l2x0_of_init function is always defined
arch/arm/include/asm/hardware/cache-l2x0.h: in case of
CONFIG_CACHE_L2X0 is not selected then a placeholder is defined.
Then there is no need to have ifdef around  l2x0_of_init.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397925170-8202-2-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The cpuidle is a platform driver so we register the device just after
the initialization of the board in an arch_initcall.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-12-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Add the wfi, cpu idle and cpu deep idle power states support for the
Armada XP SoCs.

All the latencies and the power consumption values used at the
"armada_370_xp_idle_driver" structure are preliminary and will be
modified in the future after running some measurements and analysis.

Based on the work of Nadav Haklai.
Signed-off-by: NNadav Haklai <nadavh@marvell.com>
Link: https://lkml.kernel.org/r/1397488214-20685-11-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-11-git-send-email-gregory.clement@free-electrons.comAcked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

In order to have well encapsulated code, we use notifier callbacks for
CPU_PM_ENTER and CPU_PM_EXIT inside the mvebu power management code.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-10-git-send-email-gregory.clement@free-electrons.comAcked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

Following the integration into mach-mvebu of the Kirkwood ARMv5
support, we need to be more careful about which files get built. For
example, the pmsu.c file now calls wfi(), which only exists on ARMv7
platforms.

Therefore, this commit changes mach-mvebu/Makefile to build the Armada
370/XP/375/38x specific files only when CONFIG_MACH_MVEBU_V7 is
enabled.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1398709239-6126-1-git-send-email-thomas.petazzoni@free-electrons.comAcked-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

The cpu idle support will need to access to Power Management Service
Unit. This commit adds the architecture related functions that will be
used in the idle path of the cpuidle driver.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-9-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

This commit adds a function which adjusts the PMSU configuration to
automatically power down the L2 and coherency fabric when we enter a
certain idle state.

This feature is part of the Power Management Service Unit of the
Armada 370 and Armada XP SoCs.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-8-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

When going to deep idle we need to disable the SoC snooping (aka
hardware coherency support). Playing with the coherency fabric
requires to use assembly code to be sure that the compiler doesn't
reorder the instructions nor do wrong optimization.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-7-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Actually enabling coherency and adding a CPU on a SMP group are two
different operations which can be done separately. This patch splits
this in two functions.

Moreover as they use common pattern, this patch also creates local low
level functions (ll_get_coherency_base and ll_get_cpuid) to be used by
the exposed functions (ll_add_cpu_to_smp_group and
ll_enable_coherency)
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-6-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

set_cpu_coherent() took the SMP group ID as parameter. But this
parameter was never used, and the CPU always uses the SMP group 0. So
we can remove this parameter.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-5-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

ll_set_cpu_coherent is always used on the current CPU, so instead of
passing the CPU id as argument, ll_set_cpu_coherent() can find it by
itself.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-4-git-send-email-gregory.clement@free-electrons.comAcked-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

In order to be able to deal with the MMU enabled and the MMU disabled
cases, the base address of the coherency registers was passed to the
function. The address by itself was not interesting as it can't change
for a given SoC, the only thing we need is to have a distinction
between the physical or the virtual address.

This patch add a check of the MMU bit to choose the accurate address,
then the calling function doesn't have to pass this information.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397488214-20685-3-git-send-email-gregory.clement@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Since the Armada 38x PMSU registers are slightly different than the
Armada 370/XP PMSU ones, we introduce a new compatible string
"armada-380-pmsu" in the PMSU driver. These differences are not
visible for the current usage of the PMSU, but they might become
visible in the future.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-8-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Due to internal bootrom issue, CPU[1] initial jump code (four
instructions) should be placed in SRAM memory of the SoC. In order to
achieve this, we have to unmap the BootROM and at some specific
location where the BootROM was place, create a specific MBus window
for the SRAM. This SRAM is initialized with a few instructions of code
that allows to jump into the real secondary CPU boot address.

