avoids the following section missmatch
|WARNING: drivers/usb/gadget/g_audio.o(.init.text+0x2e7): Section
|mismatch in reference from the function afunc_bind() to the function
|.devexit.text:snd_uac2_remove()
|The function __init afunc_bind() references
|a function __devexit snd_uac2_remove().
|This is often seen when error handling in the init function
|uses functionality in the exit path.
|The fix is often to remove the __devexit annotation of
|snd_uac2_remove() so it may be used outside an exit section.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
It was moved to be an argument in 07a18bd716 ("usb gadget: don't
save bind callback in struct usb_composite_driver"). The reason was to
avoid the section missmatch. The warning was shown because ->bind is
marked as __init becuase it is a one time init. The warning can be also
suppresed by whitelisting the variable i.e. rename it to lets say _probe.
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
The first item on the todo list is a new user interface. Put this
information into Kconfig's help entry to people are not too confusing
once an user API changes which does not happen in kernel otherwise.
Cc: devel@driverdev.osuosl.org
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Driver for the "USB20D" / "USBD" block on BCM6328, BCM6368, BCM6816,
BCM6362, BCM3383, and others.
The hardware block was designed to support networking applications
(direct connection of a home router to a PC), and the endpoint
configuration is fixed.
[ balbi@ti.com : dropped USB_GADGET_DUALSPEED from Kconfig ]
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Felipe Balbi <balbi@ti.com>
devm_* functions are already used in this file. Hence
convert clk_get to devm_clk_get for completeness.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Silences the following type of sparse warnings:
warning: Using plain integer as NULL pointer
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Silences the following checkpatch warning:
WARNING: sizeof *hsreq should be sizeof(*hsreq)
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
devm_* functions are used to replace kzalloc, request_mem_region, ioremap
clk_get and request_irq functions in probe call. With the usage of devm_*
functions explicit freeing and unmapping is not required.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Change the call to PTR_ERR to access the value just tested by IS_ERR.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@@
expression e,e1;
@@
(
if (IS_ERR(e)) { ... PTR_ERR(e) ... }
|
if (IS_ERR(e=e1)) { ... PTR_ERR(e) ... }
|
*if (IS_ERR(e))
{ ...
* PTR_ERR(e1)
... }
)
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit removes USB_GADGET_DUALSPEED and USB_GADGET_SUPERSPEED
Kconfig options. Since now kernel allows many UDC drivers to be
compiled, those options may turn to no longer be valid. For
instance, if someone decides to build UDC that supports super
speed and UDC that supports high speed only, the latter will be
"assumed" to support super speed since USB_GADGET_SUPERSPEED will
be selected by the former.
The test of whether CONFIG_USB_GADGET_*SPEED was defined was just
an optimisation which removed otherwise dead code (ie. if UDC is
not dual speed, there is no need to handle cases that can happen
if speed is high). This commit removes those checks.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
'req' being a pointer shouldn't be equated with 0.
Fixes the following compilation warning:
drivers/usb/gadget/s3c2410_udc.c:1299:13: warning:
Using plain integer as NULL pointer
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Fixes the following checkpatch errors:
ERROR: do not use assignment in if condition
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Silences about 75 errors and warnings related to
- Spacing
- Alignment of braces
- Line over 80 characters
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Fixes the following warning:
WARNING: Use #include <linux/io.h> instead of <asm/io.h>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This patch (as1599) fixes dummy-hcd to make it update the appropriate
driver pointer when a new gadget driver is bound or unbound. Without
this change, the gadget driver's name doesn't appear in dev_printk
output.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>
The lpc32xx_udc driver supported only one controller by defining a global
static struct for it. This patch enables multiple instances of the controller
by dynamic allocation of the struct at probe(). A static struct is kept as a
template on initialization since it does some complex preset, reflecting fixed
hardware endpoint structure.
Signed-off-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This patch removes the utilization of struct usb_endpoint_descriptor, as done
by other drivers also. This was done on request by the USB gadget maintainers,
since this API is obsoleted.
Signed-off-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This patch adjusts the LPC32xx USB gadget driver to the new udc_start /
udc_stop interface.
