Pull ARC architecture updates from Vineet Gupta:
- support for HS38 cores based on ARCv2 ISA
ARCv2 is the next generation ISA from Synopsys and basis for the
HS3{4,6,8} families of processors which retain the traditional ARC mantra of
low power and configurability and are now more performant and feature rich.
HS38x is a 10 stage pipeline core which supports MMU (with huge pages) and
SMP (upto 4 cores) among other features.
+ www.synopsys.com/dw/ipdir.php?ds=arc-hs38-processor
+ http://news.synopsys.com/2014-10-14-New-DesignWare-ARC-HS38-Processor-Doubles-Performance-for-Embedded-Linux-Applications
+ http://www.embedded.com/electronics-news/4435975/Synopsys-ARC-HS38-core-gives-2X-boost-to-Linux-based-apps
- support for ARC SDP (Software Development platform): Main Board + CPU Cards
= AXS101: CPU Card with ARC700 in silicon @ 700 MHz
= AXS103: CPU Card with HS38x in FPGA
- refactoring of ARCompact port to accomodate new ARCv2 ISA
- misc updates/cleanups
* tag 'arc-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (72 commits)
ARC: Fix build failures for ARCompact in linux-next after ARCv2 support
ARCv2: Allow older gcc to cope with new regime of ARCv2/ARCompact support
ARCv2: [vdk] dts files and defconfig for HS38 VDK
ARCv2: [axs103] Support ARC SDP FPGA platform for HS38x cores
ARC: [axs101] Prepare for AXS103
ARCv2: [nsim*hs*] Support simulation platforms for HS38x cores
ARCv2: All bits in place, allow ARCv2 builds
ARCv2: SLC: Handle explcit flush for DMA ops (w/o IO-coherency)
ARCv2: STAR 9000837815 workaround hardware exclusive transactions livelock
ARC: Reduce bitops lines of code using macros
ARCv2: barriers
arch: conditionally define smp_{mb,rmb,wmb}
ARC: add smp barriers around atomics per Documentation/atomic_ops.txt
ARC: add compiler barrier to LLSC based cmpxchg
ARCv2: SMP: intc: IDU 2nd level intc for dynamic IRQ distribution
ARCv2: SMP: clocksource: Enable Global Real Time counter
ARCv2: SMP: ARConnect debug/robustness
ARCv2: SMP: Support ARConnect (MCIP) for Inter-Core-Interrupts et al
ARC: make plat_smp_ops weak to allow over-rides
ARCv2: clocksource: Introduce 64bit local RTC counter
...
Pull asm/scatterlist.h removal from Jens Axboe:
"We don't have any specific arch scatterlist anymore, since parisc
finally switched over. Kill the include"
* 'for-4.2/sg' of git://git.kernel.dk/linux-block:
remove scatterlist.h generation from arch Kbuild files
remove <asm/scatterlist.h>
Pull Renesas H8/300 architecture re-introduction from Yoshinori Sato.
We dropped arch/h8300 two years ago as stale and old, this is a new and
more modern rewritten arch support for the same architecture.
* tag 'for-4.2' of git://git.sourceforge.jp/gitroot/uclinux-h8/linux: (27 commits)
h8300: fix typo.
h8300: Always build dtb
h8300: Remove ARCH_WANT_IPC_PARSE_VERSION
sh-sci: Get register size from platform device
clk: h8300: fix error handling in h8s2678_pll_clk_setup()
h8300: Symbol name fix
h8300: devicetree source
h8300: configs
h8300: IRQ chip driver
h8300: clocksource
h8300: clock driver
h8300: Build scripts
h8300: library functions
h8300: Memory management
h8300: miscellaneous functions
h8300: process helpers
h8300: compressed image support
h8300: Low level entry
h8300: kernel startup
h8300: Interrupt and exceptions
...
Architectures like ppc64 [1] need to do special things while clearing pmd
before a collapse. For them this operation is largely different from a
normal hugepage pte clear. Hence add a separate function to clear pmd
before collapse. After this patch pmdp_* functions operate only on
hugepage pte, and not on regular pmd_t values pointing to page table.
[1] ppc64 needs to invalidate all the normal page pte mappings we already
have inserted in the hardware hash page table. But before doing that we
need to make sure there are no parallel hash page table insert going on.
So we need to do a kick_all_cpus_sync() before flushing the older hash
table entries. By moving this to a separate function we capture these
details and mention how it is different from a hugepage pte clear.
