Hello ksi, k...@koi8.net wrote: > On Mon, 16 Feb 2009, Wolfgang Denk wrote: > > >> Dear k...@koi8.net, >> >> In message <pine.lnx.4.64ksi.0902142104100.6...@home-gw.koi8.net> you wrote: >> >>> OK, please explain how that cur_adap_nr->hwadapnr gets assigned. Please also >>> explain how can one invoke a function on other adapter than "current". >>> Remember, i2c_init is quite often called BEFORE the code is relocated to RAM >>> so you can NOT change "current" adapter. >>> >> We could assign an entry in the global data for it. >> >> But then - how often will it bbe necessary to switch adapters before >> relocation? What is I2C being used for? To read the SPD data for the >> RAM init code. Which other adapter would be needed? >> > > I can not tell it right away. There might be several RAM DIMMs with their > own SPD EPROMS sitting on different busses or something else. It is not like > we absolutely need this feature right now, urgently but it is so easy to > implement that it would've been a crime to not to... :) > > There is another problem with choosing a proper i2c_init() function with > i2c_set_bus_num() -- the latter also reprograms I2C multiplexers/switches if > there are any so you essentially need an initialized adapter to switch to it > to initialize it. Catch 22... >
That would not be a problem: if we are running from flash we could always init in i2c_set_bus_num() first the new controllor to which we switch. And if we are running in ram we can always check in i2c_set_bus_num() if adap->init_done in i2c_adap_t is 1. If this is not so, we first init the bus! With this, it should be possible to get rid of all this i2c_init calls all over the code ... One requirement for this: All "old" code who directly call i2c_read, i2c_write, ... must, if this new feature is activated, call a i2c_set_bus_num() before accessing the bus. But this would be only "work" (grep and fix). bye Heiko -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
