[Intel-gfx] [PATCH 4/4 V6] i915/drm: Add private api for power well usage
Damien Lespiau
damien.lespiau at intel.com
Wed May 29 20:10:30 CEST 2013
On Mon, May 27, 2013 at 05:15:16PM +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>
Daniel, you probably want to give your opinion on the "2 APIs to manage
the power well" discussion below.
In case, the logic seems correct so: with or without the two nitpicks
below (that we can address later if deemed necessary):
Reviewed-by: Damien Lespiau <damien.lespiau at intel.com>
--
Damien
> ---
> 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 | 92 +++++++++++++++++++++++++++++++++++---
> include/drm/i915_powerwell.h | 36 +++++++++++++++
> 5 files changed, 143 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 f5addac..b702915 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 14817de..ea94e5e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -720,6 +720,15 @@ 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;
> @@ -1073,6 +1082,9 @@ 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;
> +
We usually just put the structure inside struct drm_i915_private and
pass it's pointer around instead of an allocation for a few bytes.
We also try quite hard to not be platform specific but feature specific
in our code (eg. HAS_POWER_WELL() and not IS_HASWELL()). hsw_pwr should
probably be renamed to power_well.
> 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 0f35545..8b5017d 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -754,6 +754,10 @@ 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_display_power_enabled(struct drm_device *dev,
> enum intel_display_power_domain domain);
> extern void intel_init_power_well(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 1a76572..f429347 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4502,18 +4502,12 @@ bool intel_display_power_enabled(struct drm_device *dev,
> }
> }
>
> -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;
> @@ -4536,6 +4530,90 @@ 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);
> + 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;
> +
> + 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);
> +}
> +
Based on your previous feedback it seems that we don't yet have a
balanced number of calls to set_power_well() in the i915 driver (we
didn't need to), so blindy replacing the set_power_well() calls get
get()/put() doesn't work.
We probably want that to work at some point, but it needs someone to
have a look at where we want to put the callers on our side.
I think we can live with the transition period where we have these two
APIs, until we go back and fix this on the i915 side. But Daniel may be
of a different opinion.
On a side note, could you describe your test case so we can check we're
not regressing while doing some refactoring?
> /*
> * 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);
Note that, to be fully future proof, this interface is likely to change
to add an enum intel_display_power_domain parameter (and add another
power domain enum for Audio). We don't need to do that now, but a patch
will follow at some point (and probably from me), you've been warned :)
--
Damien
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