This patch is a cleanup and only does code movement for clarity. There
should not be any change in functionality.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
That way arches can define the minimal versions and still #include
asm-generic for defaults (vs. defining defaults in arch code)
See new barrier.h in arc for usage !
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Pull PCI updates from Bjorn Helgaas:
"PCI changes for the v4.2 merge window:
Enumeration
- Move pci_ari_enabled() to global header (Alex Williamson)
- Account for ARI in _PRT lookups (Alex Williamson)
- Remove unused pci_scan_bus_parented() (Yijing Wang)
Resource management
- Use host bridge _CRS info on systems with >32 bit addressing (Bjorn Helgaas)
- Use host bridge _CRS info on Foxconn K8M890-8237A (Bjorn Helgaas)
- Fix pci_address_to_pio() conversion of CPU address to I/O port (Zhichang Yuan)
- Add pci_bus_addr_t (Yinghai Lu)
PCI device hotplug
- Wait for pciehp command completion where necessary (Alex Williamson)
- Drop pointless ACPI-based "slot detection" check (Rafael J. Wysocki)
- Check ignore_hotplug for all downstream devices (Rafael J. Wysocki)
- Propagate the "ignore hotplug" setting to parent (Rafael J. Wysocki)
- Inline pciehp "handle event" functions into the ISR (Bjorn Helgaas)
- Clean up pciehp debug logging (Bjorn Helgaas)
Power management
- Remove redundant PCIe port type checking (Yijing Wang)
- Add dev->has_secondary_link to track downstream PCIe links (Yijing Wang)
- Use dev->has_secondary_link to find downstream links for ASPM (Yijing Wang)
- Drop __pci_disable_link_state() useless "force" parameter (Bjorn Helgaas)
- Simplify Clock Power Management setting (Bjorn Helgaas)
Virtualization
- Add ACS quirks for Intel 9-series PCH root ports (Alex Williamson)
- Add function 1 DMA alias quirk for Marvell 9120 (Sakari Ailus)
MSI
- Disable MSI at enumeration even if kernel doesn't support MSI (Michael S. Tsirkin)
- Remove unused pci_msi_off() (Bjorn Helgaas)
- Rename msi_set_enable(), msix_clear_and_set_ctrl() (Michael S. Tsirkin)
- Export pci_msi_set_enable(), pci_msix_clear_and_set_ctrl() (Michael S. Tsirkin)
- Drop pci_msi_off() calls during probe (Michael S. Tsirkin)
APM X-Gene host bridge driver
- Add APM X-Gene v1 PCIe MSI/MSIX termination driver (Duc Dang)
- Add APM X-Gene PCIe MSI DTS nodes (Duc Dang)
- Disable Configuration Request Retry Status for v1 silicon (Duc Dang)
- Allow config access to Root Port even when link is down (Duc Dang)
Broadcom iProc host bridge driver
- Allow override of device tree IRQ mapping function (Hauke Mehrtens)
- Add BCMA PCIe driver (Hauke Mehrtens)
- Directly add PCI resources (Hauke Mehrtens)
- Free resource list after registration (Hauke Mehrtens)
Freescale i.MX6 host bridge driver
- Add speed change timeout message (Troy Kisky)
- Rename imx6_pcie_start_link() to imx6_pcie_establish_link() (Bjorn Helgaas)
Freescale Layerscape host bridge driver
- Use dw_pcie_link_up() consistently (Bjorn Helgaas)
- Factor out ls_pcie_establish_link() (Bjorn Helgaas)
Marvell MVEBU host bridge driver
- Remove mvebu_pcie_scan_bus() (Yijing Wang)
NVIDIA Tegra host bridge driver
- Remove tegra_pcie_scan_bus() (Yijing Wang)
Synopsys DesignWare host bridge driver
- Consolidate outbound iATU programming functions (Jisheng Zhang)
- Use iATU0 for cfg and IO, iATU1 for MEM (Jisheng Zhang)
- Add support for x8 links (Zhou Wang)
- Wait for link to come up with consistent style (Bjorn Helgaas)
- Use pci_scan_root_bus() for simplicity (Yijing Wang)
TI DRA7xx host bridge driver
- Use dw_pcie_link_up() consistently (Bjorn Helgaas)
Miscellaneous
- Include <linux/pci.h>, not <asm/pci.h> (Bjorn Helgaas)
- Remove unnecessary #includes of <asm/pci.h> (Bjorn Helgaas)
- Remove unused pcibios_select_root() (again) (Bjorn Helgaas)
- Remove unused pci_dma_burst_advice() (Bjorn Helgaas)
- xen/pcifront: Don't use deprecated function pci_scan_bus_parented() (Arnd Bergmann)"
