Hello,
>
> I have MPC880 microprocessor based board with single 24C02 I2C EEPROM,
> connected to the I2C bus.
>
> Currently booting of the board hangs in the I2C driver after invocation of
> interruptible_sleep_on( )
function call in cpm_iic_tryaddress( ) function (in i2c-algo-8xx.c file).
Is it appropriate to use the interruptible_sleep_on( ) function at the
kernel booting stage ?
(I personally do not think so - since such usage prevents further kernel
booting - as observed).
What should be done in this code to avoid slleping ?
I presume that the usage of the interruptible_sleep_on( ) function would be
appropriate if the
I2C would be configured as a module (after the kernel booting is completed)
?
Follow up question: is it really expected to do I2C initialization ONLY as
a module after the kernel booting ?
(is it documented anyplace ?)
> The (end of) log buffer shows following:
> ....
> <6>i2c /dev entries driver.
> <7>device class 'i2c-dev': registering.
> <7>bus i2c:add driver dev_driver.
> <7>i2c-core: driver dev_driver registered
> <6>i2c-rpx: i2c MPC8xx driver.
> <7>DEV: registering device: ID ='i2c-0'.
> <7>CLASS: registering class device: ID= 'i2c-0'.
> <7>i2c_adapter i2c-0:Registered as minor 0.
> <7>CLASS:registering class device: ID = 'i2c-0'
> <7>i2c_adapter i2c-0: registered as adapter #0.
> <4>cpm_iic_init() - iip=fa203c80.
> <4>cpm_iic_init[132] Install ISR for IRQ 16.
> <6>CPM interrupt c0105d90 replacing c01f7a8c.
> <3>request_irq() returned -22 for CPM vector 32.
> <6> i2c-algo-8xx.o: scanning bus m8xx........
> <4>cpm_iic_tryaddress(cpm=c019b9f8,addr=0).
> <4>iip fa203c80, dp_addr 0x800.
> <4>iic_tbase 2048, r_tbase 2048
> <4>about to sleep
> .ABOVE LINE IS THE LAST ENTRY IN THE LOG BUFFER - THE BOOT HANGS
> THEREAFTER ...
>
Here is the fragment of the cpm_iic_tryaddress( ) function in
i2c-algo-8xx.c,
where the problem takes place:
....
// save_flags(flags); cli();
i2c->i2c_i2cer = 0xff;
i2c->i2c_i2cmr = 0x13; /* Enable some interupts */
i2c->i2c_i2mod = 1; /* Enable */
i2c->i2c_i2com = 0x81; /* Start master */
// restore_flags(flags);
if (cpm_debug > 1) printk("about to sleep\n");
/* wait for IIC transfer */
interruptible_sleep_on(&iic_wait);
if (signal_pending(current))
return -EIO;
if (cpm_debug > 1) printk("back from sleep\n");
if (tbdf->cbd_sc & BD_SC_NAK) {
if (cpm_debug > 1) printk("IIC try; no ack\n");
return 0;
}
if (tbdf->cbd_sc & BD_SC_READY) {
printk("IIC try; complete but tbuf ready\n");
}
return 1;
........
> Thanks,
> Best Regards,
> Alex
>
>
