V4L/DVB (11624): cx18: Toggle the AI1 mux when changing the CX18_AUDIO_ENABLE register

Toggle the AI1 mux when changing the CX18_AUDIO_ENABLE register.  It's hard to
reliably tell when we have written to this register successfully unless we
change some bits we know we can read back.  The AI mux bits always read back
what we wrote to them, so force them to toggle whenever we have to write to
the register, so we can tell we wrote to the register successfully.

This change was prompted by users experiencing broadcast audio decoding
problems after the cx18 module loads for the first time.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-audio.c

@@ -26,14 +26,18 @@
 #include "cx18-cards.h"
 #include "cx18-audio.h"
 
-#define CX18_AUDIO_ENABLE 0xc72014
+#define CX18_AUDIO_ENABLE    0xc72014
+#define CX18_AI1_MUX_MASK    0x30
+#define CX18_AI1_MUX_I2S1    0x00
+#define CX18_AI1_MUX_I2S2    0x10
+#define CX18_AI1_MUX_843_I2S 0x20
 
 /* Selects the audio input and output according to the current
    settings. */
 int cx18_audio_set_io(struct cx18 *cx)
 {
 	const struct cx18_card_audio_input *in;
-	u32 val;
+	u32 u, v;
 	int err;
 
 	/* Determine which input to use */
@@ -52,9 +56,37 @@ int cx18_audio_set_io(struct cx18 *cx)
 		return err;
 
 	/* FIXME - this internal mux should be abstracted to a subdev */
-	val = cx18_read_reg(cx, CX18_AUDIO_ENABLE) & ~0x30;
-	val |= (in->audio_input > CX18_AV_AUDIO_SERIAL2) ? 0x20 :
-					(in->audio_input << 4);
-	cx18_write_reg_expect(cx, val | 0xb00, CX18_AUDIO_ENABLE, val, 0x30);
+	u = cx18_read_reg(cx, CX18_AUDIO_ENABLE);
+	v = u & ~CX18_AI1_MUX_MASK;
+	switch (in->audio_input) {
+	case CX18_AV_AUDIO_SERIAL1:
+		v |= CX18_AI1_MUX_I2S1;
+		break;
+	case CX18_AV_AUDIO_SERIAL2:
+		v |= CX18_AI1_MUX_I2S2;
+		break;
+	default:
+		v |= CX18_AI1_MUX_843_I2S;
+		break;
+	}
+	if (v == u) {
+		/* force a toggle of some AI1 MUX control bits */
+		u &= ~CX18_AI1_MUX_MASK;
+		switch (in->audio_input) {
+		case CX18_AV_AUDIO_SERIAL1:
+			u |= CX18_AI1_MUX_843_I2S;
+			break;
+		case CX18_AV_AUDIO_SERIAL2:
+			u |= CX18_AI1_MUX_843_I2S;
+			break;
+		default:
+			u |= CX18_AI1_MUX_I2S1;
+			break;
+		}
+		cx18_write_reg_expect(cx, u | 0xb00, CX18_AUDIO_ENABLE,
+				      u, CX18_AI1_MUX_MASK);
+	}
+	cx18_write_reg_expect(cx, v | 0xb00, CX18_AUDIO_ENABLE,
+			      v, CX18_AI1_MUX_MASK);
 	return 0;
 }

drivers/media/video/cx18/cx18-av-firmware.c

@@ -24,7 +24,13 @@
 #include "cx18-io.h"
 #include <linux/firmware.h>
 
-#define CX18_AUDIO_ENABLE 0xc72014
+#define CX18_AUDIO_ENABLE    0xc72014
+#define CX18_AI1_MUX_MASK    0x30
+#define CX18_AI1_MUX_I2S1    0x00
+#define CX18_AI1_MUX_I2S2    0x10
+#define CX18_AI1_MUX_843_I2S 0x20
+#define CX18_AI1_MUX_INVALID 0x30
+
 #define FWFILE "v4l-cx23418-dig.fw"
 
 static int cx18_av_verifyfw(struct cx18 *cx, const struct firmware *fw)
@@ -74,7 +80,7 @@ int cx18_av_loadfw(struct cx18 *cx)
 	struct v4l2_subdev *sd = &cx->av_state.sd;
 	const struct firmware *fw = NULL;
 	u32 size;
-	u32 v;
+	u32 u, v;
 	const u8 *ptr;
 	int i;
 	int retries1 = 0;
@@ -183,6 +189,28 @@ int cx18_av_loadfw(struct cx18 *cx)
 		cx18_write_reg_expect(cx, v & 0xFFFFFBFF, CX18_AUDIO_ENABLE,
 				      0, 0x400);
 
+	/* Toggle the AI1 MUX */
+	v = cx18_read_reg(cx, CX18_AUDIO_ENABLE);
+	u = v & CX18_AI1_MUX_MASK;
+	v &= ~CX18_AI1_MUX_MASK;
+	if (u == CX18_AI1_MUX_843_I2S || u == CX18_AI1_MUX_INVALID) {
+		/* Switch to I2S1 */
+		v |= CX18_AI1_MUX_I2S1;
+		cx18_write_reg_expect(cx, v | 0xb00, CX18_AUDIO_ENABLE,
+				      v, CX18_AI1_MUX_MASK);
+		/* Switch back to the A/V decoder core I2S output */
+		v = (v & ~CX18_AI1_MUX_MASK) | CX18_AI1_MUX_843_I2S;
+	} else {
+		/* Switch to the A/V decoder core I2S output */
+		v |= CX18_AI1_MUX_843_I2S;
+		cx18_write_reg_expect(cx, v | 0xb00, CX18_AUDIO_ENABLE,
+				      v, CX18_AI1_MUX_MASK);
+		/* Switch back to I2S1 or I2S2 */
+		v = (v & ~CX18_AI1_MUX_MASK) | u;
+	}
+	cx18_write_reg_expect(cx, v | 0xb00, CX18_AUDIO_ENABLE,
+			      v, CX18_AI1_MUX_MASK);
+
 	/* Enable WW auto audio standard detection */
 	v = cx18_av_read4(cx, CXADEC_STD_DET_CTL);
 	v |= 0xFF;   /* Auto by default */