V4L/DVB (6546): Add comments for the hint methods
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/em28xx/em28xx-cards.c b/drivers/media/video/em28xx/em28xx-cards.c
index fd7a8a5..e88bf67 100644
--- a/drivers/media/video/em28xx/em28xx-cards.c
+++ b/drivers/media/video/em28xx/em28xx-cards.c
@@ -397,11 +397,13 @@
};
MODULE_DEVICE_TABLE (usb, em28xx_id_table);
-static struct em28xx_hash_table em28xx_hash [] = {
+/* EEPROM hash table for devices with generic USB IDs */
+static struct em28xx_hash_table em28xx_eeprom_hash [] = {
/* P/N: SA 60002070465 Tuner: TVF7533-MF */
{ 0x6ce05a8f, EM2820_BOARD_PROLINK_PLAYTV_USB2, TUNER_YMEC_TVF_5533MF },
};
+/* I2C devicelist hash table for devices with generic USB IDs */
static struct em28xx_hash_table em28xx_i2c_hash[] = {
{ 0xb06a32c3, EM2800_BOARD_TERRATEC_CINERGY_200, TUNER_LG_PAL_NEW_TAPC },
{ 0xf51200e3, EM2800_BOARD_VGEAR_POCKETTV, TUNER_LG_PAL_NEW_TAPC },
@@ -484,10 +486,18 @@
{
int i;
- for (i = 0; i < ARRAY_SIZE(em28xx_hash); i++) {
- if (dev->hash == em28xx_hash[i].hash) {
- dev->model = em28xx_hash[i].model;
- dev->tuner_type = em28xx_hash[i].tuner;
+ /* HINT method: EEPROM
+ *
+ * This method works only for boards with eeprom.
+ * Uses a hash of all eeprom bytes. The hash should be
+ * unique for a vendor/tuner pair.
+ * There are a high chance that tuners for different
+ * video standards produce different hashes.
+ */
+ for (i = 0; i < ARRAY_SIZE(em28xx_eeprom_hash); i++) {
+ if (dev->hash == em28xx_eeprom_hash[i].hash) {
+ dev->model = em28xx_eeprom_hash[i].model;
+ dev->tuner_type = em28xx_eeprom_hash[i].tuner;
em28xx_errdev("Your board has no unique USB ID.\n");
em28xx_errdev("A hint were successfully done, "
@@ -504,6 +514,15 @@
}
}
+ /* HINT method: I2C attached devices
+ *
+ * This method works for all boards.
+ * Uses a hash of i2c scanned devices.
+ * Devices with the same i2c attached chips will
+ * be considered equal.
+ * This method is less precise than the eeprom one.
+ */
+
/* user did not request i2c scanning => do it now */
if (!dev->i2c_hash)
em28xx_do_i2c_scan(dev);