Re: [alsa-devel] [PATCH 1/2] drm/915: Add private api for power well usage

[Takashi Iwai <tiwai@suse.de>]

At Tue, 14 May 2013 19:44:18 +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 mobile
> C3 stepping board.
> 
> Signed-off-by: Wang Xingchao <xingchao.wang@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c |   76 +++++++++++++++++++++++++++++++++++----
>  include/drm/i915_powerwell.h    |   36 +++++++++++++++++++
>  2 files changed, 105 insertions(+), 7 deletions(-)
>  create mode 100644 include/drm/i915_powerwell.h
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 0f4b46e..cf7e352 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4344,18 +4344,12 @@ bool intel_using_power_well(struct drm_device *dev)
>  		return true;
>  }
>  
> -void intel_set_power_well(struct drm_device *dev, bool enable)
> +static void enable_power_well(struct drm_device *dev, bool enable)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	bool is_enabled, enable_requested;
>  	uint32_t tmp;
>  
> -	if (!HAS_POWER_WELL(dev))
> -		return;
> -
> -	if (!i915_disable_power_well && !enable)
> -		return;
> -
>  	tmp = I915_READ(HSW_PWR_WELL_DRIVER);
>  	is_enabled = tmp & HSW_PWR_WELL_STATE;
>  	enable_requested = tmp & HSW_PWR_WELL_ENABLE;
> @@ -4378,6 +4372,74 @@ void intel_set_power_well(struct drm_device *dev, bool enable)
>  	}
>  }
>  
> +/* Global drm_device for display audio drvier usage */
> +static struct drm_device *power_well_device;
> +/* Lock protecting power well setting */
> +static DEFINE_SPINLOCK(powerwell_lock);
> +static bool i915_power_well_using;
> +static int hsw_power_count;
> +
> +void i915_request_power_well(void)
> +{
> +	if (!power_well_device)
> +		return;
> +
> +	if (!IS_HASWELL(power_well_device))
> +		return;
> +
> +	spin_lock_irq(&powerwell_lock);
> +	if (!hsw_power_count++) {
> +		enable_power_well(power_well_device, true);
> +	}

Should be
	if (!hsw_power_count++ && !i915_power_well_using)
		enable_power_well(power_well_device, true);


Takashi

> +	spin_unlock_irq(&powerwell_lock);
> +}
> +EXPORT_SYMBOL_GPL(i915_request_power_well);
> +
> +void i915_release_power_well(void)
> +{
> +	if (!power_well_device)
> +		return;
> +
> +	if (!IS_HASWELL(power_well_device))
> +		return;
> +
> +	spin_lock_irq(&powerwell_lock);
> +	WARN_ON(!hsw_power_count);
> +	if (!--hsw_power_count
> +			&& !i915_power_well_using)
> +		enable_power_well(power_well_device, false);
> +	spin_unlock_irq(&powerwell_lock);
> +}
> +EXPORT_SYMBOL_GPL(i915_release_power_well);
> +
> +/* TODO: Call this when i915 module unload */
> +void i915_remove_power_well(void)
> +{
> +	i915_power_well_using = false;
> +	power_well_device = NULL;
> +}
> +
> +void intel_set_power_well(struct drm_device *dev, bool enable)
> +{
> +	if (!HAS_POWER_WELL(dev))
> +		return;
> +
> +	power_well_device = dev;
> +	spin_lock_irq(&powerwell_lock);
> +	i915_power_well_using = enable;
> +	if (!enable && hsw_power_count) {
> +		DRM_DEBUG_KMS("Display audio power well busy using now\n");
> +		goto out;
> +	}
> +
> +	if (!i915_disable_power_well && !enable)
> +		goto out;
> +
> +	enable_power_well(dev, enable);
> +out:
> +	spin_unlock_irq(&powerwell_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_ */
> -- 
> 1.7.9.5
> 
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