* tag 'pci-v4.2-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (58 commits)
PCI: pciehp: Inline the "handle event" functions into the ISR
PCI: pciehp: Rename queue_interrupt_event() to pciehp_queue_interrupt_event()
PCI: pciehp: Make queue_interrupt_event() void
PCI: xgene: Allow config access to Root Port even when link is down
PCI: xgene: Disable Configuration Request Retry Status for v1 silicon
PCI: pciehp: Clean up debug logging
x86/PCI: Use host bridge _CRS info on systems with >32 bit addressing
PCI: imx6: Add #define PCIE_RC_LCSR
PCI: imx6: Use "u32", not "uint32_t"
PCI: Remove unused pci_scan_bus_parented()
xen/pcifront: Don't use deprecated function pci_scan_bus_parented()
PCI: imx6: Add speed change timeout message
PCI/ASPM: Simplify Clock Power Management setting
PCI: designware: Wait for link to come up with consistent style
PCI: layerscape: Factor out ls_pcie_establish_link()
PCI: layerscape: Use dw_pcie_link_up() consistently
PCI: dra7xx: Use dw_pcie_link_up() consistently
x86/PCI: Use host bridge _CRS info on Foxconn K8M890-8237A
PCI: pciehp: Wait for hotplug command completion where necessary
PCI: Remove unused pci_dma_burst_advice()
...
Pull gpio updates from Linus Walleij:
"This is the big bulk of GPIO changes queued for the v4.2 kernel
series:
- a big set of cleanups to the aged sysfs interface from Johan
Hovold. To get these in, v4.1-rc3 was merged into the tree as the
first patch in that series had to go into stable. This makes the
locking much more fine-grained (get rid of the "big GPIO lock(s)"
and store states in the GPIO descriptors.
- rename gpiod_[g|s]et_array() to gpiod_[g|s]et_array_value() to
avoid confusions.
- New drivers for:
* NXP LPC18xx (currently LPC1850)
* NetLogic XLP
* Broadcom STB SoC's
* Axis ETRAXFS
* Zynq Ultrascale+ (subdriver)
- ACPI:
* make it possible to retrieve GpioInt resources from a GPIO
device using acpi_dev_gpio_irq_get()
* merge some dependent I2C changes exploiting this.
* support the ARM X-Gene GPIO standby driver.
- make it possible for the generic GPIO driver to read back the value
set registers to reflect current status.
- loads of OMAP IRQ handling fixes.
- incremental improvements to Kona, max732x, OMAP, MXC, RCAR,
PCA953x, STP-XWAY, PCF857x, Crystalcove, TB10x.
- janitorial (constification, checkpatch cleanups)"
* tag 'gpio-v4.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (71 commits)
gpio: Fix checkpatch.pl issues
gpio: pcf857x: handle only enabled irqs
gpio / ACPI: Return -EPROBE_DEFER if the gpiochip was not found
GPIO / ACPI: export acpi_gpiochip_request(free)_interrupts for module use
gpio: improve error reporting on own descriptors
gpio: promote own request failure to pr_err()
gpio: Added support to Zynq Ultrascale+ MPSoC
gpio: add ETRAXFS GPIO driver
fix documentation after renaming gpiod_set_array to gpiod_set_array_value
gpio: Add GPIO support for Broadcom STB SoCs
gpio: xgene: add ACPI support for APM X-Gene GPIO standby driver
gpio: tb10x: Drop unneeded free_irq() call
gpio: crystalcove: set IRQCHIP_SKIP_SET_WAKE for the irqchip
gpio: stp-xway: Use the of_property_read_u32 helper
gpio: pcf857x: Check for irq_set_irq_wake() failures
gpio-stp-xway: Fix enabling the highest bit of the PHY LEDs
gpio: Prevent an integer overflow in the pca953x driver
gpio: omap: rework omap_gpio_irq_startup to handle current pin state properly
gpio: omap: rework omap_gpio_request to touch only gpio specific registers
gpio: omap: rework omap_x_irq_shutdown to touch only irqs specific registers
...
All architecture use same asm-offsets.h
So it generic header.
Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Pull x86 core updates from Ingo Molnar:
"There were so many changes in the x86/asm, x86/apic and x86/mm topics
in this cycle that the topical separation of -tip broke down somewhat -
so the result is a more traditional architecture pull request,
collected into the 'x86/core' topic.
