At Thu, 23 May 2013 01:04:13 +0800,
Wang Xingchao wrote:
>
> Haswell Display audio depends on power well in graphic side, it should
> request power well before use it and release power well after use.
> I915 will not shutdown power well if it detects audio is using.
> This patch protects display audio crash for Intel Haswell C3 stepping board.
>
> Signed-off-by: Wang Xingchao <xingchao.wang at linux.intel.com>
Just minor points:
> +/* Display audio driver power well request */
> +void i915_request_power_well(void)
> +{
> + if (hsw_pwr == NULL)
> + return;
> +
> + spin_lock_irq(&hsw_pwr->lock);
If both functions are supposed to be called only in non-sleepable
state, there is no merit to use _irq version of spinlock.
OTOH, if this function can be called from non-sleepable context,
spin_lock_irq() is wrong.
That is, the lock here should be either spin_lock() (supposing all
places are not from interrupt context) or spin_lock_irqsave()
(allowing from interrupt context).
> + if (!hsw_pwr->count++ &&
> + !hsw_pwr->i915_request)
> + __intel_set_power_well(hsw_pwr->device, true);
> + spin_unlock_irq(&hsw_pwr->lock);
> +}
> +EXPORT_SYMBOL_GPL(i915_request_power_well);
> +
> +/* Display audio driver power well release */
> +void i915_release_power_well(void)
> +{
> + if (hsw_pwr == NULL)
> + return;
> +
> + spin_lock_irq(&hsw_pwr->lock);
> + WARN_ON(!hsw_pwr->count);
> + if (!--hsw_pwr->count &&
> + !hsw_pwr->i915_request)
> + __intel_set_power_well(hsw_pwr->device, false);
> + spin_unlock_irq(&hsw_pwr->lock);
> +}
> +EXPORT_SYMBOL_GPL(i915_release_power_well);
> +
> +int i915_init_power_well(struct drm_device *dev)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
Since this is a global variable that must be initialized only once,
safer to have
WARN_ON(hsw_pwr);
> + hsw_pwr = kzalloc(sizeof *hsw_pwr, GFP_KERNEL);
> + if (hsw_pwr == NULL)
> + return -ENOMEM;
> +
> + dev_priv->hsw_pwr = hsw_pwr;
> +
> + hsw_pwr->device = dev;
> + spin_lock_init(&hsw_pwr->lock);
> + hsw_pwr->count = 0;
> +
> + return 0;
> +}
> +
> +void i915_remove_power_well(struct drm_device *dev)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
... and
WARN_ON(hsw_ptr != dev_priv->hsw_pwr);
> + kfree(dev_priv->hsw_pwr);
> + dev_priv->hsw_pwr = NULL;
> + hsw_pwr = NULL;
> +}
Takashi
> +
> +void intel_set_power_well(struct drm_device *dev, bool enable)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct i915_power_well *power_well = dev_priv->hsw_pwr;
> +
> + if (!HAS_POWER_WELL(dev))
> + return;
> +
> + if (!i915_disable_power_well && !enable)
> + return;
> +
> + if (!power_well)
> + return;
> +
> + spin_lock_irq(&power_well->lock);
> + power_well->i915_request = enable;
> +
> + /* only reject "disable" power well request */
> + if (power_well->count && !enable) {
> + spin_unlock_irq(&power_well->lock);
> + return;
> + }
> +
> + __intel_set_power_well(dev, enable);
> + spin_unlock_irq(&power_well->lock);
> +}
> +
> /*
> * Starting with Haswell, we have a "Power Down Well" that can be turned off
> * when not needed anymore. We have 4 registers that can request the power well
> diff --git a/include/drm/i915_powerwell.h b/include/drm/i915_powerwell.h
> new file mode 100644
> index 0000000..cfdc884
> --- /dev/null
> +++ b/include/drm/i915_powerwell.h
> @@ -0,0 +1,36 @@
> +/**************************************************************************
> + *
> + * Copyright 2013 Intel Inc.
> + * All Rights Reserved.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the
> + * "Software"), to deal in the Software without restriction, including
> + * without limitation the rights to use, copy, modify, merge, publish,
> + * distribute, sub license, and/or sell copies of the Software, and to
> + * permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the
> + * next paragraph) shall be included in all copies or substantial portions
> + * of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
> + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
> + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
> + * USE OR OTHER DEALINGS IN THE SOFTWARE.
> + *
> + *
> + **************************************************************************/
> +
> +#ifndef _I915_POWERWELL_H_
> +#define _I915_POWERWELL_H_
> +
> +/* For use by hda_i915 driver */
> +extern void i915_request_power_well(void);
> +extern void i915_release_power_well(void);
> +
> +#endif /* _I915_POWERWELL_H_ */
> --
> 1.8.1.2
>