This workaround will most likely be disabled when newer steppings of
the Armada 375 will be made available, in which case a dynamic test
based on mvebu-soc-id will be added.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-10-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-10-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

This commit adds the SMP support for Armada 375 and Armada 38x. It
turns out that the SMP logic for both of these SOCs are fairly
similar, the only differences being:

 * A different method to set the secondary CPU boot address

 * An Armada 375 specific workaround needed for the early Z1 stepping,
   added by the following patch.

Other than that, the patch is fairly straightforward and adds the
usual platsmp and headsmp code, defining the smp_operations structure
that is referenced from the DT_MACHINE structures.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-9-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-9-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

In order to boot the secondary CPUs on Armada 375, we need to set the
boot address of these CPUs, through a register part of the System
Controller (this deviates from the Armada XP design, where the boot
address was defined using a register part of the PMSU unit).

Therefore, this commit adds a new helper function in the System
Controller driver to set the secondary CPU boot address.

Moreover, it moves the System Controller initialization as an
early_initcall(), since arch_initcall() is too late for an SMP-related
initialization.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-7-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-7-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

This commit adds the CPU_METHOD_OF_DECLARE declaration for the Armada
XP SMP operations. Note that the .smp_ops field of Armada XP
DT_MACHINE structure is kept, in order to ensure we remain compatible
with older Device Trees that do not include the "enable-method"
property for the CPUs.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-3-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The pmsu.c driver contained an armada_xp_boot_cpu() function that sets
the boot address of a secondary CPUs and deasserts the reset. However,
the Armada 375 needs a slightly different logic, so it makes more
sense to move this code into the Armada XP specific platsmp.c.

In order to achieve this, the mvebu_pmsu_set_cpu_boot_addr() function
is exported. It will be needed for both the Armada XP and Armada 38x
SMP implementations.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-2-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Non-DT irq handlers were working through irq causes from most-significant
to least-significant bit, while DT irqchip driver does it the other way
round. This revealed some more HW issues on Kirkwood peripheral IP, where
spurious sdio irqs can happen although irqs are masked.

Also, the generated binaries show that original non-DT order compared
to DT order save two instructions for each bit count check:

irqchip DT order with ffs():
  60:   e3a06001        mov     r6, #1
  64:   e2643000        rsb     r3, r4, #0
  68:   e0033004        and     r3, r3, r4
  6c:   e16f3f13        clz     r3, r3
  70:   e263301f        rsb     r3, r3, #31
  74:   e1c44316        bic     r4, r4, r6, lsl r3
  78:   e5971004        ldr     r1, [r7, #4]

Original non-DT order with fls():
  60:   e3a07001        mov     r7, #1
  64:   e16f3f14        clz     r3, r4
  68:   e263301f        rsb     r3, r3, #31
  6c:   e1c44317        bic     r4, r4, r7, lsl r3
  70:   e5951004        ldr     r1, [r5, #4]

Therefore, reverse irq bit handling back to original order by replacing
ffs() with fls().
Signed-off-by: NSebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Link: https://lkml.kernel.org/r/1398719528-23607-1-git-send-email-sebastian.hesselbarth@gmail.comAcked-by: NJason Cooper <jason@lakedaemon.net>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

Some irqchip initialization must be done on secondary CPUs. On mvebu
platforms, this is currently achieved by having the
arch/arm/mach-mvebu/platsmp.c code directly call into a function
exported by the irqchip driver, which isn't really nice.

This commit changes this by using the same solution as the one used in
the GIC driver: the irqchip driver registers a CPU notifier, which is
used to do the secondary CPU IRQ initialization. This way, the irqchip
driver is completely autonomous, and the function no longer needs to
be exposed from the irqchip driver to the SoC code.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-6-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Instead of having the SoC code in arch/arm/mach-mvebu/platsmp.c do the
set_smp_cross_call() to register the IPI-triggering function, it makes
more sense to do exactly what the GIC driver is doing: let the irqchip
driver do it. This way, it avoids having to expose the
armada_mpic_send_doorbell() function between the irqchip driver and
the SoC code.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-5-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Setting the start (or boot) address of a CPU is no more used only
during SMP bring up on Armada 370/XP, but it will also be used by the
CPU idle function of Armada XP, and by the Armada 38x SMP support.

