Hi Takashi,
Thanks again for your clarification and patch! Will these two patches enter sound.git or sound-unstable.git at the moment?
Regards Mengdong
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Monday, December 02, 2013 6:19 PM To: Lin, Mengdong Cc: David Henningsson; alsa-devel@alsa-project.org Subject: Re: [alsa-devel] HD-Audio: How to reduce driver initializaton time if multiple codecs present on the bus?
At Mon, 02 Dec 2013 10:52:00 +0100, Takashi Iwai wrote:
At Mon, 2 Dec 2013 09:48:24 +0000, Lin, Mengdong wrote:
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Monday, December 02, 2013 4:24 PM
> > > Btw, using a deferred azx_probe_continue (like we do if > > > there's a firmware file), would one get more > > > parallelization with
other drivers?
> > > If so we could consider making that the default. > > > > This sounds like a good idea as we have already that code. > > The patch would be just a few-liners. > > If azx_probe_continue() is delayed, could user space get > incomplete audio information after boot? > I mean is it possible that azx_probe_continue() does not > complete before user space check ALSA info?
Not impossible. But then user-space should be triggered in event driven way by udev or such.
Hi Takashi/David,
So is it okay to defer azx_probe_continue() by default?
Yes.
If yes, is it also necessary to defer snd_card_create() at the end of
azx_probe_continue()?
No, that's a significant difference. The snd_card_create() invocation isn't related with the hardware access itself, thus it's no point to delay. If you delay the card instance creation, this may result in races between the card order, which we'd like to
avoid.
So user space can only see the sound card when azx_probe_continue()
completes.
The completion of the card creation is notified only after snd_card_register(), so it doesn't matter when to call
snd_card_create().
The below is an untested patch. I should have added in the previous reply...
Hi Takashi,
Many thanks for the patch and information!
Is my understanding below is right? snd_card_register() will create the device files under /sys/devices/pci0000:00/0000:00:1b.0/sound/cardx (or /sys/devices/pci0000:00/0000:00:03.0/sound/cardx for Haswell
display audio), and trigger uevent to notify user space that an audio device is ready.
And for the patch,
Yes.
#ifdef CONFIG_SND_HDA_PATCH_LOADER if (patch[dev] && *patch[dev]) { @@ -3855,25 +3855,17 @@
static
int azx_probe(struct pci_dev *pci, azx_firmware_cb); if (err < 0) goto out_free;
probe_now = false; /* continued in azx_firmware_cb() */
schedule_probe = false; /* continued in azx_firmware_cb()*/
}
Should it be 'schedule_probe = true'? I guess the driver intends to defer firmware loading.
No, in the case of f/w loading, f/w loader itself calls azx_probe_continue(), thus you don't need to schedule it manually.
We may move the f/w loading into azx_probe_continue() for simplicity, though, after applying the always-deferred-probe patch. Then it can be back to request_firmware() again (not _nowait()).
BTW, while checking my previous patch, I noticed that the complete_all() should be put in the delayed probe part, too. The following patch fixes it.
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: hda - Fix complete_all() timing in deferred probes
When the probe of snd-hda-intel driver is deferred due to f/w loading or the nested module loading, complete_all() should be also delayed until the initialization really finished. Otherwise, vga-switcheroo client would start switching before the actual init is done.
Signed-off-by: Takashi Iwai tiwai@suse.de
sound/pci/hda/hda_intel.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index c6d230193da6..27aa14007cbd 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -3876,7 +3876,8 @@ static int azx_probe(struct pci_dev *pci, }
dev++;
- complete_all(&chip->probe_wait);
- if (chip->disabled)
complete_all(&chip->probe_wait);out_free: @@ -3953,10 +3954,10 @@ static int azx_probe_continue(struct azx *chip) if ((chip->driver_caps & AZX_DCAPS_PM_RUNTIME) || chip->use_vga_switcheroo) pm_runtime_put_noidle(&pci->dev);
- return 0;
out_free:
- chip->init_failed = 1;
- if (err < 0)
chip->init_failed = 1;- complete_all(&chip->probe_wait); return err;
}
-- 1.8.4.4