The topics were still maintained separately as far as possible, so
bisectability and conceptual separation should still be pretty good -
but there were a handful of merge points to avoid excessive
dependencies (and conflicts) that would have been poorly tested in the
end.
The next cycle will hopefully be much more quiet (or at least will
have fewer dependencies).
The main changes in this cycle were:
* x86/apic changes, with related IRQ core changes: (Jiang Liu, Thomas
Gleixner)
- This is the second and most intrusive part of changes to the x86
interrupt handling - full conversion to hierarchical interrupt
domains:
[IOAPIC domain] -----
|
[MSI domain] --------[Remapping domain] ----- [ Vector domain ]
| (optional) |
[HPET MSI domain] ----- |
|
[DMAR domain] -----------------------------
|
[Legacy domain] -----------------------------
This now reflects the actual hardware and allowed us to distangle
the domain specific code from the underlying parent domain, which
can be optional in the case of interrupt remapping. It's a clear
separation of functionality and removes quite some duct tape
constructs which plugged the remap code between ioapic/msi/hpet
and the vector management.
- Intel IOMMU IRQ remapping enhancements, to allow direct interrupt
injection into guests (Feng Wu)
* x86/asm changes:
- Tons of cleanups and small speedups, micro-optimizations. This
is in preparation to move a good chunk of the low level entry
code from assembly to C code (Denys Vlasenko, Andy Lutomirski,
Brian Gerst)
- Moved all system entry related code to a new home under
arch/x86/entry/ (Ingo Molnar)
- Removal of the fragile and ugly CFI dwarf debuginfo annotations.
Conversion to C will reintroduce many of them - but meanwhile
they are only getting in the way, and the upstream kernel does
not rely on them (Ingo Molnar)
- NOP handling refinements. (Borislav Petkov)
* x86/mm changes:
- Big PAT and MTRR rework: making the code more robust and
preparing to phase out exposing direct MTRR interfaces to drivers -
in favor of using PAT driven interfaces (Toshi Kani, Luis R
Rodriguez, Borislav Petkov)
- New ioremap_wt()/set_memory_wt() interfaces to support
Write-Through cached memory mappings. This is especially
important for good performance on NVDIMM hardware (Toshi Kani)
* x86/ras changes:
- Add support for deferred errors on AMD (Aravind Gopalakrishnan)
This is an important RAS feature which adds hardware support for
poisoned data. That means roughly that the hardware marks data
which it has detected as corrupted but wasn't able to correct, as
poisoned data and raises an APIC interrupt to signal that in the
form of a deferred error. It is the OS's responsibility then to
take proper recovery action and thus prolonge system lifetime as
far as possible.
- Add support for Intel "Local MCE"s: upcoming CPUs will support
CPU-local MCE interrupts, as opposed to the traditional system-
wide broadcasted MCE interrupts (Ashok Raj)
- Misc cleanups (Borislav Petkov)
* x86/platform changes:
- Intel Atom SoC updates
... and lots of other cleanups, fixlets and other changes - see the
shortlog and the Git log for details"
* 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (222 commits)
x86/hpet: Use proper hpet device number for MSI allocation
x86/hpet: Check for irq==0 when allocating hpet MSI interrupts
x86/mm/pat, drivers/infiniband/ipath: Use arch_phys_wc_add() and require PAT disabled
x86/mm/pat, drivers/media/ivtv: Use arch_phys_wc_add() and require PAT disabled
x86/platform/intel/baytrail: Add comments about why we disabled HPET on Baytrail
genirq: Prevent crash in irq_move_irq()
genirq: Enhance irq_data_to_desc() to support hierarchy irqdomain
iommu, x86: Properly handle posted interrupts for IOMMU hotplug
iommu, x86: Provide irq_remapping_cap() interface
iommu, x86: Setup Posted-Interrupts capability for Intel iommu
iommu, x86: Add cap_pi_support() to detect VT-d PI capability
iommu, x86: Avoid migrating VT-d posted interrupts
iommu, x86: Save the mode (posted or remapped) of an IRTE
iommu, x86: Implement irq_set_vcpu_affinity for intel_ir_chip
iommu: dmar: Provide helper to copy shared irte fields
iommu: dmar: Extend struct irte for VT-d Posted-Interrupts
iommu: Add new member capability to struct irq_remap_ops
x86/asm/entry/64: Disentangle error_entry/exit gsbase/ebx/usermode code
x86/asm/entry/32: Shorten __audit_syscall_entry() args preparation
x86/asm/entry/32: Explain reloading of registers after __audit_syscall_entry()
...
