On Fri, 2013-11-29 at 17:32 +0800, Kuo-Jung Su wrote: > > Unfortunately I still cannot agree with you. > > In my opinion I2C driver has nothing to do with current situation. > > > > Yes, that's why I said the root cause is U-Boot's I2C model. > The address should never be rebuilt/reformated inside the I2C driver. > The better solution is to update the i2c_read/i2c_write to: > > int i2c_read(struct i2c_adapter *adap, u8 dev, uint *addr, int alen, > uchar *buf, int len) > > or > > int i2c_read(struct i2c_adapter *adap, u8 dev, uchar *buf, int len) > > i.e., drop the use of uint 'addr'
Well, even in current state of I2C core and some particular drivers (like DW I2C) no reformat of address happens as far as I can tell. But I cannot tell about each and every I2C driver in U-boot. Still if you'd like to modify "U-Boot's I2C model" it is up to you to start this discussion/work if you haven't start it yet (sorry I don't read entire U-boot mailing list daily). But then it's good to modify all drivers as well so nobody gets dead/not-built I2C drivers at some point, right? > > It's purely how manufacturers of EEPROM use I2C. > > For example I we use "PCF8594C-2" EEPROM. > > Here's a datasheet - > > http://www.nxp.com/documents/data_sheet/PCF8594C_2.pdf > > > > Its capacity is 512 bytes. And as you may see from "Fig 3. Device > > addressing." Each IC houses 2 virtual EEPROMs (each housing 256 bytes of > > data). > > > > Yes, it looks like a special case which use BIT0 of device address > for page selection. Which means we can't directly pass the device address > to i2c_read/i2c_write. But it's still o.k to directly the 'offset' as > what we did before. Frankly I don't understand how passing entire "offset" will work in this particular corner-case. From my explanation you see that we have to mimic 8-bit address of target byte in EEPROM. And even if our I2C controller may use 10 bits for addressing it is something that we don't want use here - we need 8-bit as we do now. Regards, Alexey _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
