[PATCH 4/5] drm/i915: Introduce a non-blocking power domain for vblank interrupts
Dhinakaran Pandiyan
dhinakaran.pandiyan at intel.com
Wed Jan 3 19:59:44 UTC 2018
When DC states are enabled and PSR is active, the hardware enters DC5/DC6
states resulting in the frame counter resetting. The frame counter reset
mess up the vblank counting logic as the diff between the new frame
counter value and the previous is negative, and this negative diff gets
applied as an unsigned value to the vblank count. We cannot reject negative
diffs altogether because they can arise from legitimate frame counter
overflows when there is a long period with vblank disabled. So, this
approach allows for the driver to notice a DC state toggle between a vblank
disable and enable and fill in the missed vblanks.
But, in order to disable DC states when vblank interrupts are required,
the DC_OFF power well has to be disabled in an atomic context. So,
introduce a new VBLANK power domain that can be acquired and released in
atomic contexts with these changes -
1) _vblank_get() and _vblank_put() methods skip the power_domain mutex
and use a spin lock for the DC power well.
2) power_domains->domain_use_count is converted to an atomic_t array so
that it can be updated outside of the power domain mutex.
v3: Squash domain_use_count atomic_t conversion (Maarten)
v2: Fix deadlock by switching irqsave spinlock.
Implement atomic version of get_if_enabled.
Modify power_domain_verify_state to check power well use count and
enabled status atomically.
Rewrite of intel_power_well_{get,put}
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
drivers/gpu/drm/i915/i915_debugfs.c | 2 +-
drivers/gpu/drm/i915/i915_drv.h | 19 +++-
drivers/gpu/drm/i915/intel_display.h | 1 +
drivers/gpu/drm/i915/intel_drv.h | 3 +
drivers/gpu/drm/i915/intel_runtime_pm.c | 195 ++++++++++++++++++++++++++++----
5 files changed, 199 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index d81cb2513069..5a7ce734de02 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2746,7 +2746,7 @@ static int i915_power_domain_info(struct seq_file *m, void *unused)
for_each_power_domain(power_domain, power_well->domains)
seq_printf(m, " %-23s %d\n",
intel_display_power_domain_str(power_domain),
- power_domains->domain_use_count[power_domain]);
+ atomic_read(&power_domains->domain_use_count[power_domain]));
}
mutex_unlock(&power_domains->lock);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index caebd5825279..61a635f03af7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1032,6 +1032,23 @@ struct i915_power_well {
bool has_fuses:1;
} hsw;
};
+
+ /* Lock to serialize access to count, hw_enabled and ops, used for
+ * power wells that have supports_atomix_ctx set to True.
+ */
+ spinlock_t lock;
+
+ /* Indicates that the get/put methods for this power well can be called
+ * in atomic contexts, requires .ops to not sleep. This is valid
+ * only for the DC_OFF power well currently.
+ */
+ bool supports_atomic_ctx;
+
+ /* DC_OFF power well was disabled since the last time vblanks were
+ * disabled.
+ */
+ bool dc_off_disabled;
+
const struct i915_power_well_ops *ops;
};
@@ -1045,7 +1062,7 @@ struct i915_power_domains {
int power_well_count;
struct mutex lock;
- int domain_use_count[POWER_DOMAIN_NUM];
+ atomic_t domain_use_count[POWER_DOMAIN_NUM];
struct i915_power_well *power_wells;
};
diff --git a/drivers/gpu/drm/i915/intel_display.h b/drivers/gpu/drm/i915/intel_display.h
index a0d2b6169361..3e9671ff6f79 100644
--- a/drivers/gpu/drm/i915/intel_display.h
+++ b/drivers/gpu/drm/i915/intel_display.h
@@ -172,6 +172,7 @@ enum intel_display_power_domain {
POWER_DOMAIN_AUX_C,
POWER_DOMAIN_AUX_D,
POWER_DOMAIN_GMBUS,
+ POWER_DOMAIN_VBLANK,
POWER_DOMAIN_MODESET,
POWER_DOMAIN_GT_IRQ,
POWER_DOMAIN_INIT,
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 30f791f89d64..164e62cb047b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1797,6 +1797,9 @@ bool intel_display_power_get_if_enabled(struct drm_i915_private *dev_priv,
enum intel_display_power_domain domain);
void intel_display_power_put(struct drm_i915_private *dev_priv,
enum intel_display_power_domain domain);
+void intel_display_power_vblank_get(struct drm_i915_private *dev_priv,
+ bool *needs_restore);
+void intel_display_power_vblank_put(struct drm_i915_private *dev_priv);
static inline void
assert_rpm_device_not_suspended(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index d758da6156a8..93b324dcc55d 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -56,6 +56,19 @@ static struct i915_power_well *
lookup_power_well(struct drm_i915_private *dev_priv,
enum i915_power_well_id power_well_id);
+/* Optimize for the case when this is called from atomic contexts,
+ * although the case is unlikely.
