Hans de Goede <hdegoede@xxxxxxxxxx> writes: > Hi, > > On 10-01-18 13:55, Chris Wilson wrote: >> While we talk to the punit over its sideband, we need to prevent the cpu >> from sleeping in order to prevent a potential machine hang. >> >> Note that by itself, it appears that pm_qos_update_request (via >> intel_idle) doesn't provide a sufficient barrier to ensure that all core >> are indeed awake (out of Cstate) and that the package is awake. To do so, >> we need to supplement the pm_qos with a manual ping on_each_cpu. >> >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109051 >> References: https://bugs.freedesktop.org/show_bug.cgi?id=102657 >> References: https://bugzilla.kernel.org/show_bug.cgi?id=195255 >> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> >> Cc: Hans de Goede <hdegoede@xxxxxxxxxx> > > Interesting, I've added similar pm_qos code in > drivers/i2c/busses/i2c-designware-baytrail.c quite a while ago because > the CPU transitioning to higher C-state while accessing the i2c bus to > the pmic (if it is shared) also causes the SoC to hang. > > I could reproduce this quite easily by doing "i2cdump" on the pmic, > usually the system would hang in one or 2 i2cdump calls. > > Note IIRC this was on CHT. > > I see that you also block any pmic-i2c bus accesses while doing > punit access by calling iosf_mbi_punit_acquire(); > > Maybe we need to move the pm_qos stuff out of > drivers/i2c/busses/i2c-designware-baytrail.c > > And into iosf_mbi_punit_acquire? The i2c-designware-baytrail.c > does its own pm_qos dance directly after calling > iosf_mbi_punit_acquire / before calling iosf_mbi_punit_release(); > > Note the i2c-designware-baytrail.c version lacks the ping, but it > should, probably have it too. The ping, if it deemed worthy, should find its way into intel_idle parts. -Mika > > Regards, > > Hans > > > >> --- >> drivers/gpu/drm/i915/i915_drv.c | 6 ++++ >> drivers/gpu/drm/i915/i915_drv.h | 1 + >> drivers/gpu/drm/i915/intel_sideband.c | 61 ++++++++++++++++++++++++----------- >> 3 files changed, 50 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c >> index 6c8da9d20c33..d4b90cc0130b 100644 >> --- a/drivers/gpu/drm/i915/i915_drv.c >> +++ b/drivers/gpu/drm/i915/i915_drv.c >> @@ -902,6 +902,9 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv, >> spin_lock_init(&dev_priv->uncore.lock); >> >> mutex_init(&dev_priv->sb_lock); >> + pm_qos_add_request(&dev_priv->sb_qos, >> + PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE); >> + >> mutex_init(&dev_priv->modeset_restore_lock); >> mutex_init(&dev_priv->av_mutex); >> mutex_init(&dev_priv->wm.wm_mutex); >> @@ -953,6 +956,9 @@ static void i915_driver_cleanup_early(struct drm_i915_private *dev_priv) >> intel_irq_fini(dev_priv); >> i915_workqueues_cleanup(dev_priv); >> i915_engines_cleanup(dev_priv); >> + >> + pm_qos_remove_request(&dev_priv->sb_qos); >> + mutex_destroy(&dev_priv->sb_lock); >> } >> >> static int i915_mmio_setup(struct drm_i915_private *dev_priv) >> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h >> index a689396d0ff6..ff3f9effc0bb 100644 >> --- a/drivers/gpu/drm/i915/i915_drv.h >> +++ b/drivers/gpu/drm/i915/i915_drv.h >> @@ -1887,6 +1887,7 @@ struct drm_i915_private { >> >> /* Sideband mailbox