Pull scheduler updates from Ingo Molnar:
"The main changes are:
- lockless wakeup support for futexes and IPC message queues
(Davidlohr Bueso, Peter Zijlstra)
- Replace spinlocks with atomics in thread_group_cputimer(), to
improve scalability (Jason Low)
- NUMA balancing improvements (Rik van Riel)
- SCHED_DEADLINE improvements (Wanpeng Li)
- clean up and reorganize preemption helpers (Frederic Weisbecker)
- decouple page fault disabling machinery from the preemption
counter, to improve debuggability and robustness (David
Hildenbrand)
- SCHED_DEADLINE documentation updates (Luca Abeni)
- topology CPU masks cleanups (Bartosz Golaszewski)
- /proc/sched_debug improvements (Srikar Dronamraju)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits)
sched/deadline: Remove needless parameter in dl_runtime_exceeded()
sched: Remove superfluous resetting of the p->dl_throttled flag
sched/deadline: Drop duplicate init_sched_dl_class() declaration
sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target
sched/deadline: Make init_sched_dl_class() __init
sched/deadline: Optimize pull_dl_task()
sched/preempt: Add static_key() to preempt_notifiers
sched/preempt: Fix preempt notifiers documentation about hlist_del() within unsafe iteration
sched/stop_machine: Fix deadlock between multiple stop_two_cpus()
sched/debug: Add sum_sleep_runtime to /proc/<pid>/sched
sched/debug: Replace vruntime with wait_sum in /proc/sched_debug
sched/debug: Properly format runnable tasks in /proc/sched_debug
sched/numa: Only consider less busy nodes as numa balancing destinations
Revert 095bebf61a ("sched/numa: Do not move past the balance point if unbalanced")
sched/fair: Prevent throttling in early pick_next_task_fair()
preempt: Reorganize the notrace definitions a bit
preempt: Use preempt_schedule_context() as the official tracing preemption point
sched: Make preempt_schedule_context() function-tracing safe
x86: Remove cpu_sibling_mask() and cpu_core_mask()
x86: Replace cpu_**_mask() with topology_**_cpumask()
...
The rtmutex code is the only user of __HAVE_ARCH_CMPXCHG and we have a few
other user of cmpxchg() which do not care about __HAVE_ARCH_CMPXCHG. This
define was first introduced in 23f78d4a0 ("[PATCH] pi-futex: rt mutex core")
which is v2.6.18. The generic cmpxchg was introduced later in 068fbad288
("Add cmpxchg_local to asm-generic for per cpu atomic operations") which is
v2.6.25.
Back then something was required to get rtmutex working with the fast
path on architectures without cmpxchg and this seems to be the result.
It popped up recently on rt-users because ARM (v6+) does not define
__HAVE_ARCH_CMPXCHG (even that it implements it) which results in slower
locking performance in the fast path.
To put some numbers on it: preempt -RT, am335x, 10 loops of
100000 invocations of rt_spin_lock() + rt_spin_unlock() (time "total" is
the average of the 10 loops for the 100000 invocations, "loop" is
"total / 100000 * 1000"):
cmpxchg | slowpath used || cmpxchg used
| total | loop || total | loop
--------|-----------|-------||------------|-------
ARMv6 | 9129.4 us | 91 ns || 3311.9 us | 33 ns
generic | 9360.2 us | 94 ns || 10834.6 us | 108 ns
----------------------------||--------------------
Forcing it to generic cmpxchg() made things worse for the slowpath and
even worse in cmpxchg() path. It boils down to 14ns more per lock+unlock
in a cache hot loop so it might not be that much in real world.
The last test was a substitute for pre ARMv6 machine but then I was able
to perform the comparison on imx28 which is ARMv5 and therefore is
always is using the generic cmpxchg implementation. And the numbers:
| total | loop
-------- |----------- |--------
slowpath | 263937.2 us | 2639 ns
cmpxchg | 16934.2 us | 169 ns
--------------------------------
The numbers are larger since the machine is slower in general. However,
letting rtmutex use cmpxchg() instead the slowpath seem to improve things.
