The register belongs to the DSS, move the feature to the dss_features
structure.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The num_ovls and num_mgrs are dispc features. Move them from the
omap_dss_features structure to the dispc_features structure.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The overlay_caps is a dispc feature. Move it from the omap_dss_features
structure to the dispc_features structure.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The supported_color_modes is a dispc feature. Move it from the
omap_dss_features structure to the dispc_features structure.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The buffer_size_unit and burst_size_unit are dispc features. Move them
from the omap_dss_features structure to the dispc_features structure.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

In preparation for removal of the core module, move the shutdown()
handler from core to dss.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

debugfs code is spread between the core and dss drivers. In preparation
for removal of the core driver, move it all to the dss driver.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The DSS internal features are derived from the platform device
compatible string which is available at probe time. Don't delay
initialization until bind time. This prepares for the merge of the two
DSS features structures that will be needed before the DSS is bound.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The dss driver uses the supported display types to check whether the DSS
has SDI, VENC or HDMI outputs. We can instead use the supported outputs
the provide the same information. This removes the last use of the
supported display types, that we can then remove as well.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Use the compatible string instead of the OMAP SoC revision to determine
device features. The various OMAP3-based SoCs can't be told apart using
the compatible string, use soc_device_match() to tell them apart.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The DPI code only needs to differentiate between major OMAP revisions,
which can be obtained from the DSS compatible string. Replace the OMAP
SoC model checks to prepare for removal of the OMAP SoC version platform
data.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Use the compatible string instead of the OMAP SoC revision to determine
device features. On OMAP34xx the features depend on the ES revision that
can not be determined from the compatible string. Use soc_device_match()
in that case.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The OMAP implementation of the set_min_bus_tput() API is a no-op.
There's no point in forwarding the driver calls to the platform code.
Remove the use of the related platform data callback, but keep the
internal function as a reminder that the feature will need to be
implemented when the OMAP platform will provide support.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Don't rely on callback functions provided by the platform, but access
the syscon internally to mux the DSI pins.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The DSI PLL hardware data and DSS channels are selected based on the
OMAP SoC model. There's no need for fine-grained model information, as
the driver only needs to differentiate between OMAP3, OMAP4 and OMAP5.
As this can be done through the DSI compatible string, store the
corresponding information in OF match data instead to avoid accessing
the OMAP SoC model.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Move the two function pointers to a new dss_ops structure. This will
allow merging the dss_features and omap_dss_features structures without
having to expose the DPI source selection and LCD clock muxing functions
in header files.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

PHY features are stored in a global variable, while they should be
properties of the PHY object. As existing OMAP platforms have a single
HDMI PHY this doesn't cause any issue, but doesn't follow the driver
model.

Move the PHY features to the HDMI PHY data structure to follow the
driver model and pave the road for multiple HDMI PHYs support.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The two variables are never used outside of their compilation unit, make
them static.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The dpi_display_enable() function ensures that a VDDS_DSI regulator is
available if the DSI uses the VDDS_DSI supply. This is not needed, as a
failure to get the VDDS_DSI supply will result in a probe failure,
dpi_display_enable() will thus never be called in that case.

Remove the check, and replace tests for the FEAT_DPI_USES_VDDS_DSI
feature with a test for the regulator object.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

As non-DT booting is no longer supported, the only way to instantiate
the device is through an OF node, which is guaranteed to be present.
Remove the unneeded check.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

As non-DT booting is no longer supported, the only way to instantiate
the device is through an OF node, which is guaranteed to be present.
Remove the unneeded check.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

As non-DT booting is no longer supported, the only way to instantiate
the device is through an OF node, which is guaranteed to be present.
Remove the unneeded check.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group. So mark the non-const structs as const.

File size before:
  text	   data	    bss	    dec	    hex	filename
   4669	    464	      0	   5133	   140d	panel-dsi-cm.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   4725	    400	      0	   5125	   1405	panel-dsi-cm.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   5147	    560	      0	   5707	   164b	panel-sony-acx565akm.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   5211	    496	      0	   5707	   164b	panel-sony-acx565akm.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   2673	    368	      0	   3041	    be1	panel-tpo-td043mtea1.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   2721	    304	      0	   3025	    bd1	panel-tpo-td043mtea1.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

dma_buf_ops are not supposed to change at runtime. All functions
working with dma_buf_ops provided by <linux/dma-buf.h> work with
const dma_buf_ops. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   1240	    112	      0	   1352	    548 drivers/gpu/drm/omapdrm/omap_gem_dmabuf.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   1352	      0	      0	   1352	    548 drivers/gpu/drm/omapdrm/omap_gem_dmabuf.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The videomode structures are only copied into the vm field of a
panel_drv_data structure, so they can be const.

