Hi Takashi,
>> >
>> >On Fri, 22 Mar 2019 07:24:56 +0100,
>> >libin.yang@xxxxxxxxx wrote:
>> >>
>> >> From: Libin Yang <libin.yang@xxxxxxxxx>
>> >>
>> >> In S3, there is a contest between dapm event and getting display power.
>> >>
>> >> When resume, the sequence is:
>> >>
>> >> hdac_hdmi_runtime_resume()
>> >> => snd_hdac_display_power()
>> >> hdac_hdmi_xxx_widget_event()
>> >>
>> >> The hdac_hdmi_xxx_widget_event() are based on the power being on.
>> >> Otherwise, the operation on the codec register will fail.
>> >>
>> >> However, in snd_hdac_display_power(), it may sleep because of the
>> >> mutex_lock() in display driver. In this case,
>> >> hdac_hdmi_xxx_widget_event() will be called before the power is on.
>> >>
>> >> Let's not operate the registers and wait for the power in
>> >> hdac_hdmi_xxx_widget_event()
>> >>
>> >> Signed-off-by: Libin Yang <libin.yang@xxxxxxxxx>
>> >
>> >IMO the workaround looks a bit too fragile. The substantial problem
>> >is the race between codec and DAPM. Can this be controlled better,
>> >e.g. by defining the proper PM dependency? I thought we may
>> >rearrange the PM topology dynamically.
>>
>> It seems codec and DAPM is OK so far. Codec resume will be called
>> firstly and then DAPM. But in HDMI codec runtime resume, it will call
>> snd_hdac_display_power(). This function will try to get a mutex_lock.
>> If it fails to get the lock, it will sleep. This will cause dapm event
>> handler to be called before audio power domain in display is on in the HDMI
>driver.
>
>It implies that the calls are racy. If they have to be called in some order, they
>have to be serialized in a more better way than inserting a random delay...
Yes. The code does seem to be misleading. What do you think of using
something like "wait_for_complete()"? This will be more readable.
Regards,
Libin
>
>
>thanks,
>
>Takashi
>
>>
>> Regards,
>> Libin
>>
>> >
>> >
>> >thanks,
>> >
>> >Takashi
>> >
>> >> ---
>> >> sound/soc/codecs/hdac_hdmi.c | 36
>> >> ++++++++++++++++++++++++++++++++++++
>> >> 1 file changed, 36 insertions(+)
>> >>
>> >> diff --git a/sound/soc/codecs/hdac_hdmi.c
>> >> b/sound/soc/codecs/hdac_hdmi.c index 5eeb0fe..3c5c122 100644
>> >> --- a/sound/soc/codecs/hdac_hdmi.c
>> >> +++ b/sound/soc/codecs/hdac_hdmi.c
>> >> @@ -144,6 +144,7 @@ struct hdac_hdmi_priv {
>> >> int num_pin;
>> >> int num_cvt;
>> >> int num_ports;
>> >> + int display_power; /* 0: power off; 1 power on */
>> >> struct mutex pin_mutex;
>> >> struct hdac_chmap chmap;
>> >> struct hdac_hdmi_drv_data *drv_data; @@ -742,12 +743,27 @@
>> >static
>> >> void hdac_hdmi_set_amp(struct hdac_device *hdev,
>> >> AC_VERB_SET_AMP_GAIN_MUTE,
>> >val); }
>> >>
>> >> +static int wait_for_display_power(struct hdac_hdmi_priv *hdmi) {
>> >> + int i = 0;
>> >> +
>> >> + /* sleep for totally 80ms ~ 200ms should be enough */
>> >> + while (i < 40) {
>> >> + if (!hdmi->display_power)
>> >> + usleep_range(2000, 5000);
>> >> + else
>> >> + return 0;
>> >> + i++;
>> >> + }
>> >> + return -EAGAIN;
>> >> +}
>> >>
>> >> static int hdac_hdmi_pin_output_widget_event(struct
>> >snd_soc_dapm_widget *w,
>> >> struct snd_kcontrol *kc, int event) {
>> >> struct hdac_hdmi_port *port = w->priv;
>> >> struct hdac_device *hdev = dev_to_hdac_dev(w->dapm->dev);
>> >> + struct hdac_hdmi_priv *hdmi = hdev_to_hdmi_priv(hdev);
>> >> struct hdac_hdmi_pcm *pcm;
>> >>
>> >> dev_dbg(&hdev->dev, "%s: widget: %s event: %x\n", @@ -757,6
>> >+773,11
>> >> @@ static int hdac_hdmi_pin_output_widget_event(struct
>> >snd_soc_dapm_widget *w,
>> >> if (!pcm)
>> >> return -EIO;
>> >>
>> >> + if (wait_for_display_power(hdmi)) {
>> >> + dev_err(&hdev->dev, "%s: hdmi power is not ready\n",
>> >__func__);
>> >> + return -EAGAIN;
>> >> + }
>> >> +
>> >> /* set the device if pin is mst_capable */
>> >> if (hdac_hdmi_port_select_set(hdev, port) < 0)
>> >> return -EIO;
>> >> @@ -803,6 +824,11 @@ static int
>> >hdac_hdmi_cvt_output_widget_event(struct snd_soc_dapm_widget *w,
>> >> if (!pcm)
>> >> return -EIO;
>> >>
>> >> + if (wait_for_display_power(hdmi)) {
>> >> + dev_err(&hdev->dev, "%s: hdmi power is not ready\n",
>> >__func__);
>> >> + return -EAGAIN;
>> >> + }
>> >> +
>> >> switch (event) {
>> >> case SND_SOC_DAPM_PRE_PMU:
>> >> hdac_hdmi_set_power_state(hdev, cvt->nid, AC_PWRST_D0);
>> >@@ -840,6
>> >> +866,7 @@ static int hdac_hdmi_pin_mux_widget_event(struct
>> >> snd_soc_dapm_widget *w, {
>> >> struct hdac_hdmi_port *port = w->priv;
>> >> struct hdac_device *hdev = dev_to_hdac_dev(w->dapm->dev);
>> >> + struct hdac_hdmi_priv *hdmi = hdev_to_hdmi_priv(hdev);
>> >> int mux_idx;
>> >>
>> >> dev_dbg(&hdev->dev, "%s: widget: %s event: %x\n", @@ -850,6
>> >+877,11
>> >> @@ static int hdac_hdmi_pin_mux_widget_event(struct
>> >> snd_soc_dapm_widget *w,
>> >>
>> >> mux_idx = dapm_kcontrol_get_value(kc);
>> >>
>> >> + if (wait_for_display_power(hdmi)) {
>> >> + dev_err(&hdev->dev, "%s: hdmi power is not ready\n",
>> >__func__);
>> >> + return -EAGAIN;
>> >> + }
>> >> +
>> >> /* set the device if pin is mst_capable */
>> >> if (hdac_hdmi_port_select_set(hdev, port) < 0)
>> >> return -EIO;
>> >> @@ -2068,6 +2100,7 @@ static int hdac_hdmi_runtime_suspend(struct
>> >> device *dev) {
>> >> struct hdac_device *hdev = dev_to_hdac_dev(dev);
>> >> struct hdac_bus *bus = hdev->bus;
>> >> + struct hdac_hdmi_priv *hdmi = hdev_to_hdmi_priv(hdev);
>> >> struct hdac_ext_link *hlink = NULL;
>> >>
>> >> dev_dbg(dev, "Enter: %s\n", __func__); @@ -2095,6 +2128,7 @@
>> >static
>> >> int hdac_hdmi_runtime_suspend(struct device *dev)
>> >> snd_hdac_ext_bus_link_put(bus, hlink);
>> >>
>> >> snd_hdac_display_power(bus, hdev->addr, false);
>> >> + hdmi->display_power = 0;
>> >>
>> >> return 0;
>> >> }
>> >> @@ -2102,6 +2136,7 @@ static int hdac_hdmi_runtime_suspend(struct
>> >> device *dev) static int hdac_hdmi_runtime_resume(struct device
>> >> *dev) {
>> >> struct hdac_device *hdev = dev_to_hdac_dev(dev);
>> >> + struct hdac_hdmi_priv *hdmi = hdev_to_hdmi_priv(hdev);
>> >> struct hdac_bus *bus = hdev->bus;
>> >> struct hdac_ext_link *hlink = NULL;
>> >>
>> >> @@ -2128,6 +2163,7 @@ static int hdac_hdmi_runtime_resume(struct
>> >device *dev)
>> >> snd_hdac_codec_read(hdev, hdev->afg, 0,
>> > AC_VERB_SET_POWER_STATE,
>> >> AC_PWRST_D0);
>> >>
>> >> + hdmi->display_power = 1;
>> >> return 0;
>> >> }
>> >> #else
>> >> --
>> >> 2.7.4
>> >>
>> >> _______________________________________________
>> >> Alsa-devel mailing list
>> >> Alsa-devel@xxxxxxxxxxxxxxxx
>> >> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>> >>
>>
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
