[media] lirc_zilog: z8 on usb doesn't like back-to-back i2c_master_send

Both the HD-PVR and HVR-1950, driven by the hdpvr and pvrusb2 drivers
respectively, have a zilog z8 chip exposed via i2c. These are both
usb-connected devices, and on both of them, back-to-back i2c_master_send
calls that work fine with a z8 on a pci card fail with a -EIO, as the
chip isn't yet ready from the prior command. To cope with that, add a
delay and retry loop where necessary.

Acked-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/lirc/lirc_zilog.c

@@ -495,23 +495,35 @@ static int send_data_block(struct IR_tx *tx, unsigned char *data_block)
 /* send boot data to the IR TX device */
 static int send_boot_data(struct IR_tx *tx)
 {
-	int ret;
+	int ret, i;
 	unsigned char buf[4];
 
 	/* send the boot block */
 	ret = send_data_block(tx, tx_data->boot_data);
 	if (ret != 0)
 		return ret;
 
-	/* kick it off? */
+	/* Hit the go button to activate the new boot data */
 	buf[0] = 0x00;
 	buf[1] = 0x20;
 	ret = i2c_master_send(tx->c, buf, 2);
 	if (ret != 2) {
 		zilog_error("i2c_master_send failed with %d\n", ret);
 		return ret < 0 ? ret : -EFAULT;
 	}
-	ret = i2c_master_send(tx->c, buf, 1);
+
+	/*
+	 * Wait for zilog to settle after hitting go post boot block upload.
+	 * Without this delay, the HD-PVR and HVR-1950 both return an -EIO
+	 * upon attempting to get firmware revision, and tx probe thus fails.
+	 */
+	for (i = 0; i < 10; i++) {
+		ret = i2c_master_send(tx->c, buf, 1);
+		if (ret == 1)
+			break;
+		udelay(100);
+	}
+
 	if (ret != 1) {
 		zilog_error("i2c_master_send failed with %d\n", ret);
 		return ret < 0 ? ret : -EFAULT;
@@ -523,8 +535,8 @@ static int send_boot_data(struct IR_tx *tx)
 		zilog_error("i2c_master_recv failed with %d\n", ret);
 		return 0;
 	}
-	if (buf[0] != 0x80) {
-		zilog_error("unexpected IR TX response: %02x\n", buf[0]);
+	if ((buf[0] != 0x80) && (buf[0] != 0xa0)) {
+		zilog_error("unexpected IR TX init response: %02x\n", buf[0]);
 		return 0;
 	}
 	zilog_notify("Zilog/Hauppauge IR blaster firmware version "
@@ -827,7 +839,15 @@ static int send_code(struct IR_tx *tx, unsigned int code, unsigned int key)
 		zilog_error("i2c_master_send failed with %d\n", ret);
 		return ret < 0 ? ret : -EFAULT;
 	}
-	ret = i2c_master_send(tx->c, buf, 1);
+
+	/* Give the z8 a moment to process data block */
+	for (i = 0; i < 10; i++) {
+		ret = i2c_master_send(tx->c, buf, 1);
+		if (ret == 1)
+			break;
+		udelay(100);
+	}
+
 	if (ret != 1) {
 		zilog_error("i2c_master_send failed with %d\n", ret);
 		return ret < 0 ? ret : -EFAULT;