ALSA: pcm core - Avoid jiffies check for devices with BATCH flag (3e5b5016) · Commits · 戴 / test

The hardware devices with SNDRV_PCM_INFO_BATCH flag can't give the precise current position. And such hardwares have often big FIFO in addition to the ring buffer, and it screws up the jiffies check in pcm_lib.c. This patch adds a simple check of info flag so that the driver skips the jiffies check in snd_pcm_period_elapsed() when BATCH flag is set. Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/core/pcm_lib.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -249,6 +249,12 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
		new_hw_ptr = hw_base + pos;
		}
		}
		/* Skip the jiffies check for hardwares with BATCH flag.
		* Such hardware usually just increases the position at each IRQ,
		* thus it can't give any strange position.
		*/
		if (runtime->hw.info & SNDRV_PCM_INFO_BATCH)
		goto no_jiffies_check;
		hdelta = new_hw_ptr - old_hw_ptr;
		jdelta = jiffies - runtime->hw_ptr_jiffies;
		if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
		@@ -272,6 +278,7 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
		hw_base -= hw_base % runtime->buffer_size;
		delta = 0;
		}
		no_jiffies_check:
		if (delta > runtime->period_size + runtime->period_size / 2) {
		hw_ptr_error(substream,
		"Lost interrupts? "

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