Re: [alsa-devel] [PATCH] drm/i915: Add private api for power well usage

25 Apr 2013

Hi Daniel/Paulo,
Any comments on this?
Add Jesse and Rafael in loop.
thanks
--xingchao
...
-----Original Message-----
From: Wang, Xingchao
Sent: Wednesday, April 24, 2013 3:29 PM
To: daniel.vetter@ffwll.ch; Zanoni, Paulo R; 'Takashi Iwai'
Cc: ville.syrjala@linux.intel.com; Lin, Mengdong; Girdwood, Liam R; Li, Jocelyn;
intel-gfx@lists.freedesktop.org; alsa-devel@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:

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@linux.intel.com]
Sent: Thursday, April 24, 2014 10:20 PM
To: daniel.vetter@ffwll.ch; Zanoni, Paulo R
Cc: ville.syrjala@linux.intel.com; Lin, Mengdong; Girdwood, Liam R;
Li, Jocelyn; intel-gfx@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@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@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

    