Done with the help of Coccinelle.
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Use interrupt handler for hpd GPIO to react to HPD changes.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

If the hpd_gpio is valid, use interrupt handler to react to HPD changes.
In case the hpd_gpio is not valid, try to enable hpd detection on the
encoder if it supports it.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The HPD signal can be used for detecting HDMI cable plug and unplug event
without the need for polling the status of the line.
This will speed up detecting such event because we do not need to wait for
the next poll event to notice the state change.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

omap_framebuffer_create() fails to unref all the gem objects if creating
the FB fails, leading to a memory leak.

Fix the loop so that it goes through all the reffed gem objects.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

All the MTD block write requests are failing with
following error messages

    mkfs.ext4  /dev/mtdblock0

    print_req_error: I/O error, dev mtdblock0, sector 0
    Buffer I/O error on dev mtdblock0, logical block 0,
    lost async page write

The control is going to default case after block write request
because of missing return.

Fixes: commit 2a842aca ("block: introduce new block status code type")
Signed-off-by: NAbhishek Sahu <absahu@codeaurora.org>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

Commit c54451a5 "iommu/arm-smmu: Fix the error path in arm_smmu_add_device"
removed fwspec assignment in legacy_binding path as redundant which is
wrong. It needs to be updated after fwspec initialisation in
arm_smmu_register_legacy_master() as it is dereferenced later. Without
this there is a NULL-pointer dereference panic during boot on some hosts.
Signed-off-by: NArtem Savkov <asavkov@redhat.com>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

Here is a device has xen-pirq-MSI interrupt. Dom0 might lost interrupt
during driver irq_disable/irq_enable. Here is the scenario,
 1. irq_disable -> disable_dynirq -> mask_evtchn(irq channel)
 2. dev interrupt raised by HW and Xen mark its evtchn as pending
 3. irq_enable -> startup_pirq -> eoi_pirq ->
    clear_evtchn(channel of irq) -> clear pending status
 4. consume_one_event process the irq event without pending bit assert
    which result in interrupt lost once
 5. No HW interrupt raising anymore.

Now use enable_dynirq for enable_pirq of xen_pirq_chip to remove
eoi_pirq when irq_enable.
Signed-off-by: NLiu Shuo <shuo.a.liu@intel.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NJuergen Gross <jgross@suse.com>

When starting the xenwatch thread a theoretical deadlock situation is
possible:

xs_init() contains:

    task = kthread_run(xenwatch_thread, NULL, "xenwatch");
    if (IS_ERR(task))
        return PTR_ERR(task);
    xenwatch_pid = task->pid;

And xenwatch_thread() does:

    mutex_lock(&xenwatch_mutex);
    ...
    event->handle->callback();
    ...
    mutex_unlock(&xenwatch_mutex);

The callback could call unregister_xenbus_watch() which does:

    ...
    if (current->pid != xenwatch_pid)
        mutex_lock(&xenwatch_mutex);
    ...

In case a watch is firing before xenwatch_pid could be set and the
callback of that watch unregisters a watch, then a self-deadlock would
occur.

Avoid this by setting xenwatch_pid in xenwatch_thread().
Signed-off-by: NJuergen Gross <jgross@suse.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NJuergen Gross <jgross@suse.com>

comp_algorithm_store() passes the size of the source buffer to strlcpy()
instead of the destination buffer size.  Make it explicit that the two
buffers have the same size and use strcpy() instead of strlcpy().  The
latter can be done safely since the function ensures that the string in
the source buffer is terminated.