Since from the ARM (tested on am335x + imx28) point of view always
using cmpxchg() in rt_mutex_lock() + rt_mutex_unlock() makes sense I
would drop the define.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: will.deacon@arm.com
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20150225175613.GE6823@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Remove gpiod_sysfs_set_active_low (and gpio_sysfs_set_active_low) which
allowed code to change the polarity of a gpio line even after it had
been exported through sysfs.
Drivers should not care, and generally does not know, about gpio-line
polarity which is a hardware feature that needs to be described by
firmware.
It is currently possible to define gpio-line polarity in device-tree and
acpi firmware or using platform data. Userspace can also change the
polarity through sysfs.
Note that drivers using the legacy gpio interface could still use
GPIOF_ACTIVE_LOW to change the polarity before exporting the gpio.
There are no in-kernel users of this interface.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Harry Wei <harryxiyou@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@zh-kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
ioremap_nocache() currently uses UC- by default. Our goal is to
eventually make UC the default. Linux maps UC- to PCD=1, PWT=0
page attributes on non-PAT systems. Linux maps UC to PCD=1,
PWT=1 page attributes on non-PAT systems. On non-PAT and PAT
systems a WC MTRR has different effects on pages with either of
these attributes. In order to help with a smooth transition its
best to enable use of UC (PCD,1, PWT=1) on a region as that
ensures a WC MTRR will have no effect on a region, this however
requires us to have an way to declare a region as UC and we
currently do not have a way to do this.
WC MTRR on non-PAT system with PCD=1, PWT=0 (UC-) yields WC.
WC MTRR on non-PAT system with PCD=1, PWT=1 (UC) yields UC.
WC MTRR on PAT system with PCD=1, PWT=0 (UC-) yields WC.
WC MTRR on PAT system with PCD=1, PWT=1 (UC) yields UC.
A flip of the default ioremap_nocache() behaviour from UC- to UC
can therefore regress a memory region from effective memory type
WC to UC if MTRRs are used. Use of MTRRs should be phased out
and in the best case only arch_phys_wc_add() use will remain,
even if this happens arch_phys_wc_add() will have an effect on
non-PAT systems and changes to default ioremap_nocache()
behaviour could regress drivers.
Now, ideally we'd use ioremap_nocache() on the regions in which
we'd need uncachable memory types and avoid any MTRRs on those
regions. There are however some restrictions on MTRRs use, such
as the requirement of having the base and size of variable sized
MTRRs to be powers of two, which could mean having to use a WC
MTRR over a large area which includes a region in which
write-combining effects are undesirable.
Add ioremap_uc() to help with the both phasing out of MTRR use
and also provide a way to blacklist small WC undesirable regions
in devices with mixed regions which are size-implicated to use
large WC MTRRs. Use of ioremap_uc() helps phase out MTRR use by
avoiding regressions with an eventual flip of default behaviour
or ioremap_nocache() from UC- to UC.
Drivers working with WC MTRRs can use the below table to review
and consider the use of ioremap*() and similar helpers to ensure
appropriate behaviour long term even if default
ioremap_nocache() behaviour changes from UC- to UC.
Although ioremap_uc() is being added we leave set_memory_uc() to
use UC- as only initial memory type setup is required to be able
to accommodate existing device drivers and phase out MTRR use.
It should also be clarified that set_memory_uc() cannot be used
with IO memory, even though its use will not return any errors,
it really has no effect.
----------------------------------------------------------------------
MTRR Non-PAT PAT Linux ioremap value Effective memory type
----------------------------------------------------------------------
Non-PAT | PAT
PAT
|PCD
||PWT
|||
WC 000 WB _PAGE_CACHE_MODE_WB WC | WC
WC 001 WC _PAGE_CACHE_MODE_WC WC* | WC
WC 010 UC- _PAGE_CACHE_MODE_UC_MINUS WC* | WC
WC 011 UC _PAGE_CACHE_MODE_UC UC | UC
----------------------------------------------------------------------
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Travis <travis@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Ville Syrjälä <syrjala@sci.fi>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-fbdev@vger.kernel.org
Link: http://lkml.kernel.org/r/1430343851-967-2-git-send-email-mcgrof@do-not-panic.com
Link: http://lkml.kernel.org/r/1431332153-18566-9-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linus Torvalds
Aneesh Kumar K.V
Vineet Gupta
Yoshinori Sato
Ingo Molnar
Bjorn Helgaas
Frederic Weisbecker
Toshi Kani
David Hildenbrand
Peter Zijlstra
Sebastian Andrzej Siewior
Johan Hovold
Luis R. Rodriguez