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| author | Moiz Sonasath <m-sonasath@ti.com> | 2010-02-16 18:57:21 -0600 |
|---|---|---|
| committer | Samuel Ortiz <sameo@linux.intel.com> | 2010-03-07 22:17:23 +0100 |
| commit | a29aaf55cd6faa75e35abfe00bd3ffc537490485 (patch) | |
| tree | 8f883a25bb154df5bff43a3980752a973da99a10 /drivers | |
| parent | e82c60ae7d3a7f19c4b9b3e7bd6ea298fa5efe93 (diff) | |
| download | linux-a29aaf55cd6faa75e35abfe00bd3ffc537490485.tar.gz linux-a29aaf55cd6faa75e35abfe00bd3ffc537490485.tar.bz2 linux-a29aaf55cd6faa75e35abfe00bd3ffc537490485.zip | |
mfd: Disable TWL4030/5030 I2C1/I2C4 internal pull-ups
This patch disables TWL4030/5030 I2C1 adn I2C4(SR) internal pull-up, to
use only the external HW resistor >=470 Ohm for the assured
functionality in HS mode.
While testing the I2C in High Speed mode, it was discovered that
without a proper pull-up resistor, there is data corruption during
multi-byte transfer. RTC(time_set) test case was used for testing.
From the analysis done, it was concluded that ideally we need a
pull-up of 1.6k Ohm(recomended) or atleast 470 Ohm or greater for
assured performance in HS mode.
Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Allen Pais <allen.pais@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mfd/twl-core.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c index 942a1e837819..7ccc39f3aa48 100644 --- a/drivers/mfd/twl-core.c +++ b/drivers/mfd/twl-core.c @@ -958,6 +958,7 @@ twl_probe(struct i2c_client *client, const struct i2c_device_id *id) int status; unsigned i; struct twl4030_platform_data *pdata = client->dev.platform_data; + u8 temp; if (!pdata) { dev_dbg(&client->dev, "no platform data?\n"); @@ -1025,6 +1026,18 @@ twl_probe(struct i2c_client *client, const struct i2c_device_id *id) goto fail; } + /* Disable TWL4030/TWL5030 I2C Pull-up on I2C1 and I2C4(SR) interface. + * Program I2C_SCL_CTRL_PU(bit 0)=0, I2C_SDA_CTRL_PU (bit 2)=0, + * SR_I2C_SCL_CTRL_PU(bit 4)=0 and SR_I2C_SDA_CTRL_PU(bit 6)=0. + */ + + if (twl_class_is_4030()) { + twl_i2c_read_u8(TWL4030_MODULE_INTBR, &temp, REG_GPPUPDCTR1); + temp &= ~(SR_I2C_SDA_CTRL_PU | SR_I2C_SCL_CTRL_PU | \ + I2C_SDA_CTRL_PU | I2C_SCL_CTRL_PU); + twl_i2c_write_u8(TWL4030_MODULE_INTBR, temp, REG_GPPUPDCTR1); + } + status = add_children(pdata, id->driver_data); fail: if (status < 0) |