On 03/19/2012 07:31 PM, Simon Glass wrote: > Hi Stephen, > > On Mon, Mar 19, 2012 at 6:22 PM, Stephen Warren <swar...@wwwdotorg.org> wrote: >> On 03/19/2012 04:59 PM, Simon Glass wrote: >>> Hi Stephen, >>> >>> On Mon, Mar 19, 2012 at 2:18 PM, Stephen Warren <swar...@wwwdotorg.org> >>> wrote: >>>> On 03/19/2012 02:27 PM, Simon Glass wrote: >>>>> We enable this feature on all UARTs for Seaboard. This ensures that a >>>>> message is printed if CONFIG_OF_CONTROL is in use and a value device tree >>>>> is not available. >>>> >>>> Why not just enabled this on UARTD, since that's what Seaboard uses? >>>> >>>> I guess some derivatives do use UARTB too, which makes things quite >>>> painful. Perhaps at least limit this to UARTB + UARTD, and not all the >>>> others? >>> >>> At the moment we can use Seaboard as a generic Tegra2 board, so we >>> want the widest possible select of UARTs. I think there is one board >>> that uses A? >>> >>> Really I would prefer that we explicitly create a generic Tegra2 >>> board, once the fdt stuff is bedded in. >> >> Well, one of Wolfgang's main objections was blasting the panic message >> through all possible UARTs, which might send junk to something other >> than a debug UART (e.g. machinery and life support systems were >> mentioned). This change doesn't seem to solve that. For low-level debug >> like this, shouldn't we just route it to one single UART that the config >> file selects? > > The objection was that we did it blindly without knowing what ports > were safe to use. Now it is under board control. In the case of a > board where we want the pre-console panic function but only want it on > UARTB we can do that by creating a board file and a config. > > The CONFIG cannot select which UART to use, because we only have one > config for all the Seaboard variants, and some use different UARTs. > Only the device tree can tell you which is the console UART. There is > a bit of a conflict here, but keep in mind we are trying to have a > single U-Boot binary - anything that relies on a CONFIG will break > that.
I don't believe there's any specific requirement or decision to have a single U-Boot binary. Who has decided that and where is the discussion? Having a single set of sources seems like quite a large step for a bootloader, and perhaps can be achieved with DT. Building a binary for each specific debug UART you need (and potentially for many other things) seems entirely reasonable. >> We can certainly think about refactoring things into a unified board >> file, but that seems like something unrelated to do later... > > Yes it is. But we use Seaboard as our base board for all the Tegra2 > board variants. Some use UARTA, C and one uses D. UART D is a pain > because it is shared with SPI. > > So my preference is to leave it as it is, but if you just want it to > be D, then we can go with that for now. At least now it is only a > single line change. Let me know. That seems safest for now, especially considering that only baseline Seaboard is actually supported in mainline U-Boot. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot