[Intel-gfx] [PATCH v2 7/8] drm/i915: Introduce a non-blocking power domain for vblank interrupts
Pandiyan, Dhinakaran
dhinakaran.pandiyan at intel.com
Tue Dec 19 23:20:35 UTC 2017
On Tue, 2017-12-19 at 13:41 -0800, Rodrigo Vivi wrote:
> On Tue, Dec 19, 2017 at 05:26:58AM +0000, Dhinakaran Pandiyan wrote:
> > When DC states are enabled and PSR is active, the hardware enters DC5/DC6
> > states resulting in frame counter resets. The frame counter resets mess
> > up the vblank counting logic. In order to disable DC states when
> > vblank interrupts are required and to disallow DC states when vblanks
> > interrupts are already enabled, introduce a new VBLANK power domain.
> > Since this power domain reference needs to be acquired and released in
> > atomic context, _vblank_get() and _vblank_put() methods skip the
> > power_domain mutex.
> >
> > 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: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>
> + Cc: Imre Deak <imre.deak at intel.com>
>
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > ---
> > drivers/gpu/drm/i915/i915_drv.h | 18 ++++
> > drivers/gpu/drm/i915/intel_drv.h | 3 +
> > drivers/gpu/drm/i915/intel_runtime_pm.c | 184 +++++++++++++++++++++++++++++---
> > 3 files changed, 192 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index ddadeb9eaf49..db597c5ebaed 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -397,6 +397,7 @@ 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,
> > @@ -1476,6 +1477,23 @@ 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;
> > };
> >
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 48676e99316e..6822118f3c4d 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1798,6 +1798,9 @@ 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 992caec1fbc4..fc6812ed6137 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)) \
>
> you mention unlikely on commend and call likely here, why?
It is unlikely that the power well is going to be DC_OFF, but we need to
optimize for that case as it can be called from atomic contexts.
>
> > + 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)
>
> why not (un)likely check here as well?
>
> > + 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);
> > }
> >
> > /**
> > @@ -726,6 +761,7 @@ 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;
>
> why do we need to track this like this?
>
> Seems a big deviation of the hole generic power well state...
If the power well was turned off much later than disable_vblank, the
following enable_vblank call has no idea whether it has to compute the
missed vblanks.
1) put vblank ref -> put AUX A ref -> get vblank ref
dc_off is turned off after we put AUX_A ref, needs computing missed
vblanks.
2) get AUX A ref -> put vblank ref -> get_vblank ref
dc_off is never turned off, no need to compute missed vblanks.
>
> > }
> >
> > static void i9xx_power_well_sync_hw_noop(struct drm_i915_private *dev_priv,
> > @@ -1443,6 +1479,58 @@ 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 (!CAN_PSR(dev_priv))
> > + 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 (!CAN_PSR(dev_priv))
> > + 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)
> > @@ -1482,6 +1570,38 @@ 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
> > @@ -1498,20 +1618,24 @@ 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)
> > @@ -1709,6 +1833,7 @@ 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 ( \
> > @@ -1732,6 +1857,7 @@ 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_DPIO_CMN_A_POWER_DOMAINS ( \
> > BIT_ULL(POWER_DOMAIN_PORT_DDI_A_LANES) | \
> > @@ -1791,6 +1917,7 @@ 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 CNL_DISPLAY_POWERWELL_2_POWER_DOMAINS ( \
> > @@ -1838,6 +1965,7 @@ 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 = {
> > @@ -2071,9 +2199,12 @@ 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;
> > }
> > @@ -2108,6 +2239,8 @@ 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",
> > @@ -2168,6 +2301,8 @@ 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",
> > @@ -2223,6 +2358,8 @@ 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",
> > @@ -2347,6 +2484,8 @@ 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",
> > @@ -2475,6 +2614,7 @@ 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,
> > @@ -2512,6 +2652,10 @@ 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;
> > @@ -2559,9 +2703,13 @@ 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);
> > }
> > @@ -3034,16 +3182,18 @@ 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",
> > @@ -3067,6 +3217,7 @@ 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);
> >
> > @@ -3075,6 +3226,14 @@ 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
> > @@ -3084,20 +3243,19 @@ 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 += 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;
> > }
> > }
> > @@ -3106,7 +3264,7 @@ 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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