpio.h:27,
from /home/anarsoul/work/pda-linux/linux-next/arch/arm/include/asm/gpio.h:5,
from include/linux/gpio.h:18,
from sound/soc/samsung/rx1950_uda1380.c:20:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:29:34: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:30:34: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s5p_gpio_drvstr_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:57:2: error: expected specifier-qualifier-list before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:148:47: error: expected declaration specifiers or ‘...’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:156:24: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s3c_gpio_getpull’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:175:24: error: expected declaration specifiers or ‘...’ before ‘s3c_gpio_pull_t’
arch/arm/plat-samsung/include/plat/gpio-cfg.h: In function ‘s3c_gpio_cfgrange_nopull’:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: ‘s3c_gpio_pull_t’ undeclared (first use in this function)
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: expected ‘)’ before numeric constant
arch/arm/plat-samsung/include/plat/gpio-cfg.h:180:47: error: too many arguments to function ‘s3c_gpio_cfgall_range’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:174:12: note: declared here
arch/arm/plat-samsung/include/plat/gpio-cfg.h: At top level:
arch/arm/plat-samsung/include/plat/gpio-cfg.h:199:26: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘s5p_gpio_get_drvstr’
arch/arm/plat-samsung/include/plat/gpio-cfg.h:210:50: error: expected declaration specifiers or ‘...’ before ‘s5p_gpio_drvstr_t’
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com> Acked-by: Jassi Brar <jassisinghbrar@gmail.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Mark Brown [Sat, 13 Aug 2011 02:50:48 +0000 (11:50 +0900)]
ASoC: Support !CONFIG_REGMAP builds
Since we changed regmap to be selected and register per bus rather than
via the core only we can't rely on it being enabled by the ASoC core.
Support compiling it out.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reported-by: Axel Lin <axel.lin@gmail.com>
Mark Brown [Wed, 10 Aug 2011 08:47:33 +0000 (17:47 +0900)]
ASoC: Disable WM8994 VMID for digital only paths
On WM8994 class devices only the analogue portions of the CODEC require
VMID so when running digital only paths we can leave VMID disabled.
On some earlier devices the FLL uses VMID so we don't use DAPM reference
counting alone, we maintain an internal reference count which is also
enabled and disabled by the FLL startup.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Mark Brown [Fri, 15 Jul 2011 06:12:31 +0000 (15:12 +0900)]
ASoC: Add VMID widget for wm_hubs devices
Currently this does not actually do anything, it is being introduced in
order to facilitate additional power optimisations for current generation
devices.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Stephen Warren [Thu, 11 Aug 2011 17:59:11 +0000 (11:59 -0600)]
ASoC: soc-io: Fix CONFIG_REGMAP_I2C/SPI guards to support regmap modules
When CONFIG_REGMAP_I2C/SPI are m, CONFIG_REGMAP_I2C_MODULE is set in the
pre-processor instead of CONFIG_REGMAP_I2C. This removes SND_SOC_I2C as a
valid option for snd_soc_codec_set_cache_io()'s control parameter, and
causes any ASoC regmap-using codec built as a module to fail to initialize.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Mark Brown [Thu, 4 Aug 2011 09:13:45 +0000 (18:13 +0900)]
ASoC: Allow userspace control of Speyside headphone output
In order to facilitate the widest range of use cases (especially things
like speakerphone) allow the headphone output to be enabled and disabled
by the application layer.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Jarkko Nikula [Thu, 11 Aug 2011 12:44:57 +0000 (15:44 +0300)]
ASoC: omap: Update e-mail address of Jarkko Nikula
My gmail account got disabled and I'm not going to reopen it.
Signed-off-by: Jarkko Nikula <jarkko.nikula@bitmer.com> Acked-by: Liam Girdwood <lrg@ti.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Stephen Warren [Thu, 4 Aug 2011 22:44:44 +0000 (16:44 -0600)]
ASoC: WM8903: Free IRQ on device removal
Without this, request_irq on subsequent device initialization fails, and
the codec cannot be used.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Acked-by: Liam Girdwood <lrg@ti.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Stephen Warren [Thu, 4 Aug 2011 22:44:43 +0000 (16:44 -0600)]
ASoC: Tegra: wm8903 machine driver: Allow re-insertion of module
Two issues were preventing module snd-soc-tegra-wm8903.ko from being
removed and re-inserted:
a) The speaker-enable GPIO is hosted by the WM8903 chip. This GPIO must
be freed before snd_soc_unregister_card() is called, because that
triggers wm8903.c:wm8903_remove(), which calls gpiochip_remove(), which
then fails if any of the GPIOs are in use. To solve this, free all GPIOs
first, so the code doesn't care where they come from.
