Patch "drm/i915: Fix runtime PM for LPE audio" has been added to the 4.11-stable tree

Patch "drm/i915: Fix runtime PM for LPE audio" has been added to the 4.11-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    drm/i915: Fix runtime PM for LPE audio

to the 4.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-i915-fix-runtime-pm-for-lpe-audio.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 668e3b014afb66ab29e134bca7c258527273ac75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 27 Apr 2017 19:02:20 +0300
Subject: drm/i915: Fix runtime PM for LPE audio
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

commit 668e3b014afb66ab29e134bca7c258527273ac75 upstream.

Not calling pm_runtime_enable() means that runtime PM can't be
enabled at all via sysfs. So we definitely need to call it
from somewhere.

Calling it from the driver seems like a bad idea because it
would have to be paired with a pm_runtime_disable() at driver
unload time, otherwise the core gets upset. Also if there's
no LPE audio driver loaded then we couldn't runtime suspend
i915 either.

So it looks like a better plan is to call it from i915 when
we register the platform device. That seems to match how
pci generally does things. I cargo culted the
pm_runtime_forbid() and pm_runtime_set_active() calls from
pci as well.

The exposed runtime PM API is massive an thorougly misleading, so
I don't actually know if this is how you're supposed to use the API
or not. But it seems to work. I can now runtime suspend i915 again
with or without the LPE audio driver loaded, and reloading the
LPE audio driver also seems to work.

Note that powertop won't auto-tune runtime PM for platform devices,
which is a little annoying. So I'm not sure that leaving runtime
PM in "on" mode by default is the best choice here. But I've left
it like that for now at least.

Also remove the comment about there not being much benefit from
LPE audio runtime PM. Not allowing runtime PM blocks i915 runtime
PM, which will also block s0ix, and that could have a measurable
impact on power consumption.

Cc: Takashi Iwai <tiwai@suse.de>
Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Fixes: 0b6b524f3915 ("ALSA: x86: Don't enable runtime PM as default")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170427160231.13337-2-ville.syrjala@linux.intel.com
Reviewed-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit 183c00350ccda86781f6695840e6c5f5b22efbd1)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/i915/intel_lpe_audio.c |    5 +++++
 sound/x86/intel_hdmi_audio.c           |    4 ----
 2 files changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/i915/intel_lpe_audio.c
+++ b/drivers/gpu/drm/i915/intel_lpe_audio.c
@@ -63,6 +63,7 @@
 #include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 
 #include "i915_drv.h"
 #include <linux/delay.h>
@@ -121,6 +122,10 @@ lpe_audio_platdev_create(struct drm_i915
 
 	kfree(rsc);
 
+	pm_runtime_forbid(&platdev->dev);
+	pm_runtime_set_active(&platdev->dev);
+	pm_runtime_enable(&platdev->dev);
+
 	return platdev;
 
 err:
--- a/sound/x86/intel_hdmi_audio.c
+++ b/sound/x86/intel_hdmi_audio.c
@@ -1809,10 +1809,6 @@ static int hdmi_lpe_audio_probe(struct p
 	pdata->notify_pending = false;
 	spin_unlock_irq(&pdata->lpe_audio_slock);
 
-	/* runtime PM isn't enabled as default, since it won't save much on
-	 * BYT/CHT devices; user who want the runtime PM should adjust the
-	 * power/ontrol and power/autosuspend_delay_ms sysfs entries instead
-	 */
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);


Patches currently in stable-queue which might be from ville.syrjala@linux.intel.com are

queue-4.11/drm-i915-fix-runtime-pm-for-lpe-audio.patch