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Conor Dooley 9decec2993 Revert "clocksource/drivers/riscv: Events are stopped during CPU suspend"
[ Upstream commit d9f15a9de44affe733e34f93bc184945ba277e6d ]

This reverts commit 232ccac1bd9b5bfe73895f527c08623e7fa0752d.

On the subject of suspend, the RISC-V SBI spec states:

  This does not cover whether any given events actually reach the hart or
  not, just what the hart will do if it receives an event. On PolarFire
  SoC, and potentially other SiFive based implementations, events from the
  RISC-V timer do reach a hart during suspend. This is not the case for the
  implementation on the Allwinner D1 - there timer events are not received
  during suspend.

To fix this, the CLOCK_EVT_FEAT_C3STOP (mis)feature was enabled for the
timer driver - but this has broken both RCU stall detection and timers
generally on PolarFire SoC and potentially other SiFive based
implementations.

If an AXI read to the PCIe controller on PolarFire SoC times out, the
system will stall, however, with CLOCK_EVT_FEAT_C3STOP active, the system
just locks up without RCU stalling:

	io scheduler mq-deadline registered
	io scheduler kyber registered
	microchip-pcie 2000000000.pcie: host bridge /soc/pcie@2000000000 ranges:
	microchip-pcie 2000000000.pcie:      MEM 0x2008000000..0x2087ffffff -> 0x0008000000
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: axi read request error
	microchip-pcie 2000000000.pcie: axi read timeout
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: sec error in pcie2axi buffer
	microchip-pcie 2000000000.pcie: ded error in pcie2axi buffer
	Freeing initrd memory: 7332K

Similarly issues were reported with clock_nanosleep() - with a test app
that sleeps each cpu for 6, 5, 4, 3 ms respectively, HZ=250 & the blamed
commit in place, the sleep times are rounded up to the next jiffy:

== CPU: 1 ==      == CPU: 2 ==      == CPU: 3 ==      == CPU: 4 ==
Mean: 7.974992    Mean: 7.976534    Mean: 7.962591    Mean: 3.952179
Std Dev: 0.154374 Std Dev: 0.156082 Std Dev: 0.171018 Std Dev: 0.076193
Hi: 9.472000      Hi: 10.495000     Hi: 8.864000      Hi: 4.736000
Lo: 6.087000      Lo: 6.380000      Lo: 4.872000      Lo: 3.403000
Samples: 521      Samples: 521      Samples: 521      Samples: 521

Fortunately, the D1 has a second timer, which is "currently used in
preference to the RISC-V/SBI timer driver" so a revert here does not
hurt operation of D1 in its current form.

Ultimately, a DeviceTree property (or node) will be added to encode the
behaviour of the timers, but until then revert the addition of
CLOCK_EVT_FEAT_C3STOP.

Fixes: 232ccac1bd9b ("clocksource/drivers/riscv: Events are stopped during CPU suspend")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/linux-riscv/YzYTNQRxLr7Q9JR0@spud/
Link: https://github.com/riscv-non-isa/riscv-sbi-doc/issues/98/
Link: https://lore.kernel.org/linux-riscv/bf6d3b1f-f703-4a25-833e-972a44a04114@sholland.org/
Link: https://lore.kernel.org/r/20221122121620.3522431-1-conor.dooley@microchip.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-08 11:23:06 +01:00
arch x86/ioremap: Fix page aligned size calculation in __ioremap_caller() 2022-12-08 11:23:06 +01:00
block block, bfq: fix null pointer dereference in bfq_bio_bfqg() 2022-12-08 11:22:57 +01:00
certs
crypto
Documentation docs: update mediator contact information in CoC doc 2022-11-25 17:42:20 +01:00
drivers Revert "clocksource/drivers/riscv: Events are stopped during CPU suspend" 2022-12-08 11:23:06 +01:00
fs epoll: check for events when removing a timed out thread from the wait queue 2022-12-08 11:23:05 +01:00
include tracing/ring-buffer: Have polling block on watermark 2022-12-08 11:23:05 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc
kernel tracing/ring-buffer: Have polling block on watermark 2022-12-08 11:23:05 +01:00
lib Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled 2022-12-08 11:23:05 +01:00
LICENSES
mm mm: fs: initialize fsdata passed to write_begin/write_end interface 2022-11-25 17:42:22 +01:00
net Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM 2022-12-08 11:23:05 +01:00
samples
scripts scripts/faddr2line: Fix regression in name resolution on ppc64le 2022-12-08 11:23:02 +01:00
security
sound ASoC: ops: Fix bounds check for _sx controls 2022-12-08 11:23:04 +01:00
tools ipv4: Fix route deletion when nexthop info is not specified 2022-12-08 11:23:05 +01:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.225 2022-11-25 17:42:22 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.