b) We need to call snd_soc_jack_free_gpios() to match the call to
snd_soc_jack_add_gpios() during initialization. Without this, the
call to snd_soc_jack_add_gpios() fails during any subsequent modprobe
and initialization, since the GPIO and IRQ are already registered. In
turn, this causes the headphone state not to be monitored, so the
headphone is assumed not to be plugged in, and the audio path to it is
never enabled.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Cc: stable@kernel.org Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Not all PCM devices have all sub-streams. Specifically, the SPDIF driver
only supports playback and hence has no capture substream. Check whether
a substream exists before dereferencing it, when de-allocating DMA
buffers in tegra_pcm_deallocate_dma_buffer.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Acked-by: Liam Girdwood <lrg@ti.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: stable@kernel.org
Mark Brown [Sun, 24 Jul 2011 11:23:37 +0000 (12:23 +0100)]
ASoC: Add regmap as a control type
Allow drivers to set up their own regmap API structures. This is mainly
useful with MFDs where the core driver will have set up regmap at the
minute, though it may make sense to push the existing regmap setup out
of the core into the drivers.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Mark Brown [Mon, 13 Jun 2011 18:35:29 +0000 (19:35 +0100)]
ASoC: Use new register map API for ASoC generic physical I/O
Remove all the ASoC specific physical I/O code and replace it with calls
into the regmap API. The bulk write code can only be used safely if all
regmap calls are locked with the CODEC lock, we need to add bulk support
to the regmap API or replace the code with an open coded loop (though
currently it has no users...).
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: Liam Girdwood <lrg@ti.com>
Mark Brown [Wed, 20 Jul 2011 12:49:58 +0000 (13:49 +0100)]
ASoC: Acknowledge WM8996 interrupts before acting on them
This closes the small race between a status being read in response to an
interrupt and clearing the interrupt, meaning that if the status changes
between those periods we might not get a reassertion of the interrupt.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Commit d006199e72a9 ("serial: sh-sci: Regtype probing doesn't need to be
fatal.") made sci_init_single() return when sci_probe_regmap() succeeds,
although it should return when sci_probe_regmap() fails. This causes
systems using the serial sh-sci driver to crash during boot.
Fix the problem by using the right return condition.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Sun, 7 Aug 2011 21:07:03 +0000 (14:07 -0700)]
arm: remove "optimized" SHA1 routines
Since commit 1eb19a12bd22 ("lib/sha1: use the git implementation of
SHA-1"), the ARM SHA1 routines no longer work. The reason? They
depended on the larger 320-byte workspace, and now the sha1 workspace is
just 16 words (64 bytes). So the assembly version would overwrite the
stack randomly.
The optimized asm version is also probably slower than the new improved
C version, so there's no reason to keep it around. At least that was
the case in git, where what appears to be the same assembly language
version was removed two years ago because the optimized C BLK_SHA1 code
was faster.
Reported-and-tested-by: Joachim Eastwood <manabian@gmail.com> Cc: Andreas Schwab <schwab@linux-m68k.org> Cc: Nicolas Pitre <nico@fluxnic.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Al Viro [Sun, 7 Aug 2011 17:55:11 +0000 (18:55 +0100)]
fix rcu annotations noise in cred.h
task->cred is declared as __rcu, and access to other tasks' ->cred is,
indeed, protected. Access to current->cred does not need rcu_dereference()
at all, since only the task itself can change its ->cred. sparse, of
course, has no way of knowing that...
Add force-cast in current_cred(), make current_fsuid() et.al. use it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Sun, 7 Aug 2011 16:53:20 +0000 (09:53 -0700)]
vfs: rename 'do_follow_link' to 'should_follow_link'
Al points out that the do_follow_link() helper function really is
misnamed - it's about whether we should try to follow a symlink or not,
not about actually doing the following.
Ari Savolainen [Sat, 6 Aug 2011 16:43:07 +0000 (19:43 +0300)]
Fix POSIX ACL permission check
After commit 3567866bf261: "RCUify freeing acls, let check_acl() go ahead in
RCU mode if acl is cached" posix_acl_permission is being called with an
unsupported flag and the permission check fails. This patch fixes the issue.
Signed-off-by: Ari Savolainen <ari.m.savolainen@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Linus Torvalds [Sun, 7 Aug 2011 05:56:03 +0000 (22:56 -0700)]
Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd
* 'for-linus' of git://git.open-osd.org/linux-open-osd:
ore: Make ore its own module
exofs: Rename raid engine from exofs/ios.c => ore
exofs: ios: Move to a per inode components & device-table
exofs: Move exofs specific osd operations out of ios.c
exofs: Add offset/length to exofs_get_io_state
exofs: Fix truncate for the raid-groups case
exofs: Small cleanup of exofs_fill_super
exofs: BUG: Avoid sbi realloc
exofs: Remove pnfs-osd private definitions
nfs_xdr: Move nfs4_string definition out of #ifdef CONFIG_NFS_V4
Linus Torvalds [Sun, 7 Aug 2011 05:45:50 +0000 (22:45 -0700)]
vfs: optimize inode cache access patterns
The inode structure layout is largely random, and some of the vfs paths
really do care. The path lookup in particular is already quite D$
intensive, and profiles show that accessing the 'inode->i_op->xyz'
fields is quite costly.
We already optimized the dcache to not unnecessarily load the d_op
structure for members that are often NULL using the DCACHE_OP_xyz bits
in dentry->d_flags, and this does something very similar for the inode
ops that are used during pathname lookup.
It also re-orders the fields so that the fields accessed by 'stat' are
together at the beginning of the inode structure, and roughly in the
order accessed.
The effect of this seems to be in the 1-2% range for an empty kernel
"make -j" run (which is fairly kernel-intensive, mostly in filename
lookup), so it's visible. The numbers are fairly noisy, though, and
likely depend a lot on exact microarchitecture. So there's more tuning
to be done.