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authorMoiz Sonasath <m-sonasath@ti.com>2010-02-16 18:57:21 -0600
committerSamuel Ortiz <sameo@linux.intel.com>2010-03-07 22:17:23 +0100
commita29aaf55cd6faa75e35abfe00bd3ffc537490485 (patch)
tree8f883a25bb154df5bff43a3980752a973da99a10 /drivers/mfd
parente82c60ae7d3a7f19c4b9b3e7bd6ea298fa5efe93 (diff)
downloadlinux-a29aaf55cd6faa75e35abfe00bd3ffc537490485.tar.bz2
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/mfd')
-rw-r--r--drivers/mfd/twl-core.c13
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)