[alsa-devel] [PATCH] drm/i915: Add private api for power well usage
Daniel Vetter
daniel.vetter at ffwll.ch
Thu Apr 25 09:52:28 CEST 2013
On Thu, Apr 25, 2013 at 4:36 AM, Wang, Xingchao <xingchao.wang at intel.com> wrote:
> Hi Daniel/Paulo,
>
> Any comments on this?
> Add Jesse and Rafael in loop.
Well I've figured we want to get the power well integration working
before we waste time reviewing an interface which might or might not
quite work. But if you want, I can drop two quick comments:
- I think the functions needs some prefix like i915_
- Imo the power well should just be reference counted (the current
interface name suggests it's generally useable, but actually can only
cope with one request from the audio driver).
- Is the spin_lock (irq-disabling even) really required for the audio
driver to work? power well enabling can take up to 20ms, so this won't
work as-is. Can't we just use a mutex?
- I'd need to see the audio driver side of this to check how this
works for coping with arbitrary module load ordering.
Cheers, Daniel
>
> thanks
> --xingchao
>
>
>> -----Original Message-----
>> From: Wang, Xingchao
>> Sent: Wednesday, April 24, 2013 3:29 PM
>> To: daniel.vetter at ffwll.ch; Zanoni, Paulo R; 'Takashi Iwai'
>> Cc: ville.syrjala at linux.intel.com; Lin, Mengdong; Girdwood, Liam R; Li, Jocelyn;
>> intel-gfx at lists.freedesktop.org; alsa-devel at alsa-project.org; 'Wang Xingchao'
>> Subject: RE: [PATCH] drm/i915: Add private api for power well usage
>>
>> Hi Guys,
>>
>> Sorry I should Add Takashi and alsa maillist in loop.
>>
>> I tested this patch against Daniel's "drm-intel-next-queued" Branch, on
>> Haswell Mobile C3 stepping machines.
>>
>> Test steps:
>> 1. only connect one monitor through HDMI cable 2. echo 1 >
>> /sys/module/i915/parameters/disable_power_well ==> I think this could be set
>> as 1 by default if applied my patch.
>> 3. plug out HDMI cable
>> 4. cat /proc/asound/card0/codec#0
>>
>> At step 3, i915 will try to disable power well but rejected as display audio is
>> using power well.
>> Without the patch, display audio would crash at step 4.
>>
>> I did not list suspend/resume test here, as during suspend sequence, i915 will
>> _ENABLE_ power well, that's a BUG?
>>
>> For me above test case is the only one to reproduce the issue, if you have more
>> ideas and need more test, please let me know.
>>
>> I'm afraid there's some risk because the dependency between alsa driver and
>> drm driver. For example, if i915 module was not loaded, display audio Will call
>> request_power_well() and meet symbol error. Even if i915 module loaded after
>> snd-hda-intel module, there's such risk too. Any comment on this?
>>
>> Another risk is the pointer "power_well_device", it should be set NULL when
>> i915 module unloaded, I added the caller but have no idea where to call it, if
>> anyone has suggestion, that would be fine.
>>
>> thanks
>> --xingchao
>>
>>
>> > -----Original Message-----
>> > From: Wang Xingchao [mailto:xingchao.wang at linux.intel.com]
>> > Sent: Thursday, April 24, 2014 10:20 PM
>> > To: daniel.vetter at ffwll.ch; Zanoni, Paulo R
>> > Cc: ville.syrjala at linux.intel.com; Lin, Mengdong; Girdwood, Liam R;
>> > Li, Jocelyn; intel-gfx at lists.freedesktop.org; Wang, Xingchao; Wang
>> > Xingchao
>> > Subject: [PATCH] drm/i915: Add private api for power well usage
>> >
>> > 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 at linux.intel.com>
>> > ---
>> > drivers/gpu/drm/i915/intel_pm.c | 73
>> > +++++++++++++++++++++++++++++++++++----
>> > include/drm/audio_drm.h | 39 +++++++++++++++++++++
>> > sound/pci/hda/hda_intel.c | 8 +++++
>> > 3 files changed, 113 insertions(+), 7 deletions(-) create mode
>> > 100644 include/drm/audio_drm.h
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_pm.c
>> > b/drivers/gpu/drm/i915/intel_pm.c index 2557926..9983f56 100644
>> > --- a/drivers/gpu/drm/i915/intel_pm.c
>> > +++ b/drivers/gpu/drm/i915/intel_pm.c
>> > @@ -4298,18 +4298,12 @@ bool intel_using_power_well(struct drm_device
>> > *dev)
>> > return true;
>> > }
>> >
>> > -void intel_set_power_well(struct drm_device *dev, bool enable)
>> > +void 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; @@ -4332,6
>> > +4326,71 @@ 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; static bool audio_power_well_using,
>> > +i915_power_well_using;
>> > +/* Lock protecting power well setting */
>> > +DEFINE_SPINLOCK(powerwell_lock);
>> > +