Signed-off-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
When IORESOURCE_IRQ_SHAREABLE is set, the irq handler may be called
even if the interupt of the USB module doesn't happen. So, it may
clear the interrupt flags by mistake. This patch fixes it.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
%pm already provides pretty print for mac addresses, let's
use that and drop homebrew mac address printing.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
usb_gadget_remove_driver() runs through a four-step sequence to shut down
the gadget driver. For the case of a composite gadget + at91 UDC, this
would look like:
udc->driver->disconnect(udc->gadget); // composite_disconnect()
usb_gadget_disconnect(udc->gadget); // at91_pullup(gadget, 0)
udc->driver->unbind(udc->gadget); // composite_unbind()
usb_gadget_udc_stop(udc->gadget, udc->driver); // at91_stop()
The UDC driver can receive SETUP packets from the host up until the
point when usb_gadget_disconnect() returns. On rare occasions, the
gadget driver may see this sequence:
udc->driver->disconnect(udc->gadget); // composite_disconnect()
udc->driver->setup(udc->gadget, &ctrl); // composite_setup()
udc->driver->unbind(udc->gadget); // composite_unbind()
Some gadget drivers, such as composite, assume this will never happen
and crash as a result.
The fix is to quiesce the UDC hardware (via usb_gadget_disconnect)
before running the gadget driver through the disconnect/unbind sequence.
Reviewed-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
The timeout values were 1000 and timeout issue occured many times on my
s3c6410 Soc based board (mostly when booting whith USB cable not
connected). This patch increase the values to 10000 to guarantee the
success of reset.
Having set timeout to 10000, I printed the remained timeout values
which could cause timeout issue before this change (tested several
times).
the first timeout value remained:
timeout = 8079
timeout = 8079
timeout = 8078
timeout = 8081
the second timeout value remained:
timeout = 7940
timeout = 7945
timeout = 7940
timeout = 7938
Seeing from above values, I think the value 10000 is big enough.
Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Fix boot up hang when enable udc without otg enabled.
The root cause is that the clock will be shut down when probe routine is
finished because of clock gating. When a gadget driver is registered at
this time, it will call mv_udc_start which in turn will call
mv_udc_vbus_session. If there is no cable attached at the boot up time,
the vbus is low, so it will call stop_activity path without clock
enabled which will cause system hang then.
Actually, we need't go this path when clock is disabled, what we need to
do is just jump out.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Fix system hang in udc shutdown routine which caused by accessing usb
register when clock is disabled. So enable usb clock before access
register.
Signed-off-by: Yunfan Zhang <yfzhang@marvell.com>
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
In order to support iso, we need do the following things:
1. fix length for one dtd
2. allow req contains multiple packets for a ISO transfer
Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Yu Xu <yuxu@marvell.com>
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
According to ChipIdea's reference manual in section 8.5.2
"Non-streaming operational mode in device mode", we'd better enable stream
mode, especially that ISO endpoints are not supported when the SDIS bit
is set.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
build_dtd() can be called when hold a spinlock, but GFP_KERNEL may cause
dma_pool_alloc() sleep, So we need use GFP_ATOMIC instead of GFP_KERNEL.
But using GFP_ATOMIC may cause failure when allocating memory, add error
handler to handle it.
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
There are several places use udelay(LOOPS_USEC) to wait the status to be
changed, but the delay interval is a bit too long, so reduce it to
enhance the performance.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Following a report of a crash during an automount expire I found that
the locking in fs/autofs4/expire.c:get_next_positive_subdir() was wrong.
Not only is the locking wrong but the function is more complex than it
needs to be.
The function is meant to calculate (and dget) the next entry in the list
of directories contained in the root of an autofs mount point (an autofs
indirect mount to be precise). The main problem was that the d_lock of
the owner of the list was not being taken when walking the list, which
lead to list corruption under load. The only other lock that needs to
be taken is against the next dentry candidate so it can be checked for
usability.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)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=fUJz
-----END PGP SIGNATURE-----
Merge tag 'vfio-for-v3.6-rc1' of git://github.com/awilliam/linux-vfio
Pull VFIO fix from Alex Williamson:
"Just a trivial patch to include vfio.h in the installed headers so we
can complete userspace integration into QEMU."
