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| author | Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> | 2018-02-23 19:41:52 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2018-02-28 10:45:31 -0800 |
| commit | 07423d00a2b2a71a97e4287d9262cb83c4c4c89f (patch) | |
| tree | 5c9e8d5cd23e09041229d5dea96c3f82a5530bfa /include | |
| parent | 701eda01cbd212bae2f7d29cf14322bd49b94657 (diff) | |
| download | linux-07423d00a2b2a71a97e4287d9262cb83c4c4c89f.tar.bz2 | |
ARC: mcip: halt GFRC counter when ARC cores halt
In SMP systems, GFRC is used for clocksource. However by default the
counter keeps running even when core is halted (say when debugging via a
JTAG debugger). This confuses Linux timekeeping and triggers flase RCU stall
splat such as below:
| [ARCLinux]# while true; do ./shm_open_23-1.run-test ; done
| Running with 1000 processes for 1000 objects
| hrtimer: interrupt took 485060 ns
|
| create_cnt: 1000
| Running with 1000 processes for 1000 objects
| [ARCLinux]# INFO: rcu_preempt self-detected stall on CPU
| 2-...: (1 GPs behind) idle=a01/1/0 softirq=135770/135773 fqs=0
| INFO: rcu_preempt detected stalls on CPUs/tasks:
| 0-...: (1 GPs behind) idle=71e/0/0 softirq=135264/135264 fqs=0
| 2-...: (1 GPs behind) idle=a01/1/0 softirq=135770/135773 fqs=0
| 3-...: (1 GPs behind) idle=4e0/0/0 softirq=134304/134304 fqs=0
| (detected by 1, t=13648 jiffies, g=31493, c=31492, q=1)
Starting from ARC HS v3.0 it's possible to tie GFRC to state of up-to 4
ARC cores with help of GFRC's CORE register where we set a mask for
cores which state we need to rely on.
We update cpu mask every time new cpu came online instead of using
hardcoded one or using mask generated from "possible_cpus" as we
want it set correctly even if we run kernel on HW which has fewer cores
than expected (or we launch kernel via debugger and kick fever cores
than HW has)
Note that GFRC halts when all cores have halted and thus relies on
programming of Inter-Core-dEbug register to halt all cores when one
halts.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: rewrote changelog]
Diffstat (limited to 'include')
| -rw-r--r-- | include/soc/arc/mcip.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/soc/arc/mcip.h b/include/soc/arc/mcip.h index c2d1b15da136..1138da57baaf 100644 --- a/include/soc/arc/mcip.h +++ b/include/soc/arc/mcip.h @@ -15,6 +15,7 @@ #define ARC_REG_MCIP_BCR 0x0d0 #define ARC_REG_MCIP_IDU_BCR 0x0D5 +#define ARC_REG_GFRC_BUILD 0x0D6 #define ARC_REG_MCIP_CMD 0x600 #define ARC_REG_MCIP_WDATA 0x601 #define ARC_REG_MCIP_READBACK 0x602 @@ -40,6 +41,8 @@ struct mcip_cmd { #define CMD_GFRC_READ_LO 0x42 #define CMD_GFRC_READ_HI 0x43 +#define CMD_GFRC_SET_CORE 0x47 +#define CMD_GFRC_READ_CORE 0x48 #define CMD_IDU_ENABLE 0x71 #define CMD_IDU_DISABLE 0x72 |