+ */
+#define power_well_lock(power_well, flags) do { \
+ if (likely(power_well->supports_atomic_ctx)) \
+ spin_lock_irqsave(&power_well->lock, flags); \
+ } while (0)
+
+#define power_well_unlock(power_well, flags) do { \
+ if (likely(power_well->supports_atomic_ctx)) \
+ spin_unlock_irqrestore(&power_well->lock, flags); \
+ } while (0)
+
const char *
intel_display_power_domain_str(enum intel_display_power_domain domain)
{
@@ -126,6 +139,8 @@ intel_display_power_domain_str(enum intel_display_power_domain domain)
return "AUX_D";
case POWER_DOMAIN_GMBUS:
return "GMBUS";
+ case POWER_DOMAIN_VBLANK:
+ return "VBLANK";
case POWER_DOMAIN_INIT:
return "INIT";
case POWER_DOMAIN_MODESET:
@@ -141,6 +156,9 @@ intel_display_power_domain_str(enum intel_display_power_domain domain)
static void intel_power_well_enable(struct drm_i915_private *dev_priv,
struct i915_power_well *power_well)
{
+ if (power_well->supports_atomic_ctx)
+ assert_spin_locked(&power_well->lock);
+
DRM_DEBUG_KMS("enabling %s\n", power_well->name);
power_well->ops->enable(dev_priv, power_well);
power_well->hw_enabled = true;
@@ -149,26 +167,43 @@ static void intel_power_well_enable(struct drm_i915_private *dev_priv,
static void intel_power_well_disable(struct drm_i915_private *dev_priv,
struct i915_power_well *power_well)
{
+ if (power_well->supports_atomic_ctx)
+ assert_spin_locked(&power_well->lock);
+
DRM_DEBUG_KMS("disabling %s\n", power_well->name);
power_well->hw_enabled = false;
power_well->ops->disable(dev_priv, power_well);
}
-static void intel_power_well_get(struct drm_i915_private *dev_priv,
+static void __intel_power_well_get(struct drm_i915_private *dev_priv,
struct i915_power_well *power_well)
{
if (!power_well->count++)
intel_power_well_enable(dev_priv, power_well);
}
+static void intel_power_well_get(struct drm_i915_private *dev_priv,
+ struct i915_power_well *power_well)
+{
+ unsigned long flags = 0;
+
+ power_well_lock(power_well, flags);
+ __intel_power_well_get(dev_priv, power_well);
+ power_well_unlock(power_well, flags);
+}
+
static void intel_power_well_put(struct drm_i915_private *dev_priv,
struct i915_power_well *power_well)
{
+ unsigned long flags = 0;
+
+ power_well_lock(power_well, flags);
WARN(!power_well->count, "Use count on power well %s is already zero",
power_well->name);
if (!--power_well->count)
intel_power_well_disable(dev_priv, power_well);
+ power_well_unlock(power_well, flags);
}
/**
@@ -736,6 +771,7 @@ static void gen9_dc_off_power_well_disable(struct drm_i915_private *dev_priv,
skl_enable_dc6(dev_priv);
else if (dev_priv->csr.allowed_dc_mask & DC_STATE_EN_UPTO_DC5)
gen9_enable_dc5(dev_priv);
+ power_well->dc_off_disabled = true;
}
static void i9xx_power_well_sync_hw_noop(struct drm_i915_private *dev_priv,
@@ -1453,6 +1489,58 @@ static void chv_pipe_power_well_disable(struct drm_i915_private *dev_priv,
chv_set_pipe_power_well(dev_priv, power_well, false);
}
+void intel_display_power_vblank_get(struct drm_i915_private *dev_priv,
+ bool *needs_restore)
+{
+ struct i915_power_domains *power_domains = &dev_priv->power_domains;
+ struct i915_power_well *power_well;
+ enum intel_display_power_domain domain = POWER_DOMAIN_VBLANK;
+
+ *needs_restore = false;
+
+ if (!HAS_CSR(dev_priv))
+ return;
+
+ if (!(HAS_PSR(dev_priv) && dev_priv->psr.sink_support))
+ return;
+
+ intel_runtime_pm_get_noresume(dev_priv);
+
+ for_each_power_domain_well(dev_priv, power_well, BIT_ULL(domain)) {
+ unsigned long flags = 0;
+
