El Tue, Aug 04, 2009 at 09:42:41PM +0300 NiTr0 ha dit: > I tried to improve voltage/FSB manipulation module for EeePC > (http://code.google.com/p/eeepc-linux) - and I found that > i2c_smbus_write_block_data will cause kernel panic when is called from > function called by timer. I can't see kernel panic message because > system print very long call trace. Also on EeePC there is no RS232 port > - but I have USB->RS232 dongle, can it be used as terminal for debug > messages? > > All variables are declared as static, all data is prepared correctly - > so IMHO trouble is outside of my driver. > There is a part of code: > > static struct i2c_client eee_pll_smbus_client = { > .adapter = NULL, > .addr = 0x69, > .flags = 0, > }; > static char eee_pll_data[I2C_SMBUS_BLOCK_MAX]; > static int eee_pll_datalen = 0; > ....................... > i2c_smbus_write_block_data(&eee_pll_smbus_client,0, > eee_pll_datalen, eee_pll_data); a possible source of problems is that i2c_smbus_xfer() (invoked by i2c_smbus_write_block_data()) tries to aquire a mutex if adapter->algo->smbus_xfer is set. http://lxr.linux.no/linux+v2.6.30/drivers/i2c/i2c-core.c#L1994 timers are executed in a softirq, ie in interrupt context, but mutexes must not be used within interrupts. i'm neither an i2c-core nor an kernel expert, but this point looks conflictive to me and might be the reason for the kernel panic you get. -- Matthias Kaehlcke Embedded Linux Engineer Barcelona They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety (Benjamin Franklin) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
