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gpu: nvgpu: fix pmu->mscg_stat optimization issue

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- with help of WRITE_ONCE() & ACCESS_ONCE()
  make sure variable pmu->mscg_stat read/write goes through
  without optimization
- Added WRITE_ONCE() define for kernel-3.18 version & below
  to support backward compatibility

issue: inconsistencies on getting MSCG to trigger consistently in P5
due to a lack of memory barrier around and volatile accesses to the
variable pmu->mscg_stat

JIRA DNVGPU-71

Change-Id: I04d30493d42c52710304dbdfb9cb4a1e9a76f2c0
Signed-off-by: Mahantesh Kumbar <mkumbar@nvidia.com>
Reviewed-on: http://git-master/r/1252524
(cherry picked from commit 8af7fc68e7ab06a856ba4ef4e44de7336682361b)
Reviewed-on: http://git-master/r/1271614
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
This commit is contained in:
Mahantesh Kumbar
2016-11-14 11:27:38 +05:30
committed by mobile promotions
parent 157ff622f3
commit efe0758081
4 changed files with 29 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/gpu/nvgpu/gk20a/gk20a.h
View File

@@ -64,6 +64,10 @@ struct acr_desc;
#endif
#include "gm206/bios_gm206.h"
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 18, 0)
#define WRITE_ONCE(x, val) \
x = val
#endif
/* PTIMER_REF_FREQ_HZ corresponds to a period of 32 nanoseconds.
32 ns is the resolution of ptimer. */

12
drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c
View File

@@ -511,15 +511,21 @@ static ssize_t mscg_enable_store(struct device *dev,
g->mscg_enabled = true;
if (g->ops.pmu.pmu_is_lpwr_feature_supported(g,
PMU_PG_LPWR_FEATURE_MSCG)) {
if (!pmu->mscg_stat)
pmu->mscg_stat = PMU_MSCG_ENABLED;
if (!ACCESS_ONCE(pmu->mscg_stat)) {
WRITE_ONCE(pmu->mscg_stat,
PMU_MSCG_ENABLED);
/* make status visible */
smp_mb();
}
}
} else if (!val && g->mscg_enabled) {
if (g->ops.pmu.pmu_is_lpwr_feature_supported(g,
PMU_PG_LPWR_FEATURE_MSCG)) {
gk20a_pmu_pg_global_enable(g, false);
pmu->mscg_stat = PMU_MSCG_DISABLED;
WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_DISABLED);
/* make status visible */
smp_mb();
g->mscg_enabled = false;
if (g->elpg_enabled)
gk20a_pmu_pg_global_enable(g, true);

8
drivers/gpu/nvgpu/gk20a/pmu_gk20a.c
View File

@@ -3388,7 +3388,9 @@ static void pmu_handle_pg_elpg_msg(struct gk20a *g, struct pmu_msg *msg,
PMU_PG_FEATURE_GR_POWER_GATING_ENABLED) {
pmu->initialized = true;
pmu->pmu_state = PMU_STATE_STARTED;
pmu->mscg_stat = PMU_MSCG_DISABLED;
WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_DISABLED);
/* make status visible */
smp_mb();
} else {
pmu->pmu_state = PMU_STATE_ELPG_BOOTED;
schedule_work(&pmu->pg_init);
@@ -4849,7 +4851,7 @@ int gk20a_pmu_enable_elpg(struct gk20a *g)
pg_engine_id++) {
if (pg_engine_id == PMU_PG_ELPG_ENGINE_ID_MS &&
pmu->mscg_stat == PMU_MSCG_DISABLED)
ACCESS_ONCE(pmu->mscg_stat) == PMU_MSCG_DISABLED)
continue;
if (BIT(pg_engine_id) & pg_engine_id_list)
@@ -4925,7 +4927,7 @@ int gk20a_pmu_disable_elpg(struct gk20a *g)
pg_engine_id++) {
if (pg_engine_id == PMU_PG_ELPG_ENGINE_ID_MS &&
pmu->mscg_stat == PMU_MSCG_DISABLED)
ACCESS_ONCE(pmu->mscg_stat) == PMU_MSCG_DISABLED)
continue;
if (BIT(pg_engine_id) & pg_engine_id_list) {

16
drivers/gpu/nvgpu/lpwr/lpwr.c
View File

@@ -1,5 +1,5 @@
/*
* Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
* Copyright (c) 2016-2017, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
@@ -362,8 +362,11 @@ int nvgpu_lpwr_enable_pg(struct gk20a *g, bool pstate_lock)
is_mscg_supported = nvgpu_lpwr_is_mscg_supported(g,
present_pstate);
if (is_mscg_supported && g->mscg_enabled) {
if (!pmu->mscg_stat)
pmu->mscg_stat = PMU_MSCG_ENABLED;
if (!ACCESS_ONCE(pmu->mscg_stat)) {
WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_ENABLED);
/* make status visible */
smp_mb();
}
}
is_rppg_supported = nvgpu_lpwr_is_rppg_supported(g,
@@ -409,8 +412,11 @@ int nvgpu_lpwr_disable_pg(struct gk20a *g, bool pstate_lock)
is_mscg_supported = nvgpu_lpwr_is_mscg_supported(g,
present_pstate);
if (is_mscg_supported && g->mscg_enabled) {
if (pmu->mscg_stat)
pmu->mscg_stat = PMU_MSCG_DISABLED;
if (ACCESS_ONCE(pmu->mscg_stat)) {
WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_DISABLED);
/* make status visible */
smp_mb();
}
}
exit_unlock: