ALSA: HDA: Lessen CPU usage when waiting for chip to respond
When an IRQ for some reason gets lost, we wait up to a second using udelay, which is CPU intensive. This patch improves the situation by waiting about 30 ms in the CPU intensive mode, then stepping down to using msleep(2) instead. In essence, we trade some granularity in exchange for less CPU consumption when the waiting time is a bit longer. As a result, PulseAudio should no longer be killed by the kernel for taking up to much RT-prio CPU time. At least not for *this* reason. Signed-off-by: David Henningsson <david.henningsson@canonical.com> Tested-by: Arun Raghavan <arun.raghavan@collabora.co.uk> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -783,11 +783,13 @@ static unsigned int azx_rirb_get_response(struct hda_bus *bus,
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{
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struct azx *chip = bus->private_data;
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unsigned long timeout;
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unsigned long loopcounter;
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int do_poll = 0;
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again:
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timeout = jiffies + msecs_to_jiffies(1000);
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for (;;) {
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for (loopcounter = 0;; loopcounter++) {
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if (chip->polling_mode || do_poll) {
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spin_lock_irq(&chip->reg_lock);
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azx_update_rirb(chip);
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@ -803,7 +805,7 @@ static unsigned int azx_rirb_get_response(struct hda_bus *bus,
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}
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if (time_after(jiffies, timeout))
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break;
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if (bus->needs_damn_long_delay)
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if (bus->needs_damn_long_delay || loopcounter > 3000)
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msleep(2); /* temporary workaround */
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else {
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udelay(10);
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