Therefore this commit creates a separate PMSU function to set the boot
address of a CPU with the PMSU.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-7-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-7-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The initial binding for PMSU was wrong, as it didn't take into account
all the registers from the PMSU and moreover it referred to the CPU
reset registers which are not part of PMSU.

The Power Management Unit Service block also controls the Coherency
Fabric subsystem. These registers are needed for the CPU idle
implementation for the Armada 370/XP, it allows to enter a deep CPU
idle state where the Coherency Fabric and the L2 cache are powered
down.

This commit adds support for a new compatible for the PMSU node which
includes the registers related to the coherency fabric. It also keeps
compatibility with the old compatible string.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-5-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-5-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Until now, the PMSU driver was using of_iomap() to map its registers,
but of_iomap() doesn't call request_mem_region(). This commit fixes
the memory mapping code of the PMSU to do so, which will also be
useful for a later commit since we will need to adjust the resource
base address and size for Device Tree backward compatibility.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-4-git-send-email-thomas.petazzoni@free-electrons.comAcked-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

This commit changes the PMSU driver to no longer map itself the CPU
reset registers, and instead call into the CPU reset driver to
deassert the secondary CPUs for SMP booting.

In order to provide Device Tree backward compatibility, the CPU reset
driver is extended to not only support its official compatible string
"marvell,armada-370-cpu-reset", but to also look at the PMSU
compatible string "marvell,armada-370-xp-pmsu" to find the CPU reset
registers address. This allows old Device Tree to work correctly with
newer kernel versions. Therefore, the CPU reset driver implements the
following logic:

 * If one of the normal compatible strings
   "marvell,armada-370-cpu-reset" is found, then we map its first
   memory resource as the CPU reset registers.

 * Otherwise, if none of the normal compatible strings have been
   found, we look for the "marvell,armada-370-xp-pmsu" compatible
   string, and we map the second memory as the CPU reset registers.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-3-git-send-email-thomas.petazzoni@free-electrons.comAcked-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

The Armada 370 and Armada XP have registers that allow to reset the
CPUs, which is particularly useful to take the secondary CPUs out of
reset in the context of the SMP support.

Unfortunately, an implementation mistake was originally made and the
support for these registers was integrated into the PMSU driver, which
is in fact completely unrelated. And it turns out that the Armada 375
has the same CPU reset registers, but does not have the PMSU
registers.

Therefore, this commit creates a small CPU reset driver. All it does
is provide a simple mvebu_cpu_reset_deassert() function that the SMP
support code can call to take secondary CPUs out of reset. As of this
commit, the driver isn't being used, it will be used through changes
in the following commits.

Note that we initially planned to use the 'reset controller'
framework, but it requires the addition of "resets" properties in the
Device Tree, which are causing too many problems if we want to keep
the Device Tree backward compatibility. Moreover, the 'reset
controller' framework is mainly useful when a device driver needs to
request a reset of its device from a separate reset controller. In our
case, the CPU reset handling and the SMP core code are both located in
arch/arm/mach-mvebu/ and are tightly linked together, so there's no
real benefit in going through a separate framework.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-2-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The Armada 38x has a coherency unit that is similar to the one of the
Armada 375 SoC, except that it does not have the bug of the Armada 375
coherency unit that requires the XOR based workaround.

This commit therefore extends the Marvell EBU coherency code with a
new compatible string to support the Armada 38x coherency unit.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-9-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The early revisions of Armada 375 SOCs (Z1 stepping) have a bug in the
I/O coherency unit that prevents using the normal method for the I/O
coherency barrier. The recommended workaround is to use a XOR memset
transfer to act as the I/O coherency barrier.

