[Intel-gfx] [PATCH 15/36] drm/i915: Mark up Ironlake ips with rpm wakerefs
Sagar Arun Kamble
sagar.a.kamble at intel.com
Fri Mar 16 04:58:22 UTC 2018
On 3/14/2018 3:07 PM, Chris Wilson wrote:
> Currently Ironlake operates under the assumption that rpm awake (and its
> error checking is disabled). As such, we have missed a few places where we
> access registers without taking the rpm wakeref and thus trigger
> warnings. intel_ips being one culprit.
>
> As this involved adding a potentially sleeping rpm_get, we have to
> rearrange the spinlocks slightly and so switch to acquiring a device-ref
> under the spinlock rather than hold the spinlock for the whole
> operation. To be consistent, we make the change in pattern common to the
> intel_ips interface even though this adds a few more atomic operations
> than necessary in a few cases.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 3 +
> drivers/gpu/drm/i915/intel_pm.c | 138 ++++++++++++++++++++--------------------
> 2 files changed, 73 insertions(+), 68 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 3d0b7353fb09..5c28990aab7f 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1440,6 +1440,9 @@ void i915_driver_unload(struct drm_device *dev)
>
> i915_driver_unregister(dev_priv);
>
> + /* Flush any external code that still may be under the RCU lock */
> + synchronize_rcu();
> +
Hi Chris,
Will this rcu change be equivalent to
rcu_assign_pointer(i915_mch_dev, dev_priv) in gpu_ips_init
rcu_assign_pointer(i915_mch_dev, NULL) in gpu_ips_teardown
eliminating smp_store_mb from init/teardown and synchronize_rcu here.
Thanks,
Sagar
> if (i915_gem_suspend(dev_priv))
> DRM_ERROR("failed to idle hardware; continuing to unload!\n");
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 447811c5be35..a2ebf66ff9ed 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5930,10 +5930,6 @@ void intel_init_ipc(struct drm_i915_private *dev_priv)
> */
> DEFINE_SPINLOCK(mchdev_lock);
>
> -/* Global for IPS driver to get at the current i915 device. Protected by
> - * mchdev_lock. */
> -static struct drm_i915_private *i915_mch_dev;
> -
> bool ironlake_set_drps(struct drm_i915_private *dev_priv, u8 val)
> {
> u16 rgvswctl;
> @@ -7577,11 +7573,13 @@ unsigned long i915_chipset_val(struct drm_i915_private *dev_priv)
> if (!IS_GEN5(dev_priv))
> return 0;
>
> + intel_runtime_pm_get(dev_priv);
> spin_lock_irq(&mchdev_lock);
>
> val = __i915_chipset_val(dev_priv);
>
> spin_unlock_irq(&mchdev_lock);
> + intel_runtime_pm_put(dev_priv);
>
> return val;
> }
> @@ -7661,11 +7659,13 @@ void i915_update_gfx_val(struct drm_i915_private *dev_priv)
> if (!IS_GEN5(dev_priv))
> return;
>
> + intel_runtime_pm_get(dev_priv);
> spin_lock_irq(&mchdev_lock);
>
> __i915_update_gfx_val(dev_priv);
>
> spin_unlock_irq(&mchdev_lock);
> + intel_runtime_pm_put(dev_priv);
> }
>
> static unsigned long __i915_gfx_val(struct drm_i915_private *dev_priv)
> @@ -7712,15 +7712,32 @@ unsigned long i915_gfx_val(struct drm_i915_private *dev_priv)
> if (!IS_GEN5(dev_priv))
> return 0;
>
> + intel_runtime_pm_get(dev_priv);
> spin_lock_irq(&mchdev_lock);
>
> val = __i915_gfx_val(dev_priv);
>
> spin_unlock_irq(&mchdev_lock);
> + intel_runtime_pm_put(dev_priv);
>
> return val;
> }
>
> +static struct drm_i915_private *i915_mch_dev;
> +
> +static struct drm_i915_private *mchdev_get(void)
> +{
> + struct drm_i915_private *i915;
> +
> + rcu_read_lock();
> + i915 = i915_mch_dev;
> + if (!kref_get_unless_zero(&i915->drm.ref))
> + i915 = NULL;
> + rcu_read_unlock();
> +
> + return i915;
> +}
> +
> /**
> * i915_read_mch_val - return value for IPS use
> *
> @@ -7729,23 +7746,22 @@ unsigned long i915_gfx_val(struct drm_i915_private *dev_priv)
> */
> unsigned long i915_read_mch_val(void)
> {
> - struct drm_i915_private *dev_priv;
> - unsigned long chipset_val, graphics_val, ret = 0;
> -
> - spin_lock_irq(&mchdev_lock);
> - if (!i915_mch_dev)
> - goto out_unlock;
> - dev_priv = i915_mch_dev;
> -
> - chipset_val = __i915_chipset_val(dev_priv);
> - graphics_val = __i915_gfx_val(dev_priv);
