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Commit a29aaf55 authored by Moiz Sonasath's avatar Moiz Sonasath Committed by Samuel Ortiz
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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: default avatarMoiz Sonasath <m-sonasath@ti.com>
Signed-off-by: default avatarAllen Pais <allen.pais@ti.com>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent e82c60ae

drivers/mfd/twl-core.c

+13 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/i2c/twl.h

+15 −0
Original line number Diff line number Diff line
@@ -239,6 +239,21 @@ int twl6030_interrupt_mask(u8 bit_mask, u8 offset); 


/*----------------------------------------------------------------------*/



/*Interface Bit Register (INTBR) offsets

 *(Use TWL_4030_MODULE_INTBR)

 */



#define REG_GPPUPDCTR1			0x0F



/*I2C1 and I2C4(SR) SDA/SCL pull-up control bits */



#define I2C_SCL_CTRL_PU			BIT(0)

#define I2C_SDA_CTRL_PU			BIT(2)

#define SR_I2C_SCL_CTRL_PU		BIT(4)

#define SR_I2C_SDA_CTRL_PU		BIT(6)



/*----------------------------------------------------------------------*/



/*

 * Keypad register offsets (use TWL4030_MODULE_KEYPAD)

 * ... SIH/interrupt only