protection */ >> struct mutex sb_lock; >> + struct pm_qos_request sb_qos; >> >> /** Cached value of IMR to avoid reads in updating the bitfield */ >> union { >> diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c >> index 75c872bb8cc9..02bdd2e2cef6 100644 >> --- a/drivers/gpu/drm/i915/intel_sideband.c >> +++ b/drivers/gpu/drm/i915/intel_sideband.c >> @@ -22,6 +22,8 @@ >> * >> */ >> >> +#include <asm/iosf_mbi.h> >> + >> #include "i915_drv.h" >> #include "intel_drv.h" >> >> @@ -39,18 +41,20 @@ >> /* Private register write, double-word addressing, non-posted */ >> #define SB_CRWRDA_NP 0x07 >> >> -static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn, >> - u32 port, u32 opcode, u32 addr, u32 *val) >> +static void ping(void *info) >> { >> - u32 cmd, be = 0xf, bar = 0; >> - bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP); >> +} >> >> - cmd = (devfn << IOSF_DEVFN_SHIFT) | (opcode << IOSF_OPCODE_SHIFT) | >> - (port << IOSF_PORT_SHIFT) | (be << IOSF_BYTE_ENABLES_SHIFT) | >> - (bar << IOSF_BAR_SHIFT); >> +static int vlv_sideband_rw(struct drm_i915_private *dev_priv, >> + u32 devfn, u32 port, u32 opcode, >> + u32 addr, u32 *val) >> +{ >> + const bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP); >> + int err; >> >> - WARN_ON(!mutex_is_locked(&dev_priv->sb_lock)); >> + lockdep_assert_held(&dev_priv->sb_lock); >> >> + /* Flush the previous comms, just in case it failed last time. */ >> if (intel_wait_for_register(dev_priv, >> VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0, >> 5)) { >> @@ -59,22 +63,43 @@ static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn, >> return -EAGAIN; >> } >> >> - I915_WRITE(VLV_IOSF_ADDR, addr); >> - I915_WRITE(VLV_IOSF_DATA, is_read ? 0 : *val); >> - I915_WRITE(VLV_IOSF_DOORBELL_REQ, cmd); >> + iosf_mbi_punit_acquire(); >> >> - if (intel_wait_for_register(dev_priv, >> - VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0, >> - 5)) { >> + /* >> + * Prevent the cpu from sleeping while we use this sideband, otherwise >> + * the punit may cause a machine hang. >> + */ >> + pm_qos_update_request(&dev_priv->sb_qos, 0); >> + on_each_cpu(ping, NULL, 1); >> + preempt_disable(); >> + >> + I915_WRITE_FW(VLV_IOSF_ADDR, addr); >> + I915_WRITE_FW(VLV_IOSF_DATA, is_read ? 0 : *val); >> + I915_WRITE_FW(VLV_IOSF_DOORBELL_REQ, >> + (devfn << IOSF_DEVFN_SHIFT) | >> + (opcode << IOSF_OPCODE_SHIFT) | >> + (port << IOSF_PORT_SHIFT) | >> + (0xf << IOSF_BYTE_ENABLES_SHIFT) | >> + (0 << IOSF_BAR_SHIFT) | >> + IOSF_SB_BUSY); >> + >> + if (__intel_wait_for_register_fw(dev_priv, >> + VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0, >> + 10000, 0, NULL) == 0) { >> + if (is_read) >> + *val = I915_READ_FW(VLV_IOSF_DATA); >> + err = 0; >> + } else { >> DRM_DEBUG_DRIVER("IOSF sideband finish wait (%s) timed out\n", >> is_read ? "read" : "write"); >> - return -ETIMEDOUT; >> + err = -ETIMEDOUT; >> } >> >> - if (is_read) >> - *val = I915_READ(VLV_IOSF_DATA); >> + preempt_enable(); >> + pm_qos_update_request(&dev_priv->sb_qos, PM_QOS_DEFAULT_VALUE); >> + iosf_mbi_punit_release(); >> >> - return 0; >> + return err; >> } >> >> u32 vlv_punit_read(struct drm_i915_private *dev_priv, u32 addr) >> _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
