Hi Stephen, On Thu, Jan 12, 2012 at 11:21 AM, Stephen Warren <swar...@nvidia.com> wrote: > Simon Glass wrote at Thursday, January 12, 2012 12:10 PM: >> On Thu, Jan 12, 2012 at 10:59 AM, Stephen Warren <swar...@nvidia.com> wrote: >> > Simon Glass wrote at Wednesday, January 11, 2012 8:00 PM: > ... >> >> Also U-Boot tends to call i2c_init() before every use of i2c, whereas >> >> we just want to init once and be done with it. >> >> >> >> I think the function name is correct, but perhaps I should change the >> >> #ifdef you mention in 1 above to CONFIG_SYS_I2C_INIT_BOARD. But for >> >> i2c to function on Tegra boards, this must be defined, so in fact this >> >> might be counterproductive. So perhaps a check that it is defined is >> >> best? >> > >> > But README explicitly says that i2c_init_board() is for bus unhanging >> > which isn't what the Tegra implementation does. How can the function >> > name be correct given that? >> >> Well we should rename the function IMO. It seems to me that with a a >> name like that it is for initing i2c on the board. > > You mean change the function that's activated by CONFIG_SYS_I2C_INIT_BOARD > to be something more like i2c_unhang_board()? That makes sense to me. I > have no idea how much of a hassle it'd be to update any existing boards.
Well we should change the README or change the function name. I'm not sure which is correct. > >> > Don't we just want to make i2c_init() use a global/static variable to >> > determine whether the device has already been initialized, and defer all >> > the init until first usage or something like that? That seems in line >> > with U-Boot's desire not to initialize drivers until they're actually >> > used. >> >> Actually that might work - if we keep i2c_init() a no-op, and wait >> until we get a request for a bus before we look up the fdt and init >> that port. But I suspect we might need to init port 0 immediately >> since there is no explicit call to i2c_set_bus_num() for that. It's a >> little wonky whatever we do. What do you think? > > It does make sense to me to at least parse out all the DT stuff early > on, so there's a single place to do all the alias processing etc. Given > what I just wrote in the other email about fixing the I2C bus speed > stuff, would making those changes here help this at all? I think the device tree processing should be done later because i2c_init() is called very early, before the dcache is enabled. It is very s l o w to touch device tree before then. To be honest, that's another reason for leaving it as it is, with i2c_init() being a no-op. But we might be able to init the bus on first use with enough if() statements :-) I will take a look. I am not going to refactor U-Boot I2C here, although I think it could use a few tweaked... Regards, Simon > > -- > nvpublic > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
