mfd: Disable TWL4030/5030 I2C1/I2C4 internal pull-ups
authorMoiz Sonasath <m-sonasath@ti.com>
Wed, 17 Feb 2010 00:57:21 +0000 (18:57 -0600)
committerSamuel Ortiz <sameo@linux.intel.com>
Sun, 7 Mar 2010 21:17:23 +0000 (22:17 +0100)
commita29aaf55cd6faa75e35abfe00bd3ffc537490485
tree8f883a25bb154df5bff43a3980752a973da99a10
parente82c60ae7d3a7f19c4b9b3e7bd6ea298fa5efe93
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>
drivers/mfd/twl-core.c
include/linux/i2c/twl.h