am335x tsc2007.c bug

user4135049

Other Parts Discussed in Thread: TSC2007

i use /drivers/input/touchscreen/tsc2007.c with am335x, but it looks like this. i do not know why it happens.

static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)

{

..........

data = i2c_smbus_read_word_data(tsc->client, cmd);/*here is the bug.*/

............

}

as we know, the data will be sent after the ack after slave address, but here we received the ack but then data disappeared!!!!!

0 Biser Gatchev-XID over 10 years ago

From what you have written there is no information what your problem is. Please provide a more detailed description of the problem.

0 user4135049 over 10 years ago in reply to Biser Gatchev-XID

thank you.

0 Biser Gatchev-XID over 10 years ago in reply to user4135049

Take a look at this post and below - there is a working solution posted there: http://e2e.ti.com/support/arm/sitara_arm/f/791/p/368154/1298853.aspx#1298853

0 user4135049 over 10 years ago in reply to Biser Gatchev-XID

it looks like he just add the support for device tree. but the problem code is same. so does sdk6.0 linux has bugs on smbus?

0 Wolfgang Muees1 over 10 years ago

Genius 3685 points

You have a spike on the SDA line, at the time of the ACK from the touch screen.

- Add a resistor of 100 Ohm in the SDA line, at the touchscreen controller.

- Or: add a small capacitor from the SDA line to GND. Try 100pF.

- You may also add a small capacitor from SCL to GND, if SDA and SCL are routed in parallel.

regards

Wolfgang

0 user4135049 over 10 years ago in reply to Wolfgang Muees1

i find no matter i use i2c_smbus_write_byte_data(); or i2c_master_send(); the driver code goes here,

{
........
return -EREMOTEIO;
/*
* this line is in

* static int omap_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
* which is in /drivers/i2c/busses/i2c-omap.c

*/
........
}
i don't know what makes it..

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