+ power_well_lock(power_well, flags);
+ __intel_power_well_get(dev_priv, power_well);
+ *needs_restore = power_well->dc_off_disabled;
+ power_well->dc_off_disabled = false;
+ power_well_unlock(power_well, flags);
+ }
+
+ atomic_inc(&power_domains->domain_use_count[domain]);
+}
+
+void intel_display_power_vblank_put(struct drm_i915_private *dev_priv)
+{
+ struct i915_power_domains *power_domains = &dev_priv->power_domains;
+ struct i915_power_well *power_well;
+ enum intel_display_power_domain domain = POWER_DOMAIN_VBLANK;
+
+ if (!HAS_CSR(dev_priv))
+ return;
+
+ if (!(HAS_PSR(dev_priv) && dev_priv->psr.sink_support))
+ return;
+
+ WARN(atomic_dec_return(&power_domains->domain_use_count[domain]) < 0,
+ "Use count on domain %s was already zero\n",
+ intel_display_power_domain_str(domain));
+
+ for_each_power_domain_well_rev(dev_priv, power_well, BIT_ULL(domain))
+ intel_power_well_put(dev_priv, power_well);
+
+ intel_runtime_pm_put(dev_priv);
+}
+
static void
__intel_display_power_get_domain(struct drm_i915_private *dev_priv,
enum intel_display_power_domain domain)
@@ -1463,7 +1551,7 @@ __intel_display_power_get_domain(struct drm_i915_private *dev_priv,
for_each_power_domain_well(dev_priv, power_well, BIT_ULL(domain))
intel_power_well_get(dev_priv, power_well);
- power_domains->domain_use_count[domain]++;
+ atomic_inc(&power_domains->domain_use_count[domain]);
}
/**
@@ -1492,6 +1580,38 @@ void intel_display_power_get(struct drm_i915_private *dev_priv,
mutex_unlock(&power_domains->lock);
}
+static bool dc_off_get_if_enabled(struct drm_i915_private *dev_priv,
+ enum intel_display_power_domain domain)
+{
+ struct i915_power_well *power_well;
+ bool is_enabled;
+ unsigned long flags = 0;
+
+ power_well = lookup_power_well(dev_priv, SKL_DISP_PW_DC_OFF);
+ if (!power_well || !(power_well->domains & domain))
+ return true;
+
+ power_well_lock(power_well, flags);
+ is_enabled = power_well->hw_enabled;
+ if (is_enabled)
+ __intel_power_well_get(dev_priv, power_well);
+ power_well_unlock(power_well, flags);
+
+ return is_enabled;
+}
+
+static void dc_off_put(struct drm_i915_private *dev_priv,
+ enum intel_display_power_domain domain)
+{
+ struct i915_power_well *power_well;
+
+ power_well = lookup_power_well(dev_priv, SKL_DISP_PW_DC_OFF);
+ if (!power_well || !(power_well->domains & domain))
+ return;
+
+ intel_power_well_put(dev_priv, power_well);
+}
+
/**
* intel_display_power_get_if_enabled - grab a reference for an enabled display power domain
* @dev_priv: i915 device instance
@@ -1508,20 +1628,24 @@ bool intel_display_power_get_if_enabled(struct drm_i915_private *dev_priv,
enum intel_display_power_domain domain)
{
struct i915_power_domains *power_domains = &dev_priv->power_domains;
- bool is_enabled;
+ bool is_enabled = false;
if (!intel_runtime_pm_get_if_in_use(dev_priv))
return false;
mutex_lock(&power_domains->lock);
+ if (!dc_off_get_if_enabled(dev_priv, domain))
+ goto out;
+
if (__intel_display_power_is_enabled(dev_priv, domain)) {
__intel_display_power_get_domain(dev_priv, domain);
is_enabled = true;
- } else {
- is_enabled = false;
}
+ dc_off_put(dev_priv, domain);
+
+out:
mutex_unlock(&power_domains->lock);
if (!is_enabled)
@@ -1549,10 +1673,9 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
mutex_lock(&power_domains->lock);
- WARN(!power_domains->domain_use_count[domain],
- "Use count on domain %s is already zero\n",
+ WARN(atomic_dec_return(&power_domains->domain_use_count[domain]) < 0,
