Re: [PATCH 1/2 V4] i915/drm: Add private api for power well usage

["Wang, Xingchao" <xingchao.wang@intel.com>]

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai@suse.de]
> Sent: Tuesday, May 21, 2013 3:18 PM
> To: Wang Xingchao
> Cc: daniel@ffwll.ch; Girdwood, Liam R; david.henningsson@canonical.com; Lin,
> Mengdong; Li, Jocelyn; alsa-devel@alsa-project.org;
> intel-gfx@lists.freedesktop.org; Barnes, Jesse; Zanoni, Paulo R; Wang,
> Xingchao
> Subject: Re: [PATCH 1/2 V4] i915/drm: Add private api for power well usage
> 
> At Mon, 20 May 2013 19:26:57 +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@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_dma.c  |    6 +++
> >  drivers/gpu/drm/i915/i915_drv.h  |   12 +++++
> >  drivers/gpu/drm/i915/intel_drv.h |    4 ++
> >  drivers/gpu/drm/i915/intel_pm.c  |   98
> +++++++++++++++++++++++++++++++++++---
> >  include/drm/i915_powerwell.h     |   36 ++++++++++++++
> >  5 files changed, 149 insertions(+), 7 deletions(-)  create mode
> > 100644 include/drm/i915_powerwell.h
> >
> > diff --git a/drivers/gpu/drm/i915/i915_dma.c
> > b/drivers/gpu/drm/i915/i915_dma.c index a1648eb..2b9010a 100644
> > --- a/drivers/gpu/drm/i915/i915_dma.c
> > +++ b/drivers/gpu/drm/i915/i915_dma.c
> > @@ -1652,6 +1652,9 @@ int i915_driver_load(struct drm_device *dev,
> unsigned long flags)
> >  	/* Start out suspended */
> >  	dev_priv->mm.suspended = 1;
> >
> > +	if (IS_HASWELL(dev))
> > +		i915_init_power_well(dev);
> > +
> >  	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> >  		ret = i915_load_modeset_init(dev);
> >  		if (ret < 0) {
> > @@ -1708,6 +1711,9 @@ int i915_driver_unload(struct drm_device *dev)
> >
> >  	intel_gpu_ips_teardown();
> >
> > +	if (IS_HASWELL(dev))
> > +		i915_remove_power_well(dev);
> > +
> >  	i915_teardown_sysfs(dev);
> >
> >  	if (dev_priv->mm.inactive_shrinker.shrink)
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > b/drivers/gpu/drm/i915/i915_drv.h index 3ac71db..a0f1a6d 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -702,6 +702,15 @@ struct intel_ilk_power_mgmt {
> >  	struct drm_i915_gem_object *renderctx;  };
> >
> > +/* Power well structure for haswell */ struct i915_power_well {
> > +	struct drm_device *device;
> > +	spinlock_t lock;
> > +	/* power well enable/disable usage count */
> > +	int count;
> > +	int i915_request;
> > +};
> > +
> >  struct i915_dri1_state {
> >  	unsigned allow_batchbuffer : 1;
> >  	u32 __iomem *gfx_hws_cpu_addr;
> > @@ -1048,6 +1057,9 @@ typedef struct drm_i915_private {
> >  	 * mchdev_lock in intel_pm.c */
> >  	struct intel_ilk_power_mgmt ips;
> >
> > +	/* Haswell power well */
> > +	struct i915_power_well *hsw_pwr;
> > +
> >  	enum no_fbc_reason no_fbc_reason;
> >
> >  	struct drm_mm_node *compressed_fb;
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index dfcf546..efcccab 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -759,6 +759,10 @@ extern void intel_update_fbc(struct drm_device
> > *dev);  extern void intel_gpu_ips_init(struct drm_i915_private
> > *dev_priv);  extern void intel_gpu_ips_teardown(void);
> >
> > +/* Power well */
> > +extern int i915_init_power_well(struct drm_device *dev); extern void
> > +i915_remove_power_well(struct drm_device *dev);
> > +
> >  extern bool intel_using_power_well(struct drm_device *dev);  extern
> > void intel_init_power_well(struct drm_device *dev);  extern void
> > intel_set_power_well(struct drm_device *dev, bool enable); diff --git
> > a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 0f4b46e..eec7aa8 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 __intel_set_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
> +4372,96 @@
> > void intel_set_power_well(struct drm_device *dev, bool enable)
> >  	}
> >  }
> >
> > +static struct i915_power_well *hsw_pwr;
> > +
> > +/* Display audio driver power well request */ void
> > +i915_request_power_well(void) {
> > +	if (hsw_pwr == NULL)
> > +		return;
> > +
> > +	spin_lock_irq(&hsw_pwr->lock);
> > +	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);
> > +
> > +	/* i915 using power well */
> > +	if (hsw_pwr->i915_request) {
> > +		spin_unlock_irq(&hsw_pwr->lock);
> > +		return;
> > +	}
> > +
> > +	WARN_ON(!hsw_pwr->count);
> > +	if (!--hsw_pwr->count)
> > +		__intel_set_power_well(hsw_pwr->device, false);
> > +	spin_unlock_irq(&hsw_pwr->lock);
> > +}
> > +EXPORT_SYMBOL_GPL(i915_release_power_well);
> 
> This will result in unbalanced refcount.
> When i915_request is true, the count will be never decreased.
> 

Thanks for pointing out this mistake. Will fix it for next version.

--xingchao


> Takashi
> 
> > +
> > +int i915_init_power_well(struct drm_device *dev) {
> > +	struct drm_i915_private *dev_priv = dev->dev_private;
> > +
> > +	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;
> > +
> > +	kfree(dev_priv->hsw_pwr);
> > +	dev_priv->hsw_pwr = NULL;
> > +	hsw_pwr = NULL;
> > +}
> > +
> > +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_ */
> > --
> > 1.7.9.5
> >