diff options
| -rw-r--r-- | drivers/media/usb/em28xx/em28xx-cards.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c index 5e127e48c945..930e3e3fc948 100644 --- a/drivers/media/usb/em28xx/em28xx-cards.c +++ b/drivers/media/usb/em28xx/em28xx-cards.c @@ -37,6 +37,7 @@ #include <media/i2c-addr.h> #include <media/tveeprom.h> #include <media/v4l2-common.h> +#include <sound/ac97_codec.h> #include "em28xx.h" @@ -2563,6 +2564,36 @@ static inline void em28xx_set_model(struct em28xx *dev) dev->def_i2c_bus = dev->board.def_i2c_bus; } +/* Wait until AC97_RESET reports the expected value reliably before proceeding. + * We also check that two unrelated registers accesses don't return the same + * value to avoid premature return. + * This procedure helps ensuring AC97 register accesses are reliable. + */ +static int em28xx_wait_until_ac97_features_equals(struct em28xx *dev, + int expected_feat) +{ + unsigned long timeout = jiffies + msecs_to_jiffies(2000); + int feat, powerdown; + + while (time_is_after_jiffies(timeout)) { + feat = em28xx_read_ac97(dev, AC97_RESET); + if (feat < 0) + return feat; + + powerdown = em28xx_read_ac97(dev, AC97_POWERDOWN); + if (powerdown < 0) + return powerdown; + + if (feat == expected_feat && feat != powerdown) + return 0; + + msleep(50); + } + + em28xx_warn("AC97 registers access is not reliable !\n"); + return -ETIMEDOUT; +} + /* Since em28xx_pre_card_setup() requires a proper dev->model, * this won't work for boards with generic PCI IDs */ @@ -2668,6 +2699,13 @@ static void em28xx_pre_card_setup(struct em28xx *dev) em28xx_write_reg(dev, EM2820_R08_GPIO_CTRL, 0xfd); msleep(70); break; + + case EM2860_BOARD_TERRATEC_GRABBY: + /* HACK?: Ensure AC97 register reading is reliable before + * proceeding. In practice, this will wait about 1.6 seconds. + */ + em28xx_wait_until_ac97_features_equals(dev, 0x6a90); + break; } em28xx_gpio_set(dev, dev->board.tuner_gpio); |