On Wed, 2009-08-19 at 14:05 +0200, Takashi Iwai wrote:
At Wed, 19 Aug 2009 18:59:31 +0800, Shine Liu wrote:
On Wed, 2009-08-19 at 12:34 +0200, Takashi Iwai wrote:
At Wed, 19 Aug 2009 18:22:19 +0800, Shine Liu wrote:
There's no restriction on that the runtime->period_size should be the multiplicator of the runtime->buffer_size in current kernel code.
So "hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;" is not always the trueth.
The hw_ptr_interrupt is the expected position where the current irq is issued. So, the current code should be correct -- it's simply increased in the size of period_size.
Yes, the period_size and buffer_size I used was 0x800 and 0x3e80.
The log from the kernel is :
period_update: pcmC0D0p:0: pos=0x809/0x800/0x3e80, hwptr=0x1c, hw_base=0x0, hw_intr=0x0 period_update: pcmC0D0p:0: pos=0x1008/0x800/0x3e80, hwptr=0x809, hw_base=0x0, hw_intr=0x800 period_update: pcmC0D0p:0: pos=0x1808/0x800/0x3e80, hwptr=0x10e3, hw_base=0x0, hw_intr=0x1000 period_update: pcmC0D0p:0: pos=0x2006/0x800/0x3e80, hwptr=0x1808, hw_base=0x0, hw_intr=0x1800 period_update: pcmC0D0p:0: pos=0x2808/0x800/0x3e80, hwptr=0x203f, hw_base=0x0, hw_intr=0x2000 period_update: pcmC0D0p:0: pos=0x3008/0x800/0x3e80, hwptr=0x2808, hw_base=0x0, hw_intr=0x2800 period_update: pcmC0D0p:0: pos=0x3808/0x800/0x3e80, hwptr=0x30e9, hw_base=0x0, hw_intr=0x3000 period_update: pcmC0D0p:0: pos=0x8/0x800/0x3e80, hwptr=0x3808, hw_base=0x0, hw_intr=0x3800 PCM: Unexpected hw_pointer value (stream=0, pos=8, intr_ptr=16384)
It's true that irq was issued when hw_ptr_interrupt is 0x800,0x1000,0x1800,...,0x3800,0x3e80.
But the irq last issued should be at 0x3e80, but not 0x3800 + 0x800 = 0x4000. The DMA engine loaded 0x680 frame not 0x800 frame at the last time.
Then it's a driver bug. If unaligned period size is allowed, it means that the irq is really generated in that period, not at the buffer boundary. Otherwise, it must have a proper hw-constraint to align the period size to the buffer size.
What hardware is it?
thanks,
Takashi
This patch will fix the bug metioned in the above mail. Force the peroid size to be aligned with the buffer size.
Based and tested on linux-2.6.31-rc6.
Signed-off-by: Shine Liu shinel@foxmail.com ---------------------------------------------------------------------------
--- a/sound/soc/s3c24xx/s3c24xx-pcm.c 2009-08-14 06:43:34.000000000 +0800 +++ b/sound/soc/s3c24xx/s3c24xx-pcm.c 2009-08-20 22:33:58.000000000 +0800 @@ -318,6 +318,7 @@
pr_debug("Entered %s\n", __func__);
+ snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); snd_soc_set_runtime_hwparams(substream, &s3c24xx_pcm_hardware);
prtd = kzalloc(sizeof(struct s3c24xx_runtime_data), GFP_KERNEL);