Re: HD-Audio: How to reduce driver initializaton time if multiple codecs present on the bus?

[Takashi Iwai <tiwai@suse.de>]

At Mon, 02 Dec 2013 13:18:11 +0100,
Takashi Iwai wrote:
> 
> At Mon, 2 Dec 2013 11:27:55 +0000,
> Lin, Mengdong wrote:
> > 
> > Hi Takashi,
> > 
> > Thanks again for your clarification and patch!
> > Will these two patches enter sound.git or sound-unstable.git at the moment?
> 
> Yes, I'm going to merge them unless anyone finds problems.

Turned out the original patch leading to a build error depending on
kconfig.  Below is the fixed version.


Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH] ALSA: hda - Always do delayed probes for HD-audio devices

HD-audio devices tend to take long time for finishing the whole
probing procedure.  In this patch, the time-consuming part of the
probing procedure, the codec probe and the rest initializations, are
moved in the work, so that they can be done asynchronously in parallel
with probes of other devices.

Since we already have this mechanism in the driver code for the
firmware and i915 request_symbol() stuff, we just need to enable it
always; the resultant patch even reduces more lines, which is an
additional bonus.

Credit goes to David Henningsson, who suggested this workaround.

Reported-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/pci/hda/hda_intel.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 486d25fa7e97..80c5f14e8ecd 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -543,9 +543,7 @@ struct azx {
 	/* for pending irqs */
 	struct work_struct irq_pending_work;
 
-#ifdef CONFIG_SND_HDA_I915
 	struct work_struct probe_work;
-#endif
 
 	/* reboot notifier (for mysterious hangup problem at power-down) */
 	struct notifier_block reboot_notifier;
@@ -3500,12 +3498,10 @@ static void azx_check_snoop_available(struct azx *chip)
 	}
 }
 
-#ifdef CONFIG_SND_HDA_I915
 static void azx_probe_work(struct work_struct *work)
 {
 	azx_probe_continue(container_of(work, struct azx, probe_work));
 }
-#endif
 
 /*
  * constructor
@@ -3582,10 +3578,8 @@ static int azx_create(struct snd_card *card, struct pci_dev *pci,
 		return err;
 	}
 
-#ifdef CONFIG_SND_HDA_I915
 	/* continue probing in work context as may trigger request module */
 	INIT_WORK(&chip->probe_work, azx_probe_work);
-#endif
 
 	*rchip = chip;
 
@@ -3805,7 +3799,7 @@ static int azx_probe(struct pci_dev *pci,
 	static int dev;
 	struct snd_card *card;
 	struct azx *chip;
-	bool probe_now;
+	bool schedule_probe;
 	int err;
 
 	if (dev >= SNDRV_CARDS)
@@ -3844,7 +3838,7 @@ static int azx_probe(struct pci_dev *pci,
 		chip->disabled = true;
 	}
 
-	probe_now = !chip->disabled;
+	schedule_probe = !chip->disabled;
 
 #ifdef CONFIG_SND_HDA_PATCH_LOADER
 	if (patch[dev] && *patch[dev]) {
@@ -3855,25 +3849,17 @@ 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() */
 	}
 #endif /* CONFIG_SND_HDA_PATCH_LOADER */
 
-	/* continue probing in work context, avoid request_module deadlock */
-	if (probe_now && (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)) {
-#ifdef CONFIG_SND_HDA_I915
-		probe_now = false;
-		schedule_work(&chip->probe_work);
-#else
+#ifndef CONFIG_SND_HDA_I915
+	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
 		snd_printk(KERN_ERR SFX "Haswell must build in CONFIG_SND_HDA_I915\n");
 #endif
-	}
 
-	if (probe_now) {
-		err = azx_probe_continue(chip);
-		if (err < 0)
-			goto out_free;
-	}
+	if (schedule_probe)
+		schedule_work(&chip->probe_work);
 
 	dev++;
 	if (chip->disabled)
-- 
1.8.4.4