Link: http://lkml.kernel.org/r/20170803163350.45245-1-mka@chromium.orgSigned-off-by: NMatthias Kaehlcke <mka@chromium.org>
Reviewed-by: NDouglas Anderson <dianders@chromium.org>
Reviewed-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some Alpine Ridge LP DROMs (there might be others) erroneusly list more
ports than the controller actually has. Most probably because DROM of
the full Dual/Single port Thunderbolt controller was reused for LP
version. The current DROM parser does not check the upper bound thus it
leads to crash when sw->ports[] is accessed over bounds:

 BUG: unable to handle kernel NULL pointer dereference at 00000000000002ec
 IP: tb_drom_read+0x383/0x890 [thunderbolt]
 PGD 0
 P4D 0
 Oops: 0000 [#1] SMP
 CPU: 3 PID: 12248 Comm: systemd-udevd Not tainted 4.13.0-rc1-next-20170719 #1
 Hardware name: LENOVO 20HF000YGE/20HF000YGE, BIOS N1WET32W (1.11 ) 05/23/2017
 task: ffff8a293e4bcd80 task.stack: ffffa698027a8000
 RIP: 0010:tb_drom_read+0x383/0x890 [thunderbolt]
 RSP: 0018:ffffa698027ab990 EFLAGS: 00010246
 RAX: 0000000000000000 RBX: ffff8a2940af7800 RCX: 0000000000000000
 RDX: ffff8a2940ebb400 RSI: 0000000000000000 RDI: ffffa698027ab9a0
 RBP: ffffa698027ab9d0 R08: 0000000000000001 R09: 0000000000000002
 R10: ffff8a2940ebb5b0 R11: 0000000000000000 R12: ffff8a293bfa968c
 R13: 000000000000002c R14: 0000000000000056 R15: 0000000000000056
 FS:  00007f0a945a38c0(0000) GS:ffff8a2961580000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000000002ec CR3: 000000043e785000 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  tb_switch_add+0x9d/0x730 [thunderbolt]
  ? tb_switch_alloc+0x3cd/0x4d0 [thunderbolt]
  icm_start+0x5a/0xa0 [thunderbolt]
  tb_domain_add+0xc3/0xf0 [thunderbolt]
  nhi_probe+0x19e/0x310 [thunderbolt]
  local_pci_probe+0x42/0xa0
  pci_device_probe+0x18d/0x1a0
  driver_probe_device+0x2ff/0x450
  __driver_attach+0xa4/0xe0
  ? driver_probe_device+0x450/0x450
  bus_for_each_dev+0x6e/0xb0
  driver_attach+0x1e/0x20
  bus_add_driver+0x1d0/0x270
  ? 0xffffffffc0bbb000
  driver_register+0x60/0xe0
  ? 0xffffffffc0bbb000
  __pci_register_driver+0x4c/0x50
  nhi_init+0x28/0x1000 [thunderbolt]
  do_one_initcall+0x50/0x190
  ? __vunmap+0x81/0xb0
  ? _cond_resched+0x1a/0x50
  ? kmem_cache_alloc_trace+0x15f/0x1c0
  ? do_init_module+0x27/0x1e9
  do_init_module+0x5f/0x1e9
  load_module+0x24e7/0x2a60
  ? vfs_read+0x115/0x130
  SYSC_finit_module+0xfc/0x120
  ? SYSC_finit_module+0xfc/0x120
  SyS_finit_module+0xe/0x10
  do_syscall_64+0x67/0x170
  entry_SYSCALL64_slow_path+0x25/0x25

Fix this by making sure we only enumerate DROM port entries the hardware
actually has.
Reported-by: NChristian Kellner <ckellner@redhat.com>
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NLukas Wunner <lukas@wunner.de>
Tested-by: NChristian Kellner <ckellner@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

MEI device performs link reset during system suspend sequence.
The link reset cannot be performed while device is in
runtime suspend state. The resume sequence is bypassed with
suspend direct complete optimization,so the optimization should be
disabled for mei devices.

