On Mon, Nov 14, 2011 at 09:35:44PM -0500, Tang Yuantian-B29983 wrote: > Hi Jean Delvare, > > Please find my comments in line. > > > -----Original Message----- > > > > Again, no. PMBus goes on top of SMBus which includes SMBus block reads > > (i2c_smbus_read_block_data) but not I2C block reads > > (i2c_smbus_read_i2c_block_data). As a result, many hardware SMBus > > controllers do not support I2C block reads, and it can't be added (only > > the set of transfers supported by the hardware controller can be > > implemented by the driver) which means that your proposed change would > > break support on existing systems. This is not acceptable. > > > > On the other hand, an I2C controller which supports I2C block reads can > > almost always get SMBus block reads added, it's only a matter of adding a > > few lines of code to the bus driver. > > > > Which i2c bus driver are you using? From which kernel version? > > > [Yuantian:] I am using newest kernel 3.2. PowerPC arch. > I2c bus driver file is: drivers/i2c/busses/i2c-mpc.c. > > I greped the i2c bus driver and found the following platform's i2c don't > Support i2c_smbus_read_block_data. So Zl6100 driver can't work on these platforms. > 1. drivers/i2c/busses/i2c-mpc.c(powerpc arch, which I am working on). > 2. drivers/i2c/busses/i2c-mv64xxx.c > 3. drivers/i2c/busses/i2c-nomadik.c > 4. drivers/i2c/busses/i2c-octeon.c > 5. drivers/i2c/busses/i2c-pxa.c > 6. drivers/i2c/busses/i2c-s6000.c > Almost all the platforms the kernel support. > But they all support I2C_FUNC_SMBUS_EMUL, which means support i2c_smbus_read_i2c_block_data. Hmm ... looking into the code, I2C_FUNC_SMBUS_READ_BLOCK_DATA is missing from I2C_FUNC_SMBUS_EMUL. Now that is interesting. If you change mpc_functionality() to return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA; I bet your problem will disappear. Jean, any idea why I2C_FUNC_SMBUS_EMUL doesn't include I2C_FUNC_SMBUS_READ_BLOCK_DATA ? Thanks, Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
