On Mon, Jan 23, 2017 at 10:09:57PM +0100, Hans de Goede wrote: > Listen for PMIC bus access notifications and get FORCEWAKE_ALL while > the bus is accessed to avoid needing to do any forcewakes, which need > PMIC bus access, while the PMIC bus is busy: > > This fixes errors like these showing up in dmesg, usually followed > by a gfx or system freeze: > > [drm:fw_domains_get [i915]] *ERROR* render: timed out waiting for forcewake ack request. > [drm:fw_domains_get [i915]] *MEDIA* render: timed out waiting for forcewake ack request. > i2c_designware 808622C1:06: punit semaphore timed out, resetting > i2c_designware 808622C1:06: PUNIT SEM: 2 > i2c_designware 808622C1:06: couldn't acquire bus ownership > > Downside of this approach is that it causes wakeups whenever the PMIC > bus is accessed. Unfortunately we cannot simply wait for the PMIC bus > to go idle when we hit a race, as forcewakes may be done from interrupt > handlers where we cannot sleep to wait for the i2c PMIC bus access to > finish. > > Note that the notifications and thus the wakeups will only happen on > baytrail / cherrytrail devices using PMICs with a shared i2c bus for > P-Unit and host PMIC access (i2c busses with a _SEM method in their > APCI node), e.g. an axp288 PMIC. > > I plan to write some patches for drivers accessing the PMIC bus to > limit their bus accesses to a bare minimum (e.g. cache registers, do not > update battery level more often then 4 times a minute), to limit the > amount of wakeups. > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241 > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > Tested-by: tagorereddy <tagore.chandan@xxxxxxxxx> > --- > Changes in v2: > -Spelling: P-Unit, PMIC > --- > drivers/gpu/drm/i915/i915_drv.h | 1 + > drivers/gpu/drm/i915/intel_uncore.c | 35 +++++++++++++++++++++++++++++++++++ > 2 files changed, 36 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index c717329..52f7dde 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -721,6 +721,7 @@ struct intel_uncore { > const struct intel_forcewake_range *fw_domains_table; > unsigned int fw_domains_table_entries; > > + struct notifier_block pmic_bus_access_nb; > struct intel_uncore_funcs funcs; > > unsigned fifo_count; > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c > index 3767307..175fe02 100644 > --- a/drivers/gpu/drm/i915/intel_uncore.c > +++ b/drivers/gpu/drm/i915/intel_uncore.c > @@ -25,6 +25,7 @@ > #include "intel_drv.h" > #include "i915_vgpu.h" > > +#include <asm/iosf_mbi.h> > #include <linux/pm_runtime.h> > > #define FORCEWAKE_ACK_TIMEOUT_MS 50 > @@ -429,12 +430,16 @@ static void __intel_uncore_early_sanitize(struct drm_i915_private *dev_priv, > > void intel_uncore_suspend(struct drm_i915_private *dev_priv) > { > + iosf_mbi_unregister_pmic_bus_access_notifier( > + &dev_priv->uncore.pmic_bus_access_nb); > __intel_uncore_forcewake_reset(dev_priv, false); > } > > void intel_uncore_resume(struct drm_i915_private *dev_priv) > { > __intel_uncore_early_sanitize(dev_priv, true); > + iosf_mbi_register_pmic_bus_access_notifier( > + &dev_priv->uncore.pmic_bus_access_nb); > i915_check_and_clear_faults(dev_priv); > } The early/normal/late suspend/resume ordering starts to bother me a little more now. I wonder if we're totally safe wrt. the suspend/resume order of the devices now. > @@ -1390,6 +1395,28 @@ static void intel_uncore_fw_domains_init(struct drm_i915_private *dev_priv) > dev_priv->uncore.fw_domains_table_entries = ARRAY_SIZE((d)); \ > } > > +static int i915_pmic_bus_access_notifier(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct drm_i915_private *dev_priv = container_of(nb, > + struct drm_i915_private, uncore.pmic_bus_access_nb); > + > + switch (action) { > + case MBI_PMIC_BUS_ACCESS_BEGIN: > + /* > + * forcewake all to make sure that we don't need to forcewake > + * any power-planes while the pmic bus is busy. > + */ > + intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL); I must say I don't really like this stuff at all. But if it helps I gues we should go for it. I'd like to see the comment elaborate a bit more on why we think it's is needed. > + break; > + case MBI_PMIC_BUS_ACCESS_END: > + intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL); > + break; > + } > + > + return NOTIFY_OK; > +} > + > void intel_uncore_init(struct drm_i915_private *dev_priv) > { > i915_check_vgpu(dev_priv); > @@ -1399,6 +1426,8 @@ void intel_uncore_init(struct drm_i915_private *dev_priv) > __intel_uncore_early_sanitize(dev_priv, false); > > dev_priv->uncore.unclaimed_mmio_check = 1; > + dev_priv->uncore.pmic_bus_access_nb.notifier_call = > + i915_pmic_bus_access_notifier; > > switch (INTEL_INFO(dev_priv)->gen) { > default: > @@ -1458,6 +1487,9 @@ void intel_uncore_init(struct drm_i915_private *dev_priv) > ASSIGN_READ_MMIO_VFUNCS(vgpu); > } > > + iosf_mbi_register_pmic_bus_access_notifier( > + &dev_priv->uncore.pmic_bus_access_nb); > + > i915_check_and_clear_faults(dev_priv); > } > #undef ASSIGN_WRITE_MMIO_VFUNCS > @@ -1465,6 +1497,9 @@ void intel_uncore_init(struct drm_i915_private *dev_priv) > > void intel_uncore_fini(struct drm_i915_private *dev_priv) > { > + iosf_mbi_unregister_pmic_bus_access_notifier( > + &dev_priv->uncore.pmic_bus_access_nb); > + > /* Paranoia: make sure we have disabled everything before we exit. */ > intel_uncore_sanitize(dev_priv); > __intel_uncore_forcewake_reset(dev_priv, false); > -- > 2.9.3 -- Ville Syrjälä Intel OTC -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
