V4L/DVB (10512): tda1004x: Fix eeprom firmware load on boards with 16MHz Xtal

For i2c normal work, we need to slow down the bus speed. However, the
slow down breaks the eeprom firmware load. So, use normal speed for
eeprom booting and then restore the i2c speed after that.

It should also be noticed that no other I2C transfer should be in course
while booting from eeprom, otherwise, tda10046 goes into an instable
state. So, proper locking are needed at the i2c bus master.

Tested with saa7134 MSI TV @nyware A/D board, that comes with an eeprom
with firmware version 29.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/tda1004x.c

@@ -162,7 +162,7 @@ static int tda1004x_read_byte(struct tda1004x_state *state, int reg)
 	if (ret != 2) {
 		dprintk("%s: error reg=0x%x, ret=%i\n", __func__, reg,
 			ret);
-		return -1;
+		return -EINVAL;
 	}
 
 	dprintk("%s: success reg=0x%x, data=0x%x, ret=%i\n", __func__,
@@ -481,16 +481,18 @@ static void tda10046_init_plls(struct dvb_frontend* fe)
 static int tda10046_fwupload(struct dvb_frontend* fe)
 {
 	struct tda1004x_state* state = fe->demodulator_priv;
-	int ret;
+	int ret, confc4;
 	const struct firmware *fw;
 
 	/* reset + wake up chip */
 	if (state->config->xtal_freq == TDA10046_XTAL_4M) {
-		tda1004x_write_byteI(state, TDA1004X_CONFC4, 0);
+		confc4 = 0;
 	} else {
 		dprintk("%s: 16MHz Xtal, reducing I2C speed\n", __func__);
-		tda1004x_write_byteI(state, TDA1004X_CONFC4, 0x80);
+		confc4 = 0x80;
 	}
+	tda1004x_write_byteI(state, TDA1004X_CONFC4, confc4);
+
 	tda1004x_write_mask(state, TDA10046H_CONF_TRISTATE1, 1, 0);
 	/* set GPIO 1 and 3 */
 	if (state->config->gpio_config != TDA10046_GPTRI) {
@@ -508,13 +510,29 @@ static int tda10046_fwupload(struct dvb_frontend* fe)
 	if (tda1004x_check_upload_ok(state) == 0)
 		return 0;
 
+	/*
+	   For i2c normal work, we need to slow down the bus speed.
+	   However, the slow down breaks the eeprom firmware load.
+	   So, use normal speed for eeprom booting and then restore the
+	   i2c speed after that. Tested with MSI TV @nyware A/D board,
+	   that comes with firmware version 29 inside their eeprom.
+
+	   It should also be noticed that no other I2C transfer should
+	   be in course while booting from eeprom, otherwise, tda10046
+	   goes into an instable state. So, proper locking are needed
+	   at the i2c bus master.
+	 */
 	printk(KERN_INFO "tda1004x: trying to boot from eeprom\n");
-	tda1004x_write_mask(state, TDA1004X_CONFC4, 4, 4);
+	tda1004x_write_byteI(state, TDA1004X_CONFC4, 4);
 	msleep(300);
-	/* don't re-upload unless necessary */
+	tda1004x_write_byteI(state, TDA1004X_CONFC4, confc4);
+
+	/* Checks if eeprom firmware went without troubles */
 	if (tda1004x_check_upload_ok(state) == 0)
 		return 0;
 
+	/* eeprom firmware didn't work. Load one manually. */
+
 	if (state->config->request_firmware != NULL) {
 		/* request the firmware, this will block until someone uploads it */
 		printk(KERN_INFO "tda1004x: waiting for firmware upload...\n");