This involves "borrowing" a XOR engine, which gets disabled in the
Device Tree so the normal XOR driver doesn't use it.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-8-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The Armada 375, like the Armada 370 and Armada XP, has a coherency
unit. However, unlike the coherency unit of 370/XP which does both CPU
and I/O coherency, the one on Armada 735 only does I/O
coherency. Therefore, instead of having two sets of registers (the
first one being used mainly to register each CPU in the coherency
fabric, the second one being used for the I/O coherency barrier), it
has only one set of register (for the I/O coherency barrier).

This commit adds a new "marvell,armada-375-coherency-fabric"
compatible string for this variant of the coherency fabric. The custom
DMA operations, and the way of triggering an I/O barrier is the same
as Armada 370/XP, so the code changes are minimal. However, the
set_cpu_coherent() function is not needed on Armada 375 and will not
work.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-7-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Contrary to the Armada 370 and XP that used the PJ4B Marvell cores,
the Armada 375 and Armada 38x use the ARM Cortex-A9. A consequence of
this is that the unit responsible for the coherency between CPUs is
now the ARM SCU, and not the Marvell coherency unit (which is still
present to do coherency with I/O devices).

Therefore this commit:

 * Ensures that the selection of the Armada 375 or Armada 38x SoC
   support enables the ARM SCU support in the kernel.

 * Make sure to initialize the SCU at boot time.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-6-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

In the mach-mvebu coherency code, instead of using
of_find_matching_node() and then of_match_node(), directly use the
of_find_matching_node_and_match() which does both at once.

We take this opportunity to also simplify the initialization of the
"type" variable.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-5-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Until now, the mvebu-mbus was guessing by itself whether hardware I/O
coherency was available or not by poking into the Device Tree to see
if the coherency fabric Device Tree node was present or not.

However, on some upcoming SoCs, the presence or absence of the
coherency fabric DT node isn't sufficient: in CONFIG_SMP, the
coherency can be enabled, but not in !CONFIG_SMP.

In order to clean this up, the mvebu_mbus_dt_init() function is
extended to get a boolean argument telling whether coherency is
enabled or not. Therefore, the logic to decide whether coherency is
available or not now belongs to the core SoC code instead of the
mvebu-mbus driver itself, which is much better.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-4-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

This commit extends the coherency fabric code to provide a
coherency_available()function that the SoC code can call to be told
whether coherency support is available or not. On Armada 370/XP,
coherency support is available as soon as the relevant DT node is
present. On some upcoming SoCs, the DT node needs to be present *and*
the system running with CONFIG_SMP enabled.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-3-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

The code that handles the coherency fabric of Armada 370 and Armada XP
in arch/arm/mach-mvebu/coherency.c made the assumption that there was
only one type of coherency fabric. Unfortunately, it turns out that
upcoming SoCs have a slightly different coherency unit.

In preparation to the introduction of the coherency support for more
SoCs, this commit:

 * Introduces a data associated to the compatible string in the
   compatible string match table, so that the code can differantiate
   the variant of coherency unit being used.

 * Separates the coherency unit initialization code into its own
   function.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-2-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Add the SoC Family, device ID and revision to /sys/bus/soc.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Link: https://lkml.kernel.org/r/1393955507-26436-1-git-send-email-andrew@lunn.chSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Some versions of gcc even warn about it:

  mm/shmem.c: In function ‘shmem_file_aio_read’:
  mm/shmem.c:1414: warning: ‘error’ may be used uninitialized in this function

If the loop is aborted during the first iteration by one of the two
first break statements, error will be uninitialized.

Introduced by commit 6e58e79d ("introduce copy_page_to_iter, kill
loop over iovec in generic_file_aio_read()").
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On 32 bit, size_t is "unsigned int", not "unsigned long", causing the
following warning when comparing with PAGE_SIZE, which is always "unsigned
long":

  fs/cifs/file.c: In function ‘cifs_readdata_to_iov’:
  fs/cifs/file.c:2757: warning: comparison of distinct pointer types lacks a cast

Introduced by commit 7f25bba8 ("cifs_iovec_read: keep iov_iter
between the calls of cifs_readdata_to_iov()"), which changed the
signedness of "remaining" and the code from min_t() to min().
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>