>> > +void request_power_well(void)
>> > +{
>> > + DRM_DEBUG_KMS("Display audio requesting power well\n");
>> > + spin_lock_irq(&powerwell_lock);
>> > + if (!power_well_device)
>> > + goto out;
>> > + if (i915_power_well_using == false)
>> > + set_power_well(power_well_device, true);
>> > + audio_power_well_using = true;
>> > +out:
>> > + spin_unlock_irq(&powerwell_lock);
>> > + return;
>> > +}
>> > +EXPORT_SYMBOL_GPL(request_power_well);
>> > +
>> > +void release_power_well(void)
>> > +{
>> > + DRM_DEBUG_KMS("Display audio releasing power well\n");
>> > + spin_lock_irq(&powerwell_lock);
>> > + if (!power_well_device)
>> > + goto out;
>> > + if (i915_power_well_using == false)
>> > + set_power_well(power_well_device, false);
>> > + audio_power_well_using = false;
>> > +out:
>> > + spin_unlock_irq(&powerwell_lock);
>> > + return;
>> > +}
>> > +EXPORT_SYMBOL_GPL(release_power_well);
>> > +
>> > +/* TODO: Call this when i915 module unload */ void
>> > +remove_power_well(void) {
>> > + spin_lock_irq(&powerwell_lock);
>> > + audio_power_well_using = false;
>> > + i915_power_well_using = false;
>> > + power_well_device = NULL;
>> > + spin_unlock_irq(&powerwell_lock);
>> > +}
>> > +
>> > +void intel_set_power_well(struct drm_device *dev, bool enable) {
>> > + if (!HAS_POWER_WELL(dev))
>> > + return;
>> > +
>> > + spin_lock_irq(&powerwell_lock);
>> > + power_well_device = dev;
>> > + i915_power_well_using = enable;
>> > + if (!enable && audio_power_well_using)
>> > + goto out;
>> > +
>> > + if (!i915_disable_power_well && !enable)
>> > + goto out;
>> > + set_power_well(dev, enable);
>> > +out:
>> > + spin_unlock_irq(&powerwell_lock);
>> > + return;
>> > +}
>> > +
>> > /*
>> > * 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/audio_drm.h
>> > b/include/drm/audio_drm.h new file mode 100644 index 0000000..4412b36
>> > --- /dev/null
>> > +++ b/include/drm/audio_drm.h
>> > @@ -0,0 +1,39 @@
>> >
>> +/**************************************************************
>> > ********
>> > +****
>> > + *
>> > + * 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.
>> > + *
>> > + *
>> > +
>> >
>> +***************************************************************
>> > ********
>> > +***/
>> > +/*
>> > + * Authors:
>> > + * Wang Xingchao <xingchao.wang at intel.com> */
>> > +
>> > +#ifndef _AUDIO_DRM_H_
>> > +#define _AUDIO_DRM_H_
>> > +
>> > +extern void request_power_well(void); extern void
>> > +release_power_well(void);
>> > +
>> > +#endif /* _AUDIO_DRM_H_ */
>> > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
>> > index 418bfc0..59a85de 100644
>> > --- a/sound/pci/hda/hda_intel.c
>> > +++ b/sound/pci/hda/hda_intel.c
>> > @@ -50,6 +50,7 @@
>> > #include <linux/clocksource.h>
>> > #include <linux/time.h>
>> > #include <linux/completion.h>
>> > +#include <drm/audio_drm.h>
>> >
>> > #ifdef CONFIG_X86
>> > /* for snoop control */
>> > @@ -2869,6 +2870,7 @@ static int azx_suspend(struct device *dev)
>> > pci_disable_device(pci);
>> > pci_save_state(pci);
>> > pci_set_power_state(pci, PCI_D3hot);
>> > + release_power_well();
>> > return 0;
>> > }
>> >
>> > @@ -2881,6 +2883,7 @@ static int azx_resume(struct device *dev)
>> > if (chip->disabled)
>> > return 0;
>> >
>> > + request_power_well();
>> > pci_set_power_state(pci, PCI_D0);
>> > pci_restore_state(pci);
>> > if (pci_enable_device(pci) < 0) {
>> > @@ -2913,6 +2916,7 @@ static int azx_runtime_suspend(struct device
>> > *dev)
>> >
>> > azx_stop_chip(chip);
>> > azx_clear_irq_pending(chip);
>> > + release_power_well();
>> > return 0;
>> > }
>> >
>> > @@ -2921,6 +2925,7 @@ static int azx_runtime_resume(struct device *dev)
>> > struct snd_card *card = dev_get_drvdata(dev);
>> > struct azx *chip = card->private_data;
>> >
>> > + request_power_well();
>> > azx_init_pci(chip);
>> > azx_init_chip(chip, 1);
>> > return 0;
>> > @@ -3671,6 +3676,8 @@ static int azx_probe(struct pci_dev *pci,
>> > return -ENOENT;
>> > }
>> >
>> > + request_power_well();
>> > +
>> > err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card);
>> > if (err < 0) {
>> > snd_printk(KERN_ERR "hda-intel: Error creating card!\n"); @@
>> > -3806,6 +3813,7 @@ static void azx_remove(struct pci_dev *pci)
>> > if (card)
>> > snd_card_free(card);
>> > pci_set_drvdata(pci, NULL);
>> > + release_power_well();
>> > }
>> >
>> > /* PCI IDs */
>> > --
>> > 1.7.9.5
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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