diff options
Diffstat (limited to 'drivers/i2c/i2c-core-acpi.c')
-rw-r--r-- | drivers/i2c/i2c-core-acpi.c | 38 |
1 files changed, 36 insertions, 2 deletions
diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c index d84095591e45..ac5150ee0803 100644 --- a/drivers/i2c/i2c-core-acpi.c +++ b/drivers/i2c/i2c-core-acpi.c @@ -39,6 +39,7 @@ struct i2c_acpi_lookup { int index; u32 speed; u32 min_speed; + u32 force_speed; }; /** @@ -259,6 +260,19 @@ i2c_acpi_match_device(const struct acpi_device_id *matches, return acpi_match_device(matches, &client->dev); } +static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = { + /* + * These Silead touchscreen controllers only work at 400KHz, for + * some reason they do not work at 100KHz. On some devices the ACPI + * tables list another device at their bus as only being capable + * of 100KHz, testing has shown that these other devices work fine + * at 400KHz (as can be expected of any recent i2c hw) so we force + * the speed of the bus to 400 KHz if a Silead device is present. + */ + { "MSSL1680", 0 }, + {} +}; + static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level, void *data, void **return_value) { @@ -277,6 +291,9 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level, if (lookup->speed <= lookup->min_speed) lookup->min_speed = lookup->speed; + if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0) + lookup->force_speed = 400000; + return AE_OK; } @@ -314,7 +331,16 @@ u32 i2c_acpi_find_bus_speed(struct device *dev) return 0; } - return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0; + if (lookup.force_speed) { + if (lookup.force_speed != lookup.min_speed) + dev_warn(dev, FW_BUG "DSDT uses known not-working I2C bus speed %d, forcing it to %d\n", + lookup.min_speed, lookup.force_speed); + return lookup.force_speed; + } else if (lookup.min_speed != UINT_MAX) { + return lookup.min_speed; + } else { + return 0; + } } EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed); @@ -345,10 +371,18 @@ static struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle) static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev) { struct device *dev; + struct i2c_client *client; dev = bus_find_device(&i2c_bus_type, NULL, adev, i2c_acpi_find_match_device); - return dev ? i2c_verify_client(dev) : NULL; + if (!dev) + return NULL; + + client = i2c_verify_client(dev); + if (!client) + put_device(dev); + + return client; } static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value, |