i2c: imx: could not read data

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

Hello,

On Sat, Jul 28, 2012 at 10:07:35PM +0200, Gabriel Tisan wrote:
> I have the following environment :
> - Kernel based on 3.2.21 with custom changes and with commit (bb79a07)
> "i2c: imx: fix imx driver to work though signal is pending" applied
> - board based on imx35 derived from Freescale i.MX35 3-stack eval board
> 
> I try to read some data from I2C by following userspace application,
> but I get some error:
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <errno.h>
> 
> #include <linux/i2c-dev.h>
> 
> int main() {
> 	int file, i;
> 	char filename[20];
> 	char buf[3];
> 	int adapter_nr = 0; /* I2C-0 */
> 	int addr = 0x08; /* The I2C address */	
>   	char reg = 0x07; /* Device register to access */
> 
> 	snprintf(filename, 19, "/dev/i2c-%d", adapter_nr);
> 	file = open(filename, O_RDWR);
> 	if (file < 0) {
> 		printf("%s: open failed: %s\n",file, strerror(errno));
> 		exit(1);
> 	}
> 
> 	if (ioctl(file, I2C_SLAVE, addr) < 0) {
> 		printf("%s: set slave address failed: %s\n",file, strerror(errno));
> 		exit(1);
> 	}
> 
> 	buf[0] = reg;
> 	buf[1] = 0;
> 	buf[2] = 0;
> 	if (write(file, buf, 1) != 1) {
> 		printf("%s: write failed: %s\n",file, strerror(errno));
> 		exit(1);
> 	}
> 
> 	if (read(file, buf, 2) != 2) {
> 		printf("%s: read failed: %s\n",filename, strerror(errno));
> 		exit(1);
> 	} else {
> 	    printf("Read bytes\n");
> 		/* buf contains the ID bytes */
> 		printf("ID: ");
> 	 	for (i=0; i<2; i++) {
> 			printf("%02x ",buf[i]);
> 		}
> 	}	
> 	return 0;
> }
> 
> Here is the debug log with the error that I get when i run the program
> from above:
> i2c i2c-0: ioctl, cmd=0x703, arg=0x08
> i2c-dev: i2c-0 writing 1 bytes.
> i2c i2c-0: master_xfer[0] W, addr=0x08, len=1
> i2c i2c-0: <i2c_imx_xfer>
> i2c i2c-0: <i2c_imx_start>
> i2c i2c-0: <i2c_imx_bus_busy>
> i2c i2c-0: <i2c_imx_xfer> transfer message: 0
> i2c i2c-0: <i2c_imx_xfer> CONTROL: IEN=1, IIEN=1, MSTA=1, MTX=1, TXAK=1, RSTA=0
> i2c i2c-0: <i2c_imx_xfer> STATUS: ICF=1, IAAS=0, IBB=1, IAL=0, SRW=0,
> IIF=0, RXAK=1
> i2c i2c-0: <i2c_imx_write> write slave address: addr=0x10
> i2c i2c-0: <i2c_imx_trx_complete> TRX complete
> i2c i2c-0: <i2c_imx_acked> ACK received
> i2c i2c-0: <i2c_imx_write> write data
> i2c i2c-0: <i2c_imx_write> write byte: B0=0x7
> i2c i2c-0: <i2c_imx_trx_complete> TRX complete
> i2c i2c-0: <i2c_imx_acked> ACK received
> i2c i2c-0: <i2c_imx_stop>
> i2c i2c-0: <i2c_imx_bus_busy>
> i2c i2c-0: <i2c_imx_xfer> exit with: success msg: 1
> i2c-dev: i2c-0 reading 2 bytes.
> i2c i2c-0: master_xfer[0] R, addr=0x08, len=2
> i2c i2c-0: <i2c_imx_xfer>
> i2c i2c-0: <i2c_imx_start>
> i2c i2c-0: <i2c_imx_bus_busy>
> i2c i2c-0: <i2c_imx_xfer> transfer message: 0
> i2c i2c-0: <i2c_imx_xfer> CONTROL: IEN=1, IIEN=1, MSTA=1, MTX=1, TXAK=1, RSTA=0
> i2c i2c-0: <i2c_imx_xfer> STATUS: ICF=1, IAAS=0, IBB=1, IAL=0, SRW=0,
> IIF=0, RXAK=1
> i2c i2c-0: <i2c_imx_read> write slave address: addr=0x11
> i2c i2c-0: <i2c_imx_trx_complete> TRX complete
> i2c i2c-0: <i2c_imx_acked> No ACK
> i2c i2c-0: <i2c_imx_stop>
> i2c i2c-0: <i2c_imx_bus_busy>
> i2c i2c-0: <i2c_imx_xfer> exit with: error: -5
> 
> Using i2ctools it seems that with i2c everything is fine:
> # i2cdetect -l
> i2c-0i2c       imx-i2c                         I2C adapter
> i2c-1i2c       imx-i2c                         I2C adapter
> i2c-2i2c       imx-i2c                         I2C adapter
> # i2cdetect -y 0
>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
> 00:          -- -- -- -- -- 08 -- -- -- -- -- -- --
> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 70: -- -- -- -- -- -- -- --
> # i2cget -y 0 0x08 07 w
> 0x4100
> 
> How you can see using i2ctools I can read without any errors from
> register 07 of slave device 08 found on i2c-0.
> On the same board using an old kernel 2.6.32.16 I can read data from
> i2c-0 using my userspace app.
> 
> Has anybody some suggestions what could I try to go forward ?
As your problem seems to be more i2c related than arm related I suggest
asking your question on the i2c list.

Other than that I'd take a look into the source of i2cget.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |