Re: [PATCH 1/8] drm/i915: Rebalance runtime pm vs forcewake

Deepak S
2014-12-11T10:03:18Z

On Monday 08 December 2014 11:57 PM, Mika Kuoppala wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
>
> Calling intel_runtime_pm_put() is illegal from a soft-irq context, so
> revert the crude hack
>
> commit aa0b3b5bb8768c1a6a6788869d9c7015eae7e80c
> Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Date: Tue Apr 1 14:55:07 2014 -0300
>
> drm/i915: don't schedule force_wake_timer at gen6_read
>
> and apply the single line corrective instead.
>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=80913
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 1 +
> drivers/gpu/drm/i915/intel_uncore.c | 18 ++++++------------
> 2 files changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 71be3c9..706b122 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1402,6 +1402,7 @@ static int intel_runtime_suspend(struct device *device)
> }
>
> del_timer_sync(&dev_priv->gpu_error.hangcheck_timer);
> + intel_uncore_forcewake_reset(dev, false);
> dev_priv->pm.suspended = true;
>
> /*
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 46de8d7..38ac389 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -449,8 +449,6 @@ static void gen6_force_wake_timer(unsigned long arg)
> if (--dev_priv->uncore.forcewake_count == 0)
> dev_priv->uncore.funcs.force_wake_put(dev_priv, FORCEWAKE_ALL);
> spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> -
> - intel_runtime_pm_put(dev_priv);
> }
>
> void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
> @@ -586,7 +584,6 @@ void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv, int fw_engine)
> void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv, int fw_engine)
> {
> unsigned long irqflags;
> - bool delayed = false;
>
> if (!dev_priv->uncore.funcs.force_wake_put)
> return;
> @@ -603,21 +600,19 @@ void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv, int fw_engine)
> goto out;
> }
>
> -
> spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> WARN_ON(!dev_priv->uncore.forcewake_count);
>
> if (--dev_priv->uncore.forcewake_count == 0) {
> dev_priv->uncore.forcewake_count++;
> - delayed = true;
> mod_timer_pinned(&dev_priv->uncore.force_wake_timer,
> jiffies + 1);
> }
> +
> spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>
> out:
> - if (!delayed)
> - intel_runtime_pm_put(dev_priv);
> + intel_runtime_pm_put(dev_priv);
> }
>
> void assert_force_wake_inactive(struct drm_i915_private *dev_priv)
> @@ -777,12 +772,11 @@ gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
> NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
> dev_priv->uncore.funcs.force_wake_get(dev_priv, \
> FORCEWAKE_ALL); \
> - val = __raw_i915_read##x(dev_priv, reg); \
> - dev_priv->uncore.funcs.force_wake_put(dev_priv, \
> - FORCEWAKE_ALL); \
> - } else { \
> - val = __raw_i915_read##x(dev_priv, reg); \
> + dev_priv->uncore.forcewake_count++; \
> + mod_timer_pinned(&dev_priv->uncore. , \
> + jiffies + 1); \

why timer, we can do a put after register read right?

Other changes looks fine to me
Reviewed-by: Deepak S <deepak.s@linux.intel.com>

> } \
> + val = __raw_i915_read##x(dev_priv, reg); \
> hsw_unclaimed_reg_debug(dev_priv, reg, true, false); \
> REG_READ_FOOTER; \
> }