> + struct drm_i915_private *i915;
> + unsigned long chipset_val, graphics_val;
>
> - ret = chipset_val + graphics_val;
> + i915 = mchdev_get();
> + if (!i915)
> + return 0;
>
> -out_unlock:
> + intel_runtime_pm_get(i915);
> + spin_lock_irq(&mchdev_lock);
> + chipset_val = __i915_chipset_val(i915);
> + graphics_val = __i915_gfx_val(i915);
> spin_unlock_irq(&mchdev_lock);
> + intel_runtime_pm_put(i915);
>
> - return ret;
> + drm_dev_put(&i915->drm);
> + return chipset_val + graphics_val;
> }
> EXPORT_SYMBOL_GPL(i915_read_mch_val);
>
> @@ -7756,23 +7772,19 @@ EXPORT_SYMBOL_GPL(i915_read_mch_val);
> */
> bool i915_gpu_raise(void)
> {
> - struct drm_i915_private *dev_priv;
> - bool ret = true;
> -
> - spin_lock_irq(&mchdev_lock);
> - if (!i915_mch_dev) {
> - ret = false;
> - goto out_unlock;
> - }
> - dev_priv = i915_mch_dev;
> + struct drm_i915_private *i915;
>
> - if (dev_priv->ips.max_delay > dev_priv->ips.fmax)
> - dev_priv->ips.max_delay--;
> + i915 = mchdev_get();
> + if (!i915)
> + return false;
>
> -out_unlock:
> + spin_lock_irq(&mchdev_lock);
> + if (i915->ips.max_delay > i915->ips.fmax)
> + i915->ips.max_delay--;
> spin_unlock_irq(&mchdev_lock);
>
> - return ret;
> + drm_dev_put(&i915->drm);
> + return true;
> }
> EXPORT_SYMBOL_GPL(i915_gpu_raise);
>
> @@ -7784,23 +7796,19 @@ EXPORT_SYMBOL_GPL(i915_gpu_raise);
> */
> bool i915_gpu_lower(void)
> {
> - struct drm_i915_private *dev_priv;
> - bool ret = true;
> + struct drm_i915_private *i915;
>
> - spin_lock_irq(&mchdev_lock);
> - if (!i915_mch_dev) {
> - ret = false;
> - goto out_unlock;
> - }
> - dev_priv = i915_mch_dev;
> -
> - if (dev_priv->ips.max_delay < dev_priv->ips.min_delay)
> - dev_priv->ips.max_delay++;
> + i915 = mchdev_get();
> + if (!i915)
> + return false;
>
> -out_unlock:
> + spin_lock_irq(&mchdev_lock);
> + if (i915->ips.max_delay < i915->ips.min_delay)
> + i915->ips.max_delay++;
> spin_unlock_irq(&mchdev_lock);
>
> - return ret;
> + drm_dev_put(&i915->drm);
> + return true;
> }
> EXPORT_SYMBOL_GPL(i915_gpu_lower);
>
> @@ -7811,13 +7819,16 @@ EXPORT_SYMBOL_GPL(i915_gpu_lower);
> */
> bool i915_gpu_busy(void)
> {
> - bool ret = false;
> + struct drm_i915_private *i915;
> + bool ret;
>
> - spin_lock_irq(&mchdev_lock);
> - if (i915_mch_dev)
> - ret = i915_mch_dev->gt.awake;
> - spin_unlock_irq(&mchdev_lock);
> + i915 = mchdev_get();
> + if (!i915)
> + return false;
> +
> + ret = i915->gt.awake;
>
> + drm_dev_put(&i915->drm);
> return ret;
> }
> EXPORT_SYMBOL_GPL(i915_gpu_busy);
> @@ -7830,24 +7841,19 @@ EXPORT_SYMBOL_GPL(i915_gpu_busy);
> */
> bool i915_gpu_turbo_disable(void)
> {
> - struct drm_i915_private *dev_priv;
> - bool ret = true;
> -
> - spin_lock_irq(&mchdev_lock);
> - if (!i915_mch_dev) {
> - ret = false;
> - goto out_unlock;
> - }
> - dev_priv = i915_mch_dev;
> -
> - dev_priv->ips.max_delay = dev_priv->ips.fstart;
> + struct drm_i915_private *i915;
> + bool ret;
>
> - if (!ironlake_set_drps(dev_priv, dev_priv->ips.fstart))
> - ret = false;
> + i915 = mchdev_get();
> + if (!i915)
> + return false;
>
> -out_unlock:
> + spin_lock_irq(&mchdev_lock);
> + i915->ips.max_delay = i915->ips.fstart;
> + ret = ironlake_set_drps(i915, i915->ips.fstart);
> spin_unlock_irq(&mchdev_lock);
>
> + drm_dev_put(&i915->drm);
> return ret;
> }
> EXPORT_SYMBOL_GPL(i915_gpu_turbo_disable);
> @@ -7876,18 +7882,14 @@ void intel_gpu_ips_init(struct drm_i915_private *dev_priv)
> {
> /* We only register the i915 ips part with intel-ips once everything is
> * set up, to avoid intel-ips sneaking in and reading bogus values. */
> - spin_lock_irq(&mchdev_lock);
> - i915_mch_dev = dev_priv;
> - spin_unlock_irq(&mchdev_lock);
> + smp_store_mb(i915_mch_dev, dev_priv);
>
> ips_ping_for_i915_load();
> }
>
> void intel_gpu_ips_teardown(void)
> {
> - spin_lock_irq(&mchdev_lock);
> - i915_mch_dev = NULL;
> - spin_unlock_irq(&mchdev_lock);
> + smp_store_mb(i915_mch_dev, NULL);
> }
>
> static void intel_init_emon(struct drm_i915_private *dev_priv)
--
Thanks,
Sagar
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