Fix OSS driver doesn't respect O_NONBLOCK when recording

This patch added a variable to mark if data available or not.
Fixed bug 4740.
Signed-off-by: 薛德章 <frank.xue@neuros.com.cn>

sound/oss/davinci-audio-dma-intfc.c

@@ -973,6 +973,7 @@ static void audio_dma_callback(int lch, u16 ch_status, void *data)
 
 		if (!s->mapped) {
 			complete(&s->wfc);
+			s->done_flag = 1;
 		} else
 			s->pending_frags++;
 

sound/oss/davinci-audio.c

@@ -615,7 +615,7 @@ audio_read(struct file *file, char *buffer, size_t count, loff_t * ppos)
 		/* Wait for a buffer to become full */
 		if (file->f_flags & O_NONBLOCK) {
 			ret = -EAGAIN;
-			if (!s->wfc.done)
+			if(!s->done_flag)
 				break;
 		} else {
 			ret = -ERESTARTSYS;
@@ -652,6 +652,7 @@ audio_read(struct file *file, char *buffer, size_t count, loff_t * ppos)
 		DPRINTK(KERN_INFO
 			"calling audio_process_dma from audio_read\n");
 		audio_process_dma(s);
+		s->done_flag = 0;
 	}
 
 	if ((buffer - buffer0))
@@ -1105,6 +1106,7 @@ static int audio_open(struct inode *inode, struct file *file)
 		is->fragsize = AUDIO_FRAGSIZE_DEFAULT;
 		is->nbfrags = AUDIO_NBFRAGS_DEFAULT;
 		is->mapped = 0;
+		is->done_flag = 0;
 		init_waitqueue_head(&is->wq);
 	}
 

sound/oss/davinci-audio.h

@@ -69,6 +69,7 @@ typedef struct {
 	int stopped:1;		/* might be active but stopped */
 	int spin_idle:1;	/* have DMA spin on zeros when idle */
 	int dma_started;	/* to store if DMA was started or not */
+	int done_flag;
 } audio_stream_t;
 
 /*