Fixes:
 [  192.940537] Restarting tasks ...
 [  192.940610] PGI is not set
 [  192.940619] ------------[ cut here ]------------ [  192.940623]
 WARNING: CPU: 0
 me.c:653 mei_me_pg_exit_sync+0x351/0x360 [  192.940624] Modules
 linked
 in:
 [  192.940627] CPU: 0 PID: 1661 Comm: kworker/0:3 Not tainted
 4.13.0-rc2+
 #2 [  192.940628] Hardware name: Dell Inc. XPS 13 9343/0TM99H, BIOS
 A11
 12/08/2016 [  192.940630] Workqueue: pm pm_runtime_work <snip> [
 192.940642] Call Trace:
 [  192.940646]  ? pci_pme_active+0x1de/0x1f0 [  192.940649]  ?
 pci_restore_standard_config+0x50/0x50
 [  192.940651]  ? kfree+0x172/0x190
 [  192.940653]  ? kfree+0x172/0x190
 [  192.940655]  ? pci_restore_standard_config+0x50/0x50
 [  192.940663]  mei_me_pm_runtime_resume+0x3f/0xc0
 [  192.940665]  pci_pm_runtime_resume+0x7a/0xa0 [  192.940667]
 __rpm_callback+0xb9/0x1e0 [  192.940668]  ?
 preempt_count_add+0x6d/0xc0 [  192.940670]  rpm_callback+0x24/0x90 [
 192.940672]  ? pci_restore_standard_config+0x50/0x50
 [  192.940674]  rpm_resume+0x4e8/0x800 [  192.940676]
 pm_runtime_work+0x55/0xb0 [  192.940678]
 process_one_work+0x184/0x3e0 [  192.940680]
 worker_thread+0x4d/0x3a0 [ 192.940681]  ?
 preempt_count_sub+0x9b/0x100 [  192.940683]
 kthread+0x122/0x140 [  192.940684]  ? process_one_work+0x3e0/0x3e0 [
 192.940685]  ? __kthread_create_on_node+0x1a0/0x1a0
 [  192.940688]  ret_from_fork+0x27/0x40 [  192.940690] Code: 96 3a
 9e ff 48 8b 7d 98 e8 cd 21 58 00 83 bb bc 01 00 00
 04 0f 85 40 fe ff ff e9 41 fe ff ff 48 c7 c7 5f 04 99 96 e8 93 6b 9f
 ff <0f> ff e9 5d fd ff ff e8 33 fe 99 ff 0f 1f 00 0f 1f 44 00 00 55
 [  192.940719] ---[ end trace
 a86955597774ead8 ]--- [  192.942540] done.
Suggested-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-by: NDominik Brodowski <linux@dominikbrodowski.net>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: NAlexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 0cb64249 ("firmware_loader: abort request if wait_for_completion
is interrupted") added via 4.0 added support to abort the fallback mechanism
when a signal was detected and wait_for_completion_interruptible() returned
-ERESTARTSYS -- for instance when a user hits CTRL-C. The abort was overly
*too* effective.

When a child process terminates (successful or not) the signal SIGCHLD can
be sent to the parent process which ran the child in the background and
later triggered a sync request for firmware through a sysfs interface which
relies on the fallback mechanism. This signal in turn can be recieved by the
interruptible wait we constructed on firmware_class and detects it as an
abort *before* userspace could get a chance to write the firmware. Upon
failure -EAGAIN is returned, so userspace is also kept in the dark about
exactly what happened.

We can reproduce the issue with the fw_fallback.sh selftest:

Before this patch:
$ sudo tools/testing/selftests/firmware/fw_fallback.sh
...
tools/testing/selftests/firmware/fw_fallback.sh: error - sync firmware request cancelled due to SIGCHLD

After this patch:
$ sudo tools/testing/selftests/firmware/fw_fallback.sh
...
tools/testing/selftests/firmware/fw_fallback.sh: SIGCHLD on sync ignored as expected

Fix this by making the wait killable -- only killable by SIGKILL (kill -9).
We loose the ability to allow userspace to cancel a write with CTRL-C
(SIGINT), however its been decided the compromise to require SIGKILL is
worth the gains.

Chances of this issue occuring are low due to the number of drivers upstream
exclusively relying on the fallback mechanism for firmware (2 drivers),
however this is observed in the field with custom drivers with sysfs
triggers to load firmware. Only distributions relying on the fallback
mechanism are impacted as well. An example reported issue was on Android,
as follows:

1) Android init (pid=1) fork()s (say pid=42) [this child process is totally
   unrelated to firmware loading, it could be sleep 2; for all we care ]
2) Android init (pid=1) does a write() on a (driver custom) sysfs file which
   ends up calling request_firmware() kernel side
3) The firmware loading fallback mechanism is used, the request is sent to
   userspace and pid 1 waits in the kernel on wait_*
4) before firmware loading completes pid 42 dies (for any reason, even
   normal termination)
5) Kernel delivers SIGCHLD to pid=1 to tell it a child has died, which
   causes -ERESTARTSYS to be returned from wait_*
6) The kernel's wait aborts and return -EAGAIN for the
   request_firmware() caller.

