Hello ksi,
ksi@koi8.net wrote:
On Wed, 18 Feb 2009, Heiko Schocher wrote:
Heiko Schocher schrieb:
ksi@koi8.net wrote:
On Mon, 16 Feb 2009, Wolfgang Denk wrote:
Dear ksi@koi8.net,
In message Pine.LNX.4.64ksi.0902142019520.6240@home-gw.koi8.net you wrote:
[...]
And remember, the devil is in details. How are you going to assign (initialize) that innocent looking "cur_adap_nr->hwadapnr"? How are you going to work on an adapter other that "current" in a situation when you can NOT change "current" adapter (e.g. perform all I2C layer initialization while still running from flash?) Remember, this is plain C and there is no
What makes you insist that we cannot change a variable if we need to be able to change one?
It is NOT just variable. My approach uses i2c _BUS_, not _ADAPTER_. And number of busses can be bigger than number of adapters (e.g. when some busses a reached via muxes or switches.) When doing i2c_set_current_bus() you are switching _NOT_ adapters, but busses. That involves not only changing that global variable but also reprogramming muxes/switches for i2c_set_current_bus() to be consistent and hardware independent. Otherwise
You have no i2c_set_current_bus() in your code! I think you mean i2c_set_current_bus(), right?
And this function fails when running from flash! So, how can you switch busses with your patches when running from flash?
PLease answer my question!!!
How can you switch busses when running from flash???
Here your function:
int i2c_set_bus_num(unsigned int bus) { #ifndef CONFIG_SYS_I2C_DIRECT_BUS int i; u_int8_t buf; #endif
if ((bus >= CONFIG_SYS_NUM_I2C_BUSSES) || !(gd->flags & GD_FLG_RELOC)) return(-1);[...]
This function wouldn;t work from flash ...
And one more reason, why your function will not work from flash:
later in your i2c_set_bus_num function: [...] if ((i2c_bus[i2c_cur_bus].next_hop[0].chip != 0) && (ADAP(i2c_cur_bus)->init_done != 0)) {
You only switch muxes if init_done != 0 ... but init_done is not writeable when running from flash, so it is "= 0" when code is not relocated ... how work this for you?
Again, how work this!
But this can be solved, if we always init the hardwareadapter when switching to it and running from flash ... and if we are relocated, we can analyse this flag, if init_done = 0, we init this hardware adapter ...
My proposal for the i2c_set_bus_num(unsigned int bus) function:
int i2c_set_bus_num(unsigned int bus) { #ifndef CONFIG_SYS_I2C_DIRECT_BUS int i; u_int8_t buf; #endif
if (bus >= CONFIG_SYS_NUM_I2C_BUSSES) return(-1);
#ifndef CONFIG_SYS_I2C_DIRECT_BUS /* Disconnect current bus (turn off muxes if any) */ if ((i2c_bus[i2c_cur_bus].next_hop[0].chip != 0) && (ADAP(i2c_cur_bus)->init_done != 0)) {
i = CONFIG_SYS_I2C_MAX_HOPS; do { u_int8_t chip; if ((chip = i2c_bus[i2c_cur_bus].next_hop[--i].chip) == 0) continue; ADAP(i2c_cur_bus)->write(chip, 0, 0, &buf, 1); } while (i > 0);} #endif
cur_adap_nr = (i2c_adap_t *)&ADAP(bus); if (ADAP(bus)->init_done == 0) { i2c_init_bus(bus, ADAP(bus)->speed, ADAP(bus)->slaveaddr); }
#ifndef CONFIG_SYS_I2C_DIRECT_BUS /* Connect requested bus if behind muxes */ if (i2c_bus[bus].next_hop[0].chip != 0) {
/* Set all muxes along the path to that bus */ for (i = 0; i < CONFIG_SYS_I2C_MAX_HOPS; i++) { if (i2c_bus[bus].next_hop[i].chip == 0) break; i2c_mux_set(i2c_bus[bus].adapter, i2c_bus[bus].next_hop[i].mux.id, i2c_bus[bus].next_hop[i].chip, i2c_bus[bus].next_hop[i].channel); }} #endif
i2c_cur_bus = bus; return(0); }
This function should also work, when running from flash. + a hardware adapter is only initialized when we switch to it, so no need to initialize all hardwareadapters somewhere ... (requirement: cur_adap_nr, i2c_cur_bus is writeable when running in flash)
You are multiplying entities. i2c_init() is invoked as a part of system
But Wolfgang suggested to init an I2C adapter just if we use it, and above function will do this. Again read my EMails. I wrote:
This function should also work, when running from flash. + a hardware adapter is only initialized when we switch to it, so no need to initialize all hardwareadapters somewhere ...
So no need for calling i2c_init in libXXX/board.c or somewhere. We must just look that for example in dtt_init is also a i2c_set_bus_num () called.
bootup process in libXXX/board.c anyways. There is no need for any global variables, even non-writable for proposed code to initialize adapters.
Not for initialize adapters, because you want to init all adapters. But if we want to do what Wolfgang suggested, we don;t need to call i2c_init for all adapters.
bye Heiko