1 files changed, 16 insertions, 2 deletions

diff --git a/firmware/drivers/tuner/rda5802.c b/firmware/drivers/tuner/rda5802.c
index 377bdd1e6f..3f122714bd 100644
--- a/firmware/drivers/tuner/rda5802.c
+++ b/firmware/drivers/tuner/rda5802.c
@@ -42,6 +42,7 @@
 #define RSSI_MAX 70
 
 /** Registers and bits **/
+#define CHIPID      0x0
 #define POWERCFG    0x2
 #define CHANNEL     0x3
 #define SYSCONFIG1  0x4
@@ -52,7 +53,6 @@
 #define SYSCONFIG6  0x9 /* undocumented */
 #define READCHAN    0xA
 #define STATUSRSSI  0xB
-#define IDENT       0xC
 
 
 /* POWERCFG (0x2) */
@@ -190,7 +190,21 @@ static void rda5802_sleep(int snooze)
 
 bool rda5802_detect(void)
 {
-    return ((rda5802_read_reg(IDENT) & 0xFF00) == 0x5800);
+    /* The RDA5802 has a weird wrap-around at 0x40. Upon initialisation, it will copy the Chip ID
+     * to register 0xC but since this register is also used for RDS, we cannot rely on its content
+     * until we softreset. But we cannot soft-reset until we confirm the tuner type... So we really
+     * need to register 0, which means reading 0x40 registers.
+     * NOTE: the datasheet says that it wraps around at 0x3A but this is wrong. */
+
+    /* we want to read registers 0x00/0x01, aka 0x40/0x41 because of wrapping, tuner starts reading
+     * at 0xA so we need to read 0x40 - 0xA + 2 registers, each register is two bytes. Thats
+     * (0x40 - 0xA + 2) * 2 = 0x6e bytes */
+    unsigned char buf[0x70];
+    fmradio_i2c_read(I2C_ADR, buf, sizeof(buf));
+    cache[CHIPID] = buf[0x6c] << 8 | buf[0x6d];
+    cache[1] = buf[0x6e] << 8 | buf[0x6f]; /* unknown register, maybe firmware ID or related */
+
+    return ((cache[CHIPID] & 0xFF00) == 0x5800);
  }
 
 void rda5802_init(void)