V4L/DVB (4504): Enable audio DMA restart on channel change even when cx88-alsa is compiled

cx88-alsa can be compiled in (in distro built kernels, for example), but
not used. In those cases, the audio DMA restart is needed for proper sound
on NICAM channels.
This patch enables the DMA restart even with ALSA, but the functions now
check if cx88-alsa is really active.

Signed-off-by: Ricardo Cerqueira <v4l@cerqueira.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/cx88/cx88-core.c

@@ -792,6 +792,11 @@ int cx88_start_audio_dma(struct cx88_core *core)
 {
 	/* constant 128 made buzz in analog Nicam-stereo for bigger fifo_size */
 	int bpl = cx88_sram_channels[SRAM_CH25].fifo_size/4;
+
+	/* If downstream RISC is enabled, bail out; ALSA is managing DMA */
+	if (cx_read(MO_AUD_DMACNTRL) & 0x10)
+		return 0;
+
 	/* setup fifo + format */
 	cx88_sram_channel_setup(core, &cx88_sram_channels[SRAM_CH25], bpl, 0);
 	cx88_sram_channel_setup(core, &cx88_sram_channels[SRAM_CH26], bpl, 0);
@@ -801,11 +806,16 @@ int cx88_start_audio_dma(struct cx88_core *core)
 
 	/* start dma */
 	cx_write(MO_AUD_DMACNTRL, 0x0003); /* Up and Down fifo enable */
+
 	return 0;
 }
 
 int cx88_stop_audio_dma(struct cx88_core *core)
 {
+	/* If downstream RISC is enabled, bail out; ALSA is managing DMA */
+	if (cx_read(MO_AUD_DMACNTRL) & 0x10)
+		return 0;
+
 	/* stop dma */
 	cx_write(MO_AUD_DMACNTRL, 0x0000);
 

drivers/media/video/cx88/cx88-tvaudio.c

@@ -137,14 +137,10 @@ static void set_audio_finish(struct cx88_core *core, u32 ctl)
 {
 	u32 volume;
 
-#ifndef CONFIG_VIDEO_CX88_ALSA
 	/* restart dma; This avoids buzz in NICAM and is good in others  */
 	cx88_stop_audio_dma(core);
-#endif
 	cx_write(AUD_RATE_THRES_DMD, 0x000000C0);
-#ifndef CONFIG_VIDEO_CX88_ALSA
 	cx88_start_audio_dma(core);
-#endif
 
 	if (cx88_boards[core->board].blackbird) {
 		/* sets sound input from external adc */