V4L/DVB (10278): cx18: Fix bad audio in first analog capture.

Normalize the APU state before the second firmware load so that audio
for the first analog capture is correct.

Many thanks to Conexant for supporting me in finding a solution for this
problem.

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

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

@@ -1043,8 +1043,21 @@ int cx18_init_on_first_open(struct cx18 *cx)
 	}
 	set_bit(CX18_F_I_LOADED_FW, &cx->i_flags);
 
-	/* Init the firmware twice to work around a silicon bug
-	 * transport related. */
+	/*
+	 * Init the firmware twice to work around a silicon bug
+	 * with the digital TS.
+	 *
+	 * The second firmware load requires us to normalize the APU state,
+	 * or the audio for the first analog capture will be badly incorrect.
+	 *
+	 * I can't seem to call APU_RESETAI and have it succeed without the
+	 * APU capturing audio, so we start and stop it here to do the reset
+	 */
+
+	/* MPEG Encoding, 224 kbps, MPEG Layer II, 48 ksps */
+	cx18_vapi(cx, CX18_APU_START, 2, CX18_APU_ENCODING_METHOD_MPEG|0xb9, 0);
+	cx18_vapi(cx, CX18_APU_RESETAI, 0);
+	cx18_vapi(cx, CX18_APU_STOP, 1, CX18_APU_ENCODING_METHOD_MPEG);
 
 	fw_retry_count = 3;
 	while (--fw_retry_count > 0) {

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

@@ -83,6 +83,8 @@ static const struct cx18_api_info api_info[] = {
 	API_ENTRY(CPU, CX18_CPU_DE_SET_MDL_ACK,			0),
 	API_ENTRY(CPU, CX18_CPU_DE_SET_MDL,			API_FAST),
 	API_ENTRY(CPU, CX18_CPU_DE_RELEASE_MDL,			API_SLOW),
+	API_ENTRY(APU, CX18_APU_START,				0),
+	API_ENTRY(APU, CX18_APU_STOP,				0),
 	API_ENTRY(APU, CX18_APU_RESETAI,			0),
 	API_ENTRY(CPU, CX18_CPU_DEBUG_PEEK32,			0),
 	API_ENTRY(0, 0,						0),

drivers/media/video/cx18/cx23418.h

@@ -56,6 +56,22 @@
 #define APU_CMD_MASK 				0x10000000
 #define APU_CMD_MASK_ACK 			(APU_CMD_MASK | 0x80000000)
 
+#define CX18_APU_ENCODING_METHOD_MPEG		(0 << 28)
+#define CX18_APU_ENCODING_METHOD_AC3		(1 << 28)
+
+/* Description: Command APU to start audio
+   IN[0] - audio parameters (same as CX18_CPU_SET_AUDIO_PARAMETERS?)
+   IN[1] - caller buffer address, or 0
+   ReturnCode - ??? */
+#define CX18_APU_START				(APU_CMD_MASK | 0x01)
+
+/* Description: Command APU to stop audio
+   IN[0] - encoding method to stop
+   ReturnCode - ??? */
+#define CX18_APU_STOP				(APU_CMD_MASK | 0x02)
+
+/* Description: Command APU to reset the AI
+   ReturnCode - ??? */
 #define CX18_APU_RESETAI 			(APU_CMD_MASK | 0x05)
 
 /* Description: This command indicates that a Memory Descriptor List has been