> Hello, > > I have MPC880 microprocessor based board with single 24C02 I2C EEPROM, > connected to the I2C bus. > Per suggestion from Tom Rini I copied i2c-algo-8xx.h from Linux 2.4.26 into 2.6.10-rc3 code source and made couple small changes to allow building of the 8xx code with I2C configured, please see: http://archives.andrew.net.au/lm-sensors/msg28725.html > > 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 > >