* tag 'vfio-for-v3.6-rc1' of git://github.com/awilliam/linux-vfio:
vfio: Include vfio.h in installed headers
* On machines with large MMIO/PCI E820 spaces we fail to boot b/c
we failed to pre-allocate large enough virtual space for extend_brk.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)
iQEcBAABAgAGBQJQKlV9AAoJEFjIrFwIi8fJZh4H/0ZlRrgG+8mqwCM+pcyYY+2a
zqnOrfYUO/aO26oqiOQUrn4quLAElhBuJK19uSj8fckMMZ+sr5rTJTaXmT6b7F7N
pgTXsKQCYAJ2NNGHVSQ73KYjOUeEW3woDSQZo0y/GRzOjiQsxpoFc8PS94ZieUNT
G6a8ECZBRv3fz8nAuJlhGV/suqHGOLJ0pwum1gHGOzaH3ZoZVtaQv5LhGYctJspU
yF5bdeD0qjCbseVtJ72tyxzLxMwLpJtdy2MbSwIv5JGuszj0nRmL4oa7Vc4vYdyv
p+FrNmbDAZ1j61z1PhBZPmgzwba2LTXtIWhR2zsGJgqlJNzMUtlNkff1kT3NeE0=
=Gl6V
-----END PGP SIGNATURE-----
Merge tag 'stable/for-linus-3.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Pull Xen fix from Konrad Rzeszutek Wilk:
"Way back in v3.5 we added a mechanism to populate back pages that were
released (they overlapped with MMIO regions), but neglected to reserve
the proper amount of virtual space for extend_brk to work properly.
Coincidentally some other commit aligned the _brk space to larger area
so I didn't trigger this until it was run on a machine with more than
2GB of MMIO space."
* On machines with large MMIO/PCI E820 spaces we fail to boot b/c
we failed to pre-allocate large enough virtual space for extend_brk.
* tag 'stable/for-linus-3.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/p2m: Reserve 8MB of _brk space for P2M leafs when populating back.
Moved to djbw@fb.com
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Signed-off-by: Dan Williams <djbw@fb.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When dumping "Code: " sections from an oops, the trapping instruction
%rip points to can be a string copy
2b:* f3 a5 rep movsl %ds:(%rsi),%es:(%rdi)
and the line contain a bunch of ":". Current "cut" selects only the and
the second field output looks funnily overlaid this:
2b:* f3 a5 rep movsl %ds <-- trapping instruction:(%rsi),%es:(%rdi
Fix this by selecting the remaining fields too.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kbuild@vger.kernel.org
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull two slave-dmaengine fixes from Vinod Koul:
"One fixes the correct use of clock API in imx driver and the other
enables clock for tegra driver, which is used for other tegra driver
conversion to dmanegine in -next."
* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
dma: tegra: enable/disable dma clock
dma: imx-dma: Fix kernel crash due to missing clock conversion
Pull more drm fixes from Dave Airlie:
"Just some intel and nouveau ones this time, intel has more edp panel
fixes for macbooks and nouveau has a suspend/resume regression fix in
there."
* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
drm/i915: Apply post-sync write for pipe control invalidates
drm/i915: reorder edp disabling to fix ivb MacBook Air
drm/nv86/fifo: suspend fix
drm/nouveau: disable copy engine on NVAF
nouveau: fixup scanout enable in nvc0_pm
drm/nouveau/aux: mask off higher bits of auxch index in i2c table entry
drm/nvd0/disp: mask off high 16 bit of negative cursor x-coordinate
drm/i915: ensure i2c adapter is all set before adding it
drm/i915: ignore eDP bpc settings from vbt
drm/i915: Fix blank panel at reopening lid
drm/nve0/fifo: add support for the flip completion swmthd
Pull two sparc fixes from David S. Miller.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
sparc64: Be less verbose during vmemmap population.
sparc64: do not clobber personality flags in sys_sparc64_personality()
* 'drm-nouveau-fixes' of git://git.freedesktop.org/git/nouveau/linux-2.6:
drm/nv86/fifo: suspend fix
drm/nouveau: disable copy engine on NVAF
nouveau: fixup scanout enable in nvc0_pm
drm/nouveau/aux: mask off higher bits of auxch index in i2c table entry
drm/nvd0/disp: mask off high 16 bit of negative cursor x-coordinate
drm/nve0/fifo: add support for the flip completion swmthd
Daniel Vetter writes:
"A few important fixers:
- fix various lvds backlight issues, regressed in 3.6 (Takashi Iwai)
- make the retina mbp work (ignore bogus edp bpc value in vbt)
- fix a gmbus regression introduced in (iirc) 3.4 (Jani Nikula)
- fix an edp panel power sequence regression, fixes the new macbook air
- apply the tlb invalidate w/a
Otherwise we still have another gmbus regression (patches are awaiting
tested-bys) and there's something odd going with some rare systems not
entering rc6 often enough (and hence blowing through too much power). It
seems to be a timing-related issue and can be mitigated by frobbing the
magic tuning parameters. We're still working on that one. Also, we still
have some fallout from the hw context support, but you can only hit that
with mesa master."
* 'drm-intel-fixes' of git://people.freedesktop.org/~danvet/drm-intel:
drm/i915: Apply post-sync write for pipe control invalidates
drm/i915: reorder edp disabling to fix ivb MacBook Air
drm/i915: ensure i2c adapter is all set before adding it
drm/i915: ignore eDP bpc settings from vbt
drm/i915: Fix blank panel at reopening lid
On a 2-node machine with 256GB of ram we get 512 lines of
console output, which is just too much.
This mimicks Yinghai Lu's x86 commit c2b91e2eec
(x86_64/mm: check and print vmemmap allocation continuous) except that
we aren't ever going to get contiguous block pointers in between calls
so just print when the virtual address or node changes.
This decreases the output by an order of 16.
Also demote this to KERN_DEBUG.
Signed-off-by: David S. Miller <davem@davemloft.net>
When invalidating the TLBs it is documentated as requiring a post-sync
write. Failure to do so seems to result in a GPU hang.
Exposure to this hang on IVB seems to be a result of removing the extra
stalls required for SNB pipecontrol workarounds:
commit 6c6cf5aa9c
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Jul 20 18:02:28 2012 +0100
drm/i915: Only apply the SNB pipe control w/a to gen6
Note: Manually switch the pipe_control cmd to 4 dwords to avoid a
(silent) functional conflict with -next. This way will get a loud (but
conflict with next (since the scratch_addr has been deleted there).
Reported-and-tested-by: yex.tian@intel.com
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=53322
Acked-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: added note about merge conflict with -next.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
eDP is tons of fun. It turns out that at least the new MacBook Air 5,1
model absolutely doesn't like the new force vdd dance we've introduced
in
commit 6cb49835da
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Sun May 20 17:14:50 2012 +0200
drm/i915: enable vdd when switching off the eDP panel
But that patch also tried to fix some neat edp sequence issue with the
force_vdd timings. Closer inspection reveals that we've raised
force_vdd only to do the aux channel communication dp_sink_dpms. If we
move the edp_panel_off below that, we don't need any force_vdd for the
disable sequence, which makes the Air happy.
Unfortunately the reporter of the original bug that the above commit
fixed is travelling, so we can't test whether this regresses things.
But my theory is that since we don't check for any power-off ->
force_vdd-on delays in edp_panel_vdd_on, this was the actual
root-cause of this failure. With that force_vdd dance completely
eliminated, I'm hopeful the original bug stays fixed, too.
For reference the old bug, which hopefully doesn't get broken by this:
https://bugzilla.kernel.org/show_bug.cgi?id=43163
In any case, regression fixers win over plain bugfixes, so this needs
to go in asap.
v2: The crucial pieces seems to be to clear the force_vdd flag
uncoditionally, too, in edp_panel_off. Looks like this is left behind
by the firmware somehow.
v3: The Apple firmware seems to switch off the panel on it's own, hence
we still need to keep force_vdd on, but properly clear it when switching
the panel off.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=45671
Tested-by: Roberto Romer <sildurin@gmail.com>
Tested-by: Daniel Wagner <wagi@monom.org>
Tested-by: Keith Packard <keithp@keithp.com>
Cc: stable@vger.kernel.org
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Pull s390 patches from Martin Schwidefsky:
"Included are bug fixes and a patch to enable system call filtering
with BPF."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/compat: fix mmap compat system calls
s390/compat: fix compat wrappers for process_vm system calls
s390: do not clobber personality flags in sys_32_personality()
s390/seccomp: add support for system call filtering using BPF
s390/sclp_sdias: Add missing break and "fall through"
s390/mm: remove MAX_PHYSADDR_BITS define