Cc: stable <stable@vger.kernel.org> # 4.0
Fixes: 0cb64249 ("firmware_loader: abort request if wait_for_completion is interrupted")
Suggested-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Suggested-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: NMartin Fuzzey <mfuzzey@parkeon.com>
Reported-by: NMartin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix batched requests from waiting forever on failure.

The firmware API batched requests feature has been broken since the API call
request_firmware_direct() was introduced on commit bba3a87e ("firmware:
Introduce request_firmware_direct()"), added on v3.14 *iff* the firmware
being requested was not present in *certain kernel builds* [0].

When no firmware is found the worker which goes on to finish never informs
waiters queued up of this, so any batched request will stall in what seems
to be forever (MAX_SCHEDULE_TIMEOUT). Sadly, a reboot will also stall, as
the reboot notifier was only designed to kill custom fallback workers. The
issue seems to the user as a type of soft lockup, what *actually* happens
underneath the hood is a wait call which never completes as we failed to
issue a completion on error.

For device drivers with optional firmware schemes (ie, Intel iwlwifi, or
Netronome -- even though it uses request_firmware() and not
request_firmware_direct()), this could mean that when you boot a system with
multiple cards the firmware will seem to never load on the system, or that
the card is just not responsive even the driver initialization. Due to
differences in scheduling possible this should not always trigger --
one would need to to ensure that multiple requests are in place at the
right time for this to work, also release_firmware() must not be called
prior to any other incoming request. The complexity may not be worth
supporting batched requests in the future given the wait mechanism is
only used also for the fallback mechanism. We'll keep it for now and
just fix it.

Its reported that at least with the Intel WiFi cards on one system this
issue was creeping up 50% of the boots [0].

Before this commit batched requests testing revealed:
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=y

Most common Linux distribution setup.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     FAIL                OK
request_firmware_direct()              FAIL                OK
request_firmware_nowait(uevent=true)   FAIL                OK
request_firmware_nowait(uevent=false)  FAIL                OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=n

Only possible if CONFIG_DELL_RBU=n and CONFIG_LEDS_LP55XX_COMMON=n, rare.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     FAIL                OK
request_firmware_direct()              FAIL                OK
request_firmware_nowait(uevent=true)   FAIL                OK
request_firmware_nowait(uevent=false)  FAIL                OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
CONFIG_FW_LOADER_USER_HELPER=y

Google Android setup.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     OK                  OK
request_firmware_direct()              FAIL                OK
request_firmware_nowait(uevent=true)   OK                  OK
request_firmware_nowait(uevent=false)  OK                  OK
============================================================================

Ater this commit batched testing results:
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=y

Most common Linux distribution setup.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     OK                  OK
request_firmware_direct()              OK                  OK
request_firmware_nowait(uevent=true)   OK                  OK
request_firmware_nowait(uevent=false)  OK                  OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=n

Only possible if CONFIG_DELL_RBU=n and CONFIG_LEDS_LP55XX_COMMON=n, rare.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     OK                  OK
request_firmware_direct()              OK                  OK
request_firmware_nowait(uevent=true)   OK                  OK
request_firmware_nowait(uevent=false)  OK                  OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
CONFIG_FW_LOADER_USER_HELPER=y

Google Android setup.

API-type                               no-firmware-found   firmware-found
----------------------------------------------------------------------
request_firmware()                     OK                  OK
request_firmware_direct()              OK                  OK
request_firmware_nowait(uevent=true)   OK                  OK
request_firmware_nowait(uevent=false)  OK                  OK
============================================================================

[0] https://bugzilla.kernel.org/show_bug.cgi?id=195477

Cc: stable <stable@vger.kernel.org> # v3.14
Fixes: bba3a87e ("firmware: Introduce request_firmware_direct()"
Reported-by: NNicolas <nbroeking@me.com>
Reported-by: NJohn Ewalt  <jewalt@lgsinnovations.com>
Reported-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>