+ "Use count on domain %s was already zero\n",
intel_display_power_domain_str(domain));
- power_domains->domain_use_count[domain]--;
for_each_power_domain_well_rev(dev_priv, power_well, BIT_ULL(domain))
intel_power_well_put(dev_priv, power_well);
@@ -1720,6 +1843,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
BIT_ULL(POWER_DOMAIN_GT_IRQ) | \
BIT_ULL(POWER_DOMAIN_MODESET) | \
BIT_ULL(POWER_DOMAIN_AUX_A) | \
+ BIT_ULL(POWER_DOMAIN_VBLANK) | \
BIT_ULL(POWER_DOMAIN_INIT))
#define BXT_DISPLAY_POWERWELL_2_POWER_DOMAINS ( \
@@ -1743,6 +1867,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
BIT_ULL(POWER_DOMAIN_MODESET) | \
BIT_ULL(POWER_DOMAIN_AUX_A) | \
BIT_ULL(POWER_DOMAIN_GMBUS) | \
+ BIT_ULL(POWER_DOMAIN_VBLANK) | \
BIT_ULL(POWER_DOMAIN_INIT))
#define BXT_DPIO_CMN_A_POWER_DOMAINS ( \
BIT_ULL(POWER_DOMAIN_PORT_DDI_A_LANES) | \
@@ -1803,6 +1928,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
BIT_ULL(POWER_DOMAIN_MODESET) | \
BIT_ULL(POWER_DOMAIN_AUX_A) | \
BIT_ULL(POWER_DOMAIN_GMBUS) | \
+ BIT_ULL(POWER_DOMAIN_VBLANK) | \
BIT_ULL(POWER_DOMAIN_INIT))
#define CNL_DISPLAY_POWERWELL_2_POWER_DOMAINS ( \
@@ -1850,6 +1976,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
CNL_DISPLAY_POWERWELL_2_POWER_DOMAINS | \
BIT_ULL(POWER_DOMAIN_MODESET) | \
BIT_ULL(POWER_DOMAIN_AUX_A) | \
+ BIT_ULL(POWER_DOMAIN_VBLANK) | \
BIT_ULL(POWER_DOMAIN_INIT))
static const struct i915_power_well_ops i9xx_always_on_power_well_ops = {
@@ -2083,9 +2210,12 @@ bool intel_display_power_well_is_enabled(struct drm_i915_private *dev_priv,
{
struct i915_power_well *power_well;
bool ret;
+ unsigned long flags = 0;
power_well = lookup_power_well(dev_priv, power_well_id);
+ power_well_lock(power_well, flags);
ret = power_well->ops->is_enabled(dev_priv, power_well);
+ power_well_unlock(power_well, flags);
return ret;
}
@@ -2120,6 +2250,8 @@ static struct i915_power_well skl_power_wells[] = {
.domains = SKL_DISPLAY_DC_OFF_POWER_DOMAINS,
.ops = &gen9_dc_off_power_well_ops,
.id = SKL_DISP_PW_DC_OFF,
+ .supports_atomic_ctx = true,
+ .dc_off_disabled = false,
},
{
.name = "power well 2",
@@ -2180,6 +2312,8 @@ static struct i915_power_well bxt_power_wells[] = {
.domains = BXT_DISPLAY_DC_OFF_POWER_DOMAINS,
.ops = &gen9_dc_off_power_well_ops,
.id = SKL_DISP_PW_DC_OFF,
+ .supports_atomic_ctx = true,
+ .dc_off_disabled = false,
},
{
.name = "power well 2",
@@ -2235,6 +2369,8 @@ static struct i915_power_well glk_power_wells[] = {
.domains = GLK_DISPLAY_DC_OFF_POWER_DOMAINS,
.ops = &gen9_dc_off_power_well_ops,
.id = SKL_DISP_PW_DC_OFF,
+ .supports_atomic_ctx = true,
+ .dc_off_disabled = false,
},
{
.name = "power well 2",
@@ -2359,6 +2495,8 @@ static struct i915_power_well cnl_power_wells[] = {
.domains = CNL_DISPLAY_DC_OFF_POWER_DOMAINS,
.ops = &gen9_dc_off_power_well_ops,
.id = SKL_DISP_PW_DC_OFF,
+ .supports_atomic_ctx = true,
+ .dc_off_disabled = false,
},
{
.name = "power well 2",
@@ -2487,6 +2625,7 @@ static void assert_power_well_ids_unique(struct drm_i915_private *dev_priv)
int intel_power_domains_init(struct drm_i915_private *dev_priv)
{
struct i915_power_domains *power_domains = &dev_priv->power_domains;
+ struct i915_power_well *power_well;
i915_modparams.disable_power_well =
sanitize_disable_power_well_option(dev_priv,
@@ -2524,6 +2663,10 @@ int intel_power_domains_init(struct drm_i915_private *dev_priv)
set_power_wells(power_domains, i9xx_always_on_power_well);
}
+ for_each_power_well(dev_priv, power_well)
+ if (power_well->supports_atomic_ctx)
+ spin_lock_init(&power_well->lock);
+
assert_power_well_ids_unique(dev_priv);
return 0;
@@ -2571,9 +2714,13 @@ static void intel_power_domains_sync_hw(struct drm_i915_private *dev_priv)
mutex_lock(&power_domains->lock);
for_each_power_well(dev_priv, power_well) {
+ unsigned long flags = 0;
+
+ power_well_lock(power_well, flags);
power_well->ops->sync_hw(dev_priv, power_well);
power_well->hw_enabled = power_well->ops->is_enabled(dev_priv,
power_well);
+ power_well_unlock(power_well, flags);
}
mutex_unlock(&power_domains->lock);
}
@@ -3046,21 +3193,23 @@ void intel_power_domains_suspend(struct drm_i915_private *dev_priv)
bxt_display_core_uninit(dev_priv);
}
-static void intel_power_domains_dump_info(struct drm_i915_private *dev_priv)
+static void intel_power_domains_dump_info(struct drm_i915_private *dev_priv,
+ const int *power_well_use)
{
struct i915_power_domains *power_domains = &dev_priv->power_domains;
struct i915_power_well *power_well;
+ int i = 0;
for_each_power_well(dev_priv, power_well) {
enum intel_display_power_domain domain;
DRM_DEBUG_DRIVER("%-25s %d\n",
- power_well->name, power_well->count);
+ power_well->name, power_well_use[i++]);
for_each_power_domain(domain, power_well->domains)
DRM_DEBUG_DRIVER(" %-23s %d\n",
intel_display_power_domain_str(domain),
- power_domains->domain_use_count[domain]);
+ atomic_read(&power_domains->domain_use_count[domain]));
}
}
@@ -3079,6 +3228,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv)
struct i915_power_domains *power_domains = &dev_priv->power_domains;
struct i915_power_well *power_well;
bool dump_domain_info;
+ int power_well_use[dev_priv->power_domains.power_well_count];
mutex_lock(&power_domains->lock);
@@ -3087,6 +3237,14 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv)
enum intel_display_power_domain domain;
int domains_count;
bool enabled;
+ int well_count, i = 0;
+ unsigned long flags = 0;
+
+ power_well_lock(power_well, flags);
+ well_count = power_well->count;
+ enabled = power_well->ops->is_enabled(dev_priv, power_well);
+ power_well_unlock(power_well, flags);
+ power_well_use[i++] = well_count;
/*
* Power wells not belonging to any domain (like the MISC_IO
@@ -3096,20 +3254,19 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv)
if (!power_well->domains)
continue;
- enabled = power_well->ops->is_enabled(dev_priv, power_well);
- if ((power_well->count || power_well->always_on) != enabled)
+
+ if ((well_count || power_well->always_on) != enabled)
DRM_ERROR("power well %s state mismatch (refcount %d/enabled %d)",
- power_well->name, power_well->count, enabled);
+ power_well->name, well_count, enabled);
domains_count = 0;
for_each_power_domain(domain, power_well->domains)
- domains_count += power_domains->domain_use_count[domain];
+ domains_count += atomic_read(&power_domains->domain_use_count[domain]);
- if (power_well->count != domains_count) {
+ if (well_count != domains_count) {
DRM_ERROR("power well %s refcount/domain refcount mismatch "
"(refcount %d/domains refcount %d)\n",
- power_well->name, power_well->count,
- domains_count);
+ power_well->name, well_count, domains_count);
dump_domain_info = true;
}
}
@@ -3118,7 +3275,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv)
static bool dumped;
if (!dumped) {
- intel_power_domains_dump_info(dev_priv);
+ intel_power_domains_dump_info(dev_priv, power_well_use);
dumped = true;
}
}
--
2.11.0
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