ALSA: hda: Use waitqueue for RIRB in HDA-core helper, too (89698ed5) · Commits · 戴 / test

This patch implements the same logic that was done for the legacy HD-audio controller driver by the commit ("ALSA: hda: Use standard waitqueue for RIRB wakeup") to the HDA-core helper code, too. This makes snd_hdac_bus_get_response() waiting for the response with bus->rirb_wq instead of polling when bus->polling is false. It'll save both CPU time and response latency. Reviewed-by:

Kai Vehmanen <kai.vehmanen@linux.intel.com> Link: https://lore.kernel.org/r/20191212191101.19517-2-tiwai@suse.de Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/hda/hdac_controller.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -241,30 +241,42 @@ int snd_hdac_bus_get_response(struct hdac_bus *bus, unsigned int addr,
		{
		unsigned long timeout;
		unsigned long loopcounter;
		wait_queue_entry_t wait;

		init_wait_entry(&wait, 0);
		timeout = jiffies + msecs_to_jiffies(1000);

		for (loopcounter = 0;; loopcounter++) {
		spin_lock_irq(&bus->reg_lock);
		if (!bus->polling_mode)
		prepare_to_wait(&bus->rirb_wq, &wait,
		TASK_UNINTERRUPTIBLE);
		if (bus->polling_mode)
		snd_hdac_bus_update_rirb(bus);
		if (!bus->rirb.cmds[addr]) {
		if (res)
		res = bus->rirb.res[addr]; / the last value */
		if (!bus->polling_mode)
		finish_wait(&bus->rirb_wq, &wait);
		spin_unlock_irq(&bus->reg_lock);
		return 0;
		}
		spin_unlock_irq(&bus->reg_lock);
		if (time_after(jiffies, timeout))
		break;
		if (loopcounter > 3000)
		if (!bus->polling_mode) {
		schedule_timeout(msecs_to_jiffies(2));
		} else if (loopcounter > 3000) {
		msleep(2); /* temporary workaround */
		else {
		} else {
		udelay(10);
		cond_resched();
		}
		}

		if (!bus->polling_mode)
		finish_wait(&bus->rirb_wq, &wait);

		return -EIO;
		}
		EXPORT_SYMBOL_GPL(snd_hdac_bus_get_response);

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