Hi Graeme, On Tue, Mar 20, 2012 at 5:17 PM, Graeme Russ <graeme.r...@gmail.com> wrote: > Hi Simon, > > On Wed, Mar 21, 2012 at 11:02 AM, Simon Glass <s...@chromium.org> wrote: >> Hi Graeme, >> >> On Tue, Mar 20, 2012 at 4:52 PM, Graeme Russ <graeme.r...@gmail.com> wrote: >>> Hi Simon, >>> >>> On Wed, Mar 21, 2012 at 10:33 AM, Simon Glass <s...@chromium.org> wrote: > >>>> We cannot select the UART via CONFIG - remember that all of these >>>> boards have the same U-Boot binary. Please read that again :-) The >>>> device tree is the only thing that distinguishes them. All of the >>>> CONFIG options are identical for all boards. >>> >>> But I don't get it - In your Seaboard patch, you only use UARTD so in this >>> case we could CONFIG_ it? >> >> Yes, Stephen specifically asked for this so I changed it. See the >> other ongoing discussion on this. >> >>> >>> And it's sounding like for other scenarios you are going to resign >>> yourself to there not being a common UART so you will send the pre-console >>> (panic) message to multiple UARTs - something that should be avoided at >>> all costs... >> >> Of course - we cannot require the board to use a particular UART. The >> SOCs have various options and different people will make different >> decisions. Honestly, if we can't deal with UART selection in the >> device tree, we aren't going to solve the more difficult problems. > > But aren't we dealing in a case where the device tree is probably not > available anyway?
Yes. > > And we are talking about one board vendor taking a SoC and using UARTA > for the panic output and another board vendor deciding to use UARTB - But > surely these vendors will create a separate config file for their boards. Nope. There is only one u-boot.bin for all boards that use this SOC. > >>> I know we are dealing with a corner case abnormal situation here, but >>> something does not smell right... Maybe I'm not understanding something >>> obvious yet... >> >> I'm not sure. I suspect it could be easily explained with an hour at >> the whiteboard, but it's hard by email. >> >> The requirement is to output a message that the user can see, and we >> have a selection of UARTs which *might* be the console UART. For now >> we don't know exactly which one it is (see my SPL config comment >> though which might eventually solve this). So we send output to >> several of them. To protect against any danger, we permit the board >> file to select which are permitted. > > Again, we are going back to per-board configurations - Why can't this > selection be CONFIG_'d? Surely we could define a bitmap of available UARTs > in a SoC header (and reserve space for board specific UARTs) which can > then be used in the board config. > > I'm not really seeing an example of where two boards use exactly the same > configuration file and yet one has 'UARTx' plumbed and the other does not > > Sorry, I'm not trying to be difficult, just poking all the corners to see > what squishes ;) The key point is that they all have the same CONFIG and there is only one u-boot.bin. Once you understand that, the problem will become clearer. Regards, Simon > > Regards, > > Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
