From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sriram Periyasamy Subject: Re: [PATCH] ASoC: Intel: Power down links before turning off display audio power Date: Tue, 26 Jun 2018 16:54:01 +0530 Message-ID: <20180626112401.GA3093@intel.com> References: <1529659551-22902-1-git-send-email-sriramx.periyasamy@intel.com> <20180625085348.GA30506@intel.com> <20180625092316.GA13073@intel.com> <20180625145112.GA14734@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by alsa0.perex.cz (Postfix) with ESMTP id 93CE52675C8 for ; Tue, 26 Jun 2018 13:27:44 +0200 (CEST) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: ALSA ML , Patches Audio , Pierre-Louis Bossart , Liam Girdwood , Mark Brown , Sanyog Kale List-Id: alsa-devel@alsa-project.org On Mon, Jun 25, 2018 at 05:18:27PM +0200, Takashi Iwai wrote: > On Mon, 25 Jun 2018 16:51:12 +0200, > Sriram Periyasamy wrote: > > > > On Mon, Jun 25, 2018 at 11:53:59AM +0200, Takashi Iwai wrote: > > > On Mon, 25 Jun 2018 11:23:17 +0200, > > > Sriram Periyasamy wrote: > > > > > > > > On Mon, Jun 25, 2018 at 11:08:13AM +0200, Takashi Iwai wrote: > > > > > On Mon, 25 Jun 2018 10:53:49 +0200, > > > > > Sriram Periyasamy wrote: > > > > > > > > > > > > On Fri, Jun 22, 2018 at 07:14:50PM +0200, Takashi Iwai wrote: > > > > > > > On Fri, 22 Jun 2018 18:42:24 +0200, > > > > > > > Pierre-Louis Bossart wrote: > > > > > > > > > > > > > > > > On 6/22/18 4:25 AM, Sriram Periyasamy wrote: > > > > > > > > > On certain platforms, Display HDMI HDA codec was not going to sleep state > > > > > > > > > after the use when links are powered down after turning off the display > > > > > > > > > power. As per the HW recommendation, links are powered down before turning > > > > > > > > > off the display power to ensure that the codec goes to sleep state. > > > > > > > > > > > > > > > > The change looks ok, I am still not clear on display power > > > > > > > > management. snd_hdac_display_power is called both from hdac_hdmi.c and > > > > > > > > skl.c in the respective probe/suspend/resume routines, wondering if > > > > > > > > this is redundant or intentional. > > > > > > > > > > > > > > Yeah, it looks like that skl.c keeps the display power on by assuming > > > > > > > that it's turned off by the codec driver, but it doesn't happen > > > > > > > actually. I also find it fishy there... > > > > > > > > > > > > > > > > > > > snd_hdac_display_power is called intentionally to ensure that the codec is > > > > > > powered up before any communication is initiated from either skl.c or > > > > > > hdac_hdmi.c. > > > > > > > > > > But who turns it down if the device is not used? > > > > > > > > Powering down of codec is taken care in codec's suspend routine. > > > > > > But you'll power up twice, no? Once in skl_resume() (which is no > > > runtime resume but only for S3/S4) and once in codec resume. > > > I wonder who will turn down when you wake up from S3. > > > > No. When entering to S3, hdmi_codec_prepare() will invoke the runtime > > resume of codec hdac_hdmi_runtime_resume() which power up the codec and > > skl_suspend power down the codec. When it wakes up from S3, skl_resume() > > powers up the codec and hdmi_codec_complete invokes the runtime suspend of > > codec hdac_hdmi_runtime_suspend() which powers down the codec. > > Hm, but what about the i915 power well refcount, not the codec runtime > PM refcount? Does the refcount reach to zero when the system goes to > runtime suspend? That puzzles me. > Yes, i915 power well refcount goes to zero when system goes to runtime suspend. The value of bus->i915_power_refcount in snd_hdac_display_power is zero. > > This design is required to achieve the runtime power reference count for > > codec device when it is put to S3/S4 while playback was going on. > > ... and this "design" picture is completely missing. > That's why illustrating it was requested instead of a patch :) > > > > The runtime > > > suspend doesn't call snd_hdac_display_power() in skl.c. > > > > > > > Display power management for all runtime uses cases are handled in the > > codec driver hdac_hdmi.c. > > But it means that hdac_hdmi.c does manage the extra decrement the > refcount that was taken in skl.c? > No, snd_hdac_display_power is invoked in skl.c for the following cases, skl_probe_work - display power on, enumurate the codec and display power off skl_suspend & skl_resume - display power off/on for S3/S0 cycle respectively snd_hdac_display_power is invoked in hdac_hdmi.c for the following cases, hdac_hdmi_dev_probe - display power on, probe the device and put the device to runtime suspend explicitly runtime suspend & resume - display power off and on respectively Thanks, Sriram.