| Message ID | 20171219052659.2355-7-dhinakaran.pandiyan@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hey, Op 19-12-17 om 06:26 schreef Dhinakaran Pandiyan: > Convert the power_domains->domain_use_count array that tracks per-domain > use count to atomic_t type. This is needed to be able to read/write the use > counts outside of the power domain mutex. > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> > --- > drivers/gpu/drm/i915/i915_debugfs.c | 2 +- > drivers/gpu/drm/i915/i915_drv.h | 2 +- > drivers/gpu/drm/i915/intel_runtime_pm.c | 11 +++++------ > 3 files changed, 7 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > index 1a7b28f62570..1f1d9162f2c2 100644 > --- a/drivers/gpu/drm/i915/i915_debugfs.c > +++ b/drivers/gpu/drm/i915/i915_debugfs.c > @@ -2764,7 +2764,7 @@ 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 1e4e613e7b41..ddadeb9eaf49 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -1489,7 +1489,7 @@ 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_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c > index 96ab74f3d101..992caec1fbc4 100644 > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c > @@ -1453,7 +1453,7 @@ __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]); > } > > /** > @@ -1539,10 +1539,9 @@ 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); > @@ -3049,7 +3048,7 @@ static void intel_power_domains_dump_info(struct drm_i915_private *dev_priv) > 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])); > } > } > > @@ -3092,7 +3091,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv) > > 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) { > DRM_ERROR("power well %s refcount/domain refcount mismatch " I can imagine this will start failing really badly. The previous code assumed that everything is protected by power_domains->lock, and now this changes makes it no longer the case.. I see the rest of the code changes things even more, but it would be better if the locking rework was done in a single patch, and not bolted on.. And instead of using atomic_t, there is a refcount implementation in refcount.h, it could be used here for locking power wells only if it would drop to zero.. Cheers, Maarten
On Thu, 2017-12-21 at 13:37 +0100, Maarten Lankhorst wrote: > Hey, > > Op 19-12-17 om 06:26 schreef Dhinakaran Pandiyan: > > Convert the power_domains->domain_use_count array that tracks per-domain > > use count to atomic_t type. This is needed to be able to read/write the use > > counts outside of the power domain mutex. > > > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> > > --- > > drivers/gpu/drm/i915/i915_debugfs.c | 2 +- > > drivers/gpu/drm/i915/i915_drv.h | 2 +- > > drivers/gpu/drm/i915/intel_runtime_pm.c | 11 +++++------ > > 3 files changed, 7 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > > index 1a7b28f62570..1f1d9162f2c2 100644 > > --- a/drivers/gpu/drm/i915/i915_debugfs.c > > +++ b/drivers/gpu/drm/i915/i915_debugfs.c > > @@ -2764,7 +2764,7 @@ 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 1e4e613e7b41..ddadeb9eaf49 100644 > > --- a/drivers/gpu/drm/i915/i915_drv.h > > +++ b/drivers/gpu/drm/i915/i915_drv.h > > @@ -1489,7 +1489,7 @@ 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_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c > > index 96ab74f3d101..992caec1fbc4 100644 > > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c > > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c > > @@ -1453,7 +1453,7 @@ __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]); > > } > > > > /** > > @@ -1539,10 +1539,9 @@ 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); > > @@ -3049,7 +3048,7 @@ static void intel_power_domains_dump_info(struct drm_i915_private *dev_priv) > > 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])); > > } > > } > > > > @@ -3092,7 +3091,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv) > > > > 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) { > > DRM_ERROR("power well %s refcount/domain refcount mismatch " > > I can imagine this will start failing really badly. The previous code assumed that > everything is protected by power_domains->lock, and now this changes makes it no > longer the case.. > This won't fail until the next patch where it is read outside of the mutex. And that patch reads these values within the new spin_lock. I was trying to split the changes so that the next patch does not become too heavy. > I see the rest of the code changes things even more, but it would be better if the > locking rework was done in a single patch, and not bolted on.. > I see your point, I can squash them together. > And instead of using atomic_t, there is a refcount implementation in refcount.h, > it could be used here for locking power wells only if it would drop to zero.. > So, the power_wells have another refcount (controls the power well enable and disable), which needs the lock. Not very clear why we need to lock the power wells if the domain_use_count goes to zero. The domain_use_count array that I am converting over to atomic_t is used for debug and verifying that the power well users are accounted for. It does not control any hardware state. And the reason I am converting it to atomic_t is to update it outside the spin locks. Let me know if my understand is wrong. > Cheers, > Maarten > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 1a7b28f62570..1f1d9162f2c2 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -2764,7 +2764,7 @@ 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 1e4e613e7b41..ddadeb9eaf49 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1489,7 +1489,7 @@ 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_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c index 96ab74f3d101..992caec1fbc4 100644 --- a/drivers/gpu/drm/i915/intel_runtime_pm.c +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c @@ -1453,7 +1453,7 @@ __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]); } /** @@ -1539,10 +1539,9 @@ 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); @@ -3049,7 +3048,7 @@ static void intel_power_domains_dump_info(struct drm_i915_private *dev_priv) 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])); } } @@ -3092,7 +3091,7 @@ void intel_power_domains_verify_state(struct drm_i915_private *dev_priv) 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) { DRM_ERROR("power well %s refcount/domain refcount mismatch "
Convert the power_domains->domain_use_count array that tracks per-domain use count to atomic_t type. This is needed to be able to read/write the use counts outside of the power domain mutex. Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> --- drivers/gpu/drm/i915/i915_debugfs.c | 2 +- drivers/gpu/drm/i915/i915_drv.h | 2 +- drivers/gpu/drm/i915/intel_runtime_pm.c | 11 +++++------ 3 files changed, 7 insertions(+), 8 deletions(-)