The following commit has been merged in the linux branch: commit e3d8024891dbfec6cf36c9b76177650f48118462 Author: Ben Dooks ben-linux@fluff.org Date: Tue Sep 22 16:48:56 2009 +0100
ARM: S3C: Add info for supporting circular DMA buffers
The S3C64XX DMA implementation will work a lot better with the ability to enqueue circular buffers as the hardware can do it's own linked-list management.
Add a function s3c_dma_has_circular() to show that the system can do this and a flag for the channel.
Update the s3c24xx/s3c64xx I2S DMA code to deal with this.
Signed-off-by: Ben Dooks ben@simtec.co.uk Signed-off-by: Ben Dooks ben-linux@fluff.org Acked-by: Mark Brown <broonie@@opensource.wolfsonmicro.com>
diff --git a/arch/arm/mach-s3c2410/include/mach/dma.h b/arch/arm/mach-s3c2410/include/mach/dma.h index c3a2629..92e2687 100644 --- a/arch/arm/mach-s3c2410/include/mach/dma.h +++ b/arch/arm/mach-s3c2410/include/mach/dma.h @@ -110,6 +110,8 @@ enum s3c2410_dma_loadst { * waiting for reloads */ #define S3C2410_DMAF_AUTOSTART (1<<1) /* auto-start if buffer queued */
+#define S3C2410_DMAF_CIRCULAR (1 << 2) /* no circular dma support */ + /* dma buffer */
struct s3c2410_dma_buf; @@ -194,4 +196,9 @@ struct s3c2410_dma_chan {
typedef unsigned long dma_device_t;
+static inline bool s3c_dma_has_circular(void) +{ + return false; +} + #endif /* __ASM_ARCH_DMA_H */ diff --git a/arch/arm/mach-s3c6400/include/mach/dma.h b/arch/arm/mach-s3c6400/include/mach/dma.h index 1067619..004edab 100644 --- a/arch/arm/mach-s3c6400/include/mach/dma.h +++ b/arch/arm/mach-s3c6400/include/mach/dma.h @@ -68,6 +68,11 @@ static __inline__ int s3c_dma_has_circular(void)
#define S3C2410_DMAF_CIRCULAR (1 << 0)
+static inline bool s3c_dma_has_circular(void) +{ + return false; +} + #include <plat/dma.h>
#endif /* __ASM_ARCH_IRQ_H */ diff --git a/sound/soc/s3c24xx/s3c24xx-pcm.c b/sound/soc/s3c24xx/s3c24xx-pcm.c index 5cbbdc8..1f35c6f 100644 --- a/sound/soc/s3c24xx/s3c24xx-pcm.c +++ b/sound/soc/s3c24xx/s3c24xx-pcm.c @@ -75,11 +75,19 @@ static void s3c24xx_pcm_enqueue(struct snd_pcm_substream *substream) { struct s3c24xx_runtime_data *prtd = substream->runtime->private_data; dma_addr_t pos = prtd->dma_pos; + unsigned int limit; int ret;
pr_debug("Entered %s\n", __func__);
- while (prtd->dma_loaded < prtd->dma_limit) { + if (s3c_dma_has_circular()) { + limit = (prtd->dma_end - prtd->dma_start) / prtd->dma_period; + } else + limit = prtd->dma_limit; + + pr_debug("%s: loaded %d, limit %d\n", __func__, prtd->dma_loaded, limit); + + while (prtd->dma_loaded < limit) { unsigned long len = prtd->dma_period;
pr_debug("dma_loaded: %d\n", prtd->dma_loaded); @@ -123,7 +131,7 @@ static void s3c24xx_audio_buffdone(struct s3c2410_dma_chan *channel, snd_pcm_period_elapsed(substream);
spin_lock(&prtd->lock); - if (prtd->state & ST_RUNNING) { + if (prtd->state & ST_RUNNING && !s3c_dma_has_circular()) { prtd->dma_loaded--; s3c24xx_pcm_enqueue(substream); } @@ -164,6 +172,11 @@ static int s3c24xx_pcm_hw_params(struct snd_pcm_substream *substream, printk(KERN_ERR "failed to get dma channel\n"); return ret; } + + /* use the circular buffering if we have it available. */ + if (s3c_dma_has_circular()) + s3c2410_dma_setflags(prtd->params->channel, + S3C2410_DMAF_CIRCULAR); }
s3c2410_dma_set_